Registration Dossier
Registration Dossier
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EC number: 954-921-6 | CAS number: -
Adsorption / desorption
Administrative data
Link to relevant study record(s)
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 24 Aug 2017 to 28 Jun 2018
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
- Version / remarks:
- 2000
- Deviations:
- yes
- Remarks:
- See Deviations from the guidelines in "Any other information on materials and methods incl. tables"
- Qualifier:
- according to guideline
- Guideline:
- other: EPA Guideline 835.1230
- Version / remarks:
- 2008
- Qualifier:
- according to guideline
- Guideline:
- other: JMAFF No. 12-Nousan-8147
- Version / remarks:
- 2000
- GLP compliance:
- yes (incl. QA statement)
- Type of method:
- batch equilibrium method
- Media:
- soil
- Radiolabelling:
- yes
- Test temperature:
- - 23.6 ± 0.3 °C (Ushiku and St. Triphon soil)
- 23.9 ± 0.2 °C (Hepler soil) - Analytical monitoring:
- yes
- Details on sampling:
- See 'Details on analytical methods'
- Matrix no.:
- #1
- Matrix type:
- sandy loam
- % Clay:
- 9
- % Silt:
- 22
- % Sand:
- 69
- % Org. carbon:
- 1.9
- pH:
- 4.8
- CEC:
- 13.6 meq/100 g soil d.w.
- Matrix no.:
- #2
- Matrix type:
- clay loam
- % Clay:
- 34
- % Silt:
- 40
- % Sand:
- 26
- % Org. carbon:
- 3.7
- pH:
- 7.4
- CEC:
- 17.5 meq/100 g soil d.w.
- Matrix no.:
- #3
- Matrix type:
- silt loam
- % Clay:
- 23
- % Silt:
- 56
- % Sand:
- 21
- % Org. carbon:
- 3
- pH:
- 5.4
- CEC:
- 14.8 meq/100 g soil d.w.
- Details on matrix:
- Sampling and handling of the soils was performed under consideration of ISO 10381-6. The plant cover was removed, if necessary, and the soil sampled from the upper soil layer. Details of the soils, including pesticide treatment history, along with key physico-chemical properties of the soils are provided in Table 1 in "Any other information on materials and methods incl. tables".
After arrive the test facility, the soils were stored at room temperature until use. Prior to use, the soils were air-dried at ambient temperature and passed through a 2 mm sieve. Disaggregation was performed with minimal force, so that the original texture of the soil changed as little as possible. The moisture content of each soil was determined by drying subsamples (approx. 5 g) in an infra-red moisture analyser at a temperature of approx. 120 °C until the sample weight was stable. The soil moisture content was calculated on dry weight basis. - Details on test conditions:
- The experiment was performed using all three soils, with a 48 hour adsorption step and a 24 hour desorption step. The adsorption only and adsorption/desorption experiments were carried out using separate tubes. A soil-to-solution ratio of 1:100 was used for all soils. The test substance was applied to soil/aqueous slurries to achieve nominal initial aqueous concentrations of 1.0, 0.5, 0.1, 0.05 and 0.01 µg/mL. A radioactivity mass balance was determined after the desorption phase (adsorption/desorption experiment) for each soil using the samples treated at the highest test concentration (nominal 1.0 µg/mL) and for Hepler soil at all test concentrations.
ADSORPTION ONLY EXPERIMENT
- Soil sample weight: 1 g (dry weight) per replicate
- Equilibration solution: 0.01 M CaCl2 (99 mL/replicate)
- Control conditions: No soil (test item in 0.01M CaCl2 only)
- Number of replicates: 2
- Test apparatus: Teflon tubes and seals
- Identity of solvent: Dosed in acetonitrile
- Volume of test solution used/treatment: 100 µL (0.01 M CaCl2 solution added to reach final volume. The amount of organic co-solvent in the slurries of treated samples was ≤ 0.1% v/v.)
- Application method: Syringe
- Evaporation of application solvent: No
- Nominal application rates: 1.0, 0.5, 0.1, 0.05, 0.01 µg/mL
- Actual application rates: 1.005, 0.506, 0.102, 0.051, 0.010 µg/mL (Ushiku and St. Triphon soil); 1.018, 0.508, 0.101, 0.051, 0.010 µg/mL (Hepler soil).
- Soil-Solution ratio: 1:100
- Indication of test material adsorbing to walls of test apparatus: Yes
- Continuous darkness (Yes/No): Yes
- Shaking method: Horizontal shaker
- Method of separation of supernatant: Centrifugation (Approx. 2800 rpm for 10 mins)
- Method of separating supernatants: Decanting
ADSORPTION/DESORPTION EXPERIMENT
- The parameters in experimental design are the same as in the adsorption only experiment
- Amount of test item present in the test system at the start of the desorption step: 0.718 – 0.812, 0.346 – 0.411, 0.076 – 0.086, 0.038 – 0.044, 0.008 – 0.009 µg/mL range.
- A mass balance was determined after the desorption phase using the samples treated at the highest concentration (for Ushiku soil and St. Triphon soil) or using the samples treated at all test concentrations (Hepler soil).
PREPRARATION OF TEST SOLUTION
- Ushiku and St. Triphon Soils: Fresh application solutions were prepared for the definitive test for each test item concentration. Application solution A, used for test concentration 1.0 µg/mL, was prepared by diluting an aliquot of the test item (lot no. RDR-XXVI-76; delivered by the Sponsor in acetonitrile) with acetonitrile to a final volume of 2.5 mL, followed by homogenization on a mechanical shaker. The radioactivity content in application solution A was 257’326’667 dpm/mL, corresponding to a concentration of 995.1 µg of 14C-labelled test substance/mL. The application solution B, used for test concentration 0.5 µg/mL, was prepared by combining an 800 µL aliquot of application solution A with 800 µL of acetonitrile. The radioactivity content of this application solution was 131’367’000 dpm/mL, corresponding to a concentration of 508.0 µg of 14C-labelled test substance/mL. The application solution C, used for test concentration 0.1 µg/mL, was prepared by combining a 200 µL aliquot of application solution A with 1800 µL of acetonitrile. The radioactivity content of this application solution was 26’619’400 dpm/mL, corresponding to a concentration of 102.9 µg of 14C-labelled test substance/mL. The application solution D, used for test concentration 0.05 µg/mL, was prepared by combining a 200 µL aliquot of application solution B with 1800 µL of acetonitrile. The radioactivity content of this application solution was 13’556’800 dpm/mL, corresponding to a concentration of 52.4 µg of 14C-labelled test substance/mL. The application solution E, used for test concentration 0.01 µg/mL, was prepared by combining a 200 µL aliquot of application solution C with 1800 µL of acetonitrile. The radioactivity content of this application solution was 2’649’860 dpm/mL, corresponding to a concentration of 10.2 µg of 14C-labelled test substance/mL.
- Hepler Soil: The application solutions for Hepler soil were prepared using an aliquot of the test item (lot no. NP-II-39; delivered by the Sponsor in acetonitrile). The corresponding application solutions were prepared similarly to those for Ushiku and St. Triphon soils, resulting in
radioactive concentrations of 287’360’000 dpm/mL (1014.7 µg 14C-labelled test substance/mL) for application solution A2, 144’589’600 dpm/mL (510.6 µg/mL) for application solution B2, 29’162’000 dpm/mL (103.0 µg/mL) for application solution C2, 14’546’040 dpm/mL (51.4 µg/mL) for application solution D2 and 2’948’200 dpm/mL (10.4 µg/mL) for application solution E2.
TREATMENT OF SLURRIES WITH 14C-LABELLED TEST SUBSTANCE
- Preparation of soil slurries prior to treatment: Prior to treatment with the test substance, soil samples were equilibrated at least overnight in Teflon tubes with aqueous CaCl2 (0.01 M) solution. Each tube contained 1 g (dry weight equivalent) of soil. A volume of 0.01 M CaCl2 solution corresponding to 99% of the final aqueous volume was added. The untreated soil slurries were incubated in the dark at 24 ± 1 °C (mean ± standard deviation) and continuously agitated on a horizontal shaker (approximately 200 revolutions per minute (r.p.m.)).
- After pre-equilibration of the soil with about 99% of the targeted volume of 0.01 M CaCl2 solution, aliquots of the corresponding application solutions were added to the surface of the supernatant. The amount of organic co-solvent in the slurries of treated samples was ≤ 0.1% v/v.Control samples containing the test item in 0.01 M CaCl2 solution (without soil) were subjected to precisely the same steps as the test samples in order to check the stability of the test item in CaCl2 solution and potential adhesion of the test item to the tube walls. The application scheme is summarised in the Table 2 in "Any other informationon materials and methods incl. tables". - Duration:
- 48 h
- Remarks:
- duration of adsorption step for all 3 types of soil and 5 tested concentrations
- Duration:
- 24 h
- Remarks:
- duration of desorption step for all 3 types of soil and 5 tested concentrations
- Computational methods:
- Calculations were performed with a commercially available computer program. The results presented in the tables are rounded to the last displayed digit. For further calculations, the exact data were used. Thus, manual calculations using rounded data may differ slightly from those using exact data.
The concentration of the test item in the aqueous phase (Ce) was calculated based on the results of the radio-assays. The concentration of test item adsorbed onto soil particles (Cs = x/m; x: amount of test item adsorbed, m: mass of dry soil) was obtained indirectly by calculating the difference between the applied amount of radioactivity and the total amount of radioactivity present in the aqueous phase and the rinse of the test tubes. HPLC and TLC analyses demonstrated stability of the test item in the supernatant as well as in the soil during the experiment, therefore no correction was required. - Key result
- Sample No.:
- #1
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 4 921 L/kg
- pH:
- 5.33
- Temp.:
- 23.6 °C
- Matrix:
- Sandy loam
- % Org. carbon:
- 1.9
- Key result
- Sample No.:
- #2
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 5 518 L/kg
- pH:
- 7.43
- Temp.:
- 23.6 °C
- Matrix:
- Clay loam
- % Org. carbon:
- 3.7
- Key result
- Sample No.:
- #3
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 7 260 L/kg
- pH:
- 6.02
- Temp.:
- 23.9 °C
- Matrix:
- Silt loam
- % Org. carbon:
- 3
- Sample No.:
- #1
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 10 255 L/kg
- Temp.:
- 23.6 °C
- pH:
- 5.33
- Matrix:
- Sandy loam
- % Org. carbon:
- 1.9
- Sample No.:
- #2
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 6 329 L/kg
- Temp.:
- 23.6 °C
- pH:
- 7.43
- Matrix:
- Clay loam
- % Org. carbon:
- 3.7
- Sample No.:
- #3
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 10 173 L/kg
- Temp.:
- 23.9 °C
- pH:
- 6.02
- Matrix:
- Silt loam
- % Org. carbon:
- 3
- Adsorption and desorption constants:
- See Table 8 in 'Any other information on results incl. tables'
- Recovery of test material:
- See Table 3 in 'Any other information on results incl. tables'
- Concentration of test substance at end of adsorption equilibration period:
- See Table 4 - 7 in 'Any other information on results incl. tables'
- Concentration of test substance at end of desorption equilibration period:
- See Table 4 - 7 in 'Any other information on results incl. tables'
- Remarks on result:
- other: See Table 3 in 'Any other information on results incl. tables'
- Remarks on result:
- other: See Table 3 in 'Any other information on results incl. tables'
- Transformation products:
- not specified
- Details on results (Batch equilibrium method):
- RADIOCHEMICAL PURITY
The purity of 14C-labelled test substance was determined to be ≥ 97.7% by HPLC analysis of application solution A and A2 both before and after treatment.
MASS BALANCE
The amount of radioactivity in the residual water after the adsorption step was accounted to the adsorption aqueous phase. The amount of radioactivity in desorption aqueous phase was therefore corrected for radioactivity originating from the residual water after the adsorption step. Similarly, the amount of radioactivity in the residual water after the desorption step was accounted to the desorption aqueous phase. The mass in the residual water after the desorption step only corresponded to ≤ 0.3% of applied radioactivity (data not shown). The mass was considered negligible and the soil-transfer solutions were therefore not corrected for radioactivity originating from the residual water after the desorption step, thereby resulting in a marginal overestimation of the total mass balance recoveries. The total mass balance ranged between 100.2% and 103.1% of applied radioactivity (AR) among all soils. The majority of the radioactivity was present in the soil extracts, with values ranging from 38.4% to 71.3% AR. The amount of radioactivity the aqueous phase ranged between 12.5% and 29.0% AR for the adsorption phase and between 9.5% and 19.0% AR for the desorption phase. The amount of radioactivity detected in the tube rinse ranged between 4.9% and 11.3% AR. Only minor amounts of radioactivity were detected in the soil-transfer solutions (up to a maximum of 3.9% AR). The amount of radioactivity irreversibly bound to the soil accounted for a maximum of 1.2% AR. The high mass balance recoveries showed that radioactivity adsorbed to the tube walls could be completely recovered. The combination of high mass balance recoveries, low amounts of unextracted residues and low amounts of radioactivity in the soil transfer solutions also demonstrated that the indirect approach to calculate the amount of test item adsorbed to soil by subtraction of the amount of radioactivity determined in the aqueous phase and the tube rinsing solution from the initially amount applied was valid. The total mass balance recovery of radioactivity from the adsorption aqueous phase and tube rinses of soilless control samples (48 hours of agitation without soil) treated at different test concentrations ranged from 99.9% AR to 102.6% AR. In the absence of soil, individual samples showed considerable variability regarding the adsorption of the test item to the tube walls (ranging from 22.8% - 92.3% AR). However, the total recoveries confirmed that radioactivity could be completely recovered again even if adsorbed to the tube walls at such high levels.
STABILITY OF THE RADIOLABELLED TEST SUBSTANCE DURING ISOTHERM TEST: Supernatants and soil extracts of selected samples were analysed by HPLC or TLC to check for stability of 14C-labelled the test substance. Supernatants and soil extracts of samples treated at the highest test concentration (nominal 1.0 µg/mL) were analysed across all soils and additionally at all other test concentrations for Hepler soil (with exception of the adsorption and desorption supernatants of the lowest test concentration (0.01 µg/mL) due to limited sensitivity of the analytical method). HPLC and/or TLC analysis of supernatants and soil extracts showed 14C-labelled the test substance to be ≥ 97.1%, demonstrating stability of 14C-labelled the test substance. Due to the fact that stability of 14C-labelled test substance was observed across all samples, test concentrations and soils, the results of chromatographic analysis were considered as a purity check and not used for correction of test item concentrations in all experiments. For calculation of partitions coefficients, stability of 14C-labelled test substance, e.g. 100% parent, was considered for all samples and experiments.
ISOTHERM
The distribution coefficients Kd and Koc were calculated based on the test item concentrations determined by LSC in the aqueous phase and in soil (determined by the indirect method) at all test concentrations and across all soils. Stability of 14C-labelled test substance was shown at all test concentrations and thus 100% parent was considered for calculation of partition coefficients for all samples. The Freundlich isotherms were generated after logarithmic transformation of the data. The Freundlich coefficients KF, KFOC and 1/n were derived from linear regression of the isotherms using all individual values (n=10 replicates per soil). The Koc values after 48 hours of adsorption (adsorption only experiment) ranged from 5’385 – 13346 mL/g, 6’241 – 13’344 mL/g and 9’069 – 19’787 mL/g for Ushiku, St. Triphon and Hepler soils, respectively, with average values of 9’059 mL/g, 9’605 mL/g and 13’512 mL/g for Ushiku, St. Triphon and Hepler soils, respectively. A good linear fit of the Freundlich adsorption isotherm was obtained for all soils with r2 values ≥ 0.9924. The Freundlich coefficients (KF) calculated for the adsorption step were 93.5 mL/g, 204.2 mL/g and 217.8 mL/g, with corresponding KFOC values of 4’921 mL/g, 5’518 mL/g and 7’260 mL/g for Ushiku, St. Triphon and Hepler soils, respectively. The corresponding 1/n values were 0.840, 0.860 and 0.851 for Ushiku, St. Triphon and Hepler soils, respectively, indicating a slight dependency of the adsorption process on the test item concentration. The r2 of the standard linear regression of the adsorption isotherms, the visual fit of the standard regression and the residual plots were acceptable. The lower and upper 95% confidence intervals for KF and 1/n were close to the fitted parameters of KF and 1/n. The Koc values after 48 hours of adsorption, followed by 24 hours of desorption ranged from 11’262 – 17’695 mL/g, 7’623 – 16’329 mL/g and 13’156 – 25’270 mL/g for Ushiku, St. Triphon and Hepler soils, respectively, with average values of 13’365 mL/g, 11’542 mL/g and 17’533 mL/g for Ushiku, St. Triphon and Hepler soils, respectively. A good linear fit of the Freundlich desorption isotherm was obtained for all soils with r2 values ≥ 0.9987. The Freundlich coefficients (KF) calculated for the desorption step were 194.8 mL/g, 234.2 mL/g and 305.2 mL/g, with corresponding KFOC values of 10’255 mL/g, 6’329 mL/g and 10’173 mL/g for Ushiku, St. Triphon and Hepler soils, respectively. The corresponding 1/n values were 0.933, 0.860 and 0.876 for Ushiku, St. Triphon and Hepler soils, respectively, indicating a slight dependency of the desorption process on the test item concentration. The r2 of the standard linear regression of the desorption isotherms, the visual fit of the standard regression and the residual plots were acceptable. The lower and upper 95% confidence intervals for KF and 1/n were close to the fitted parameters of KF and 1/n. The Freundlich coefficients KF and distribution coefficients Kd were higher after desorption compared to adsorption, indicating a partially irreversible adsorption process of the test item to soil. The apparent desorption coefficients expressed as a function of organic carbon Kdesoc were calculated at each test concentration for all soils under consideration of the residual water determined after the adsorption step, resulting in marginally higher Kdesoc values compared to Koc after desorption. The average values for the apparent desorption coefficients Kdesoc were 13’707 mL/g, 11’774 mL/g and 17’773 mL/g for Ushiku, St. Triphon and Hepler soils, respectively.
CHIRAL ANALYSIS
The ratio of the stereoisomers of the parent in both the application solution and the soil extracts was confirmed to be consistent with that reported in the Certificates of Analysis for the test items. Hence, it was confirmed that there was no change of stereochemistry during the incubation. - Statistics:
- Not reported
- Validity criteria fulfilled:
- yes
- Conclusions:
- The test substance adsorbed to all three soils with KFOC values ranging from 4921 to 7260 mL/g after adsorption and from 6329 to 10255 mL/g after desorption. The adsorption process was not fully reversible. Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KFOC), the test substance can be classified as “immobile” in Ushiku, St. Triphon and Hepler soils.
- Executive summary:
The adsorption/desorption characteristics of 14C-labelled test substance was studied in three soils: Ushiku Japanese Ash (Sandy loam; Japan), St. Triphon (Clay loam; Switzerland) and Hepler (Silt loam, USA) using a standard batch equilibrium method, in the dark at a temperature (mean ± standard deviation) of 23.6 ± 0.3 °C (Ushiku and St. Triphon soil) and 23.9 ± 0.2 °C (Hepler soil). This study was conducted according to guidelines: OECD TG 106, EPA 835.1230 and EU No. 283/2013 and it was compliant with GLP criteria.
Separate test vessels were set-up for the adsorption only and adsorption/desorption experiments. The radiolabelled test item was added to soil:aqueous slurries (resulting in a final nominal composition of 1 g of soil and 100 mL aqueous 0.01M CaCl2) to achieve five nominal rates of 1.0, 0.5, 0.1, 0.05 and 0.01 µg/mL. The adsorption time was 48 hours. The soil adsorption coefficients Kd and KOC, together with the Freundlich adsorption constants KF and KFOC, were determined for each soil in the adsorption only experiment. In the adsorption/desorption experiment, the adsorption period of 48 hours was followed by a single desorption phase of 24 hours. Similarly, the desorption coefficients Kd and KOC, together with the Freundlich desorption constants KF and KFOC were determined for each soil after the adsorption/desorption experiment.
Preliminary tests have shown that the test item exhibited strong adsorptive behaviour not only to the soil but also to the test tubes. Radioactivity adsorbed to the test tubes could be recovered by a tube rinsing step using acetonitrile/water acidified with formic acid to pH 3 (4/1; v/v). The rinsing step however required the removal of the soil phase from the test tube (soils were transferred to separate tubes using 0.01M CaCl2 as transfer solution) and therefore the set-up of separate test tubes for the adsorption only and adsorption/desorption experiments.
Mass balances (after adsorption/desorption) were determined at the highest test item concentration for each soil and at all concentrations for Hepler soil by radio assay of the adsorption supernatants, desorption supernatants, soil-transfer solutions, tube rinse, soil extracts and non-extractable soil residues. Stability of 14C-labelled test substance was verified by high performance liquid chromatography (HPLC) and/or thin layer chromatography (TLC) analyses of selected adsorption and desorption supernatants and soil extracts.
Good mass balance recoveries of radioactivity were achieved across all soils, ranging from 100.2 to 103.1% of applied the test substance. Stability of 14C-labelled test substance was shown in supernatants and soil extracts of the mass balance samples. Thus, 100% parent was considered for calculation of partition coefficients. The mean partition coefficient Kd values after adsorption ranged between 172.1 and 405.4 mL/g, with corresponding mean KOC values ranging between 9059 and 13512 mL/g. The mean Freundlich coefficients (KF) for adsorption were between 93.5 and 217.8 mL/g, with corresponding KFOC values for adsorption ranging between 4921 and 7260 mL/g. A good linear fit of the adsorption only isotherms was obtained for all soils with R2 values ≥ 0.9924.
The r2 of the standard linear regression of the adsorption isotherms, the visual fit of the standard regression and the residual plots were acceptable. The regression constant 1/n values ranged between 0.840 and 0.860, indicating a slight dependency of the adsorption process on the test item concentration. The lower and upper 95% confidence intervals for KF and 1/n were close to the fitted parameters of KF and 1/n. The mean partition coefficient Kd values after desorption, determined in the adsorption/desorption experiment, ranged between 253.9 and 526.0 mL/g. Corresponding mean KOC values after desorption ranged from 11542 to 17533 mL/g across all soils. The Freundlich coefficients (KF) for desorption ranged from 194.8 to 305.2 mL/g, with corresponding KFOC values for desorption ranging between 6329 and 10255 mL/g. A good linear fit of the desorption isotherms was obtained for all soils with r2 values ≥ 0.9987. The r2 of the standard linear regression of the desorption isotherms, the visual fit of the standard regression and the residual plots were acceptable. The regression constant 1/n values after desorption ranged from 0.860 to 0.933 across all soils, indicating a slight dependency of the desorption process on the test item concentration. The lower and upper 95% confidence intervals for KF and 1/n were close to the fitted parameters of KF and 1/n. The distribution coefficients Kd and Freundlich coefficients KF were generally higher for the desorption step (adsorption/desorption experiment) compared to the values obtained for the adsorption step (adsorption only experiment), indicating that the adsorption process of the test item to soil was not fully reversible.
The test substance adsorbed to all three soils with KFOC values ranging from 4921 to 7260 mL/g after adsorption and from 6329 to 10255 mL/g after desorption. The adsorption process was not fully reversible. Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KFOC), the test substance can be classified as “immobile” in Ushiku, St. Triphon and Hepler soils.
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 02 Jun 2017 to 23 Apr 2018
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
- Version / remarks:
- 2000
- Qualifier:
- according to guideline
- Guideline:
- other: EPA Guideline 835.1230
- Version / remarks:
- 2008
- Qualifier:
- according to guideline
- Guideline:
- other: Commission Regulation (EU) No 283/2013
- Version / remarks:
- 2013
- GLP compliance:
- yes (incl. QA statement)
- Type of method:
- batch equilibrium method
- Media:
- soil
- Radiolabelling:
- yes
- Test temperature:
- - 20.6 ± 0.1°C (adsorption only)
- 20.1 ± 0.1°C (adsorption/desorption) - Analytical monitoring:
- yes
- Details on sampling:
- A radioactivity mass balance was determined after the adsorption phase (for the adsorption only test) and after the desorption phase (for the adsorption/desorption test), for each soil using the samples treated at the highest test concentration (nominal 1.0 mg/L) and for Gleissolo soil at all test concentrations.
- Matrix no.:
- #1
- Matrix type:
- sandy clay
- % Clay:
- 37
- % Silt:
- 2
- % Sand:
- 61
- % Org. carbon:
- 2.7
- pH:
- 3.9
- CEC:
- 9.8 meq/100 g soil d.w.
- Matrix no.:
- #2
- Matrix type:
- sandy clay loam
- % Clay:
- 29
- % Silt:
- 22
- % Sand:
- 49
- % Org. carbon:
- 2.4
- pH:
- 5.4
- CEC:
- 26.5 meq/100 g soil d.w.
- Matrix no.:
- #3
- Matrix type:
- loamy sand
- % Clay:
- 11
- % Silt:
- 2
- % Sand:
- 87
- % Org. carbon:
- 10.2
- pH:
- 4.5
- CEC:
- 16 meq/100 g soil d.w.
- Matrix no.:
- #4
- Matrix type:
- sand
- % Clay:
- 0
- % Silt:
- 0
- % Sand:
- 100
- % Org. carbon:
- 0.78
- pH:
- 4.2
- CEC:
- 3.8 meq/100 g soil d.w.
- Details on matrix:
- COLLECTION AND STORAGE
- Geographic location: The soils were collected from different agricultural areas in Brazil.
- Collection procedures: Sampling and handling of the soils was performed under consideration of ISO 10381-6. The plant cover was removed, if necessary.
- Sampling depth (cm): the upper 20 cm soil layer
- Storage conditions: After arrival at the test facility, the soils were stored at room temperature until use.
- Soil preparation: Prior to use, the soils were air-dried at ambient temperature and passed through a 2 mm sieve. Disaggregation was performed with minimal force, so that the original texture of the soil changed as little as possible. The moisture content of each soil was determined by drying subsamples (approx. 5 g) in an infra-red moisture analyser. Samples were dried at a temperature of approx. 120 °C until the sample weight was stable. The soil moisture content was calculated on dry a weight basis.
Details of the soils, including pesticide treatment history, along with key physico-chemical properties of the soils are provided in the Table 1 in 'Any other information on materials and methods incl. tables' - Details on test conditions:
- The definitive experiment was performed using all four soils and separate tubes for the adsorption only and the adsorption/desorption experiment. The adsorption only experiment was conducted after a 24 hour adsorption period. The adsorption/desorption experiment consisted of a 24 hour adsorption period, followed by 24 hour desorption after removal and replacement of the aqueous phase. A soil-to-solution ratio of 1:100 was used for all soils and experiments, except Neossolo soil, which was conducted at a soil-to-solution ratio of 1:50 in both experiments. The test substance was applied to soil/aqueous slurries to achieve nominal aqueous concentrations of 1.0, 0.5, 0.1, 0.05 and 0.01 mg/L in both definitive experiments (adsorption only and adsorption/desorption).
EXPERIMENTAL DESIGN (Adsorption/Desorption experiment)
- Soil samples from adsorption experiment used : No
- Adsorption time (hours): 24
- Desorption time (hours): 24
- Number of desorption cycles: 1
- Soil condition: Air-dried soil, passed through 2 mm sieve
- Soil sample weight: 1 g (dry weight) per replicate (Latossolo, Argissolo and Gleissolo soils); 2 g (dry weight) per replicate (Neossolo soil)
- Equilibration solution: 0.01 M CaCl2 (90 mL/replicate)
- Control conditions: No soil (test item in 0.01M CaCl2 only)
- Number of replicates: 2
- Test apparatus: Teflon tubes and seals
- Identity of solvent: Dosed in acetonitrile
- Volume of test solution used/treatment: 100 µL; 0.01 M CaCl2 solution added to reach final volume. The amount of organic co-solvent in the slurries of treated samples was ≤ 0.1% v/v.
- Application method: Syringe
- Evaporation of application solvent: No
- Nominal application rates: 1.0, 0.5, 0.1, 0.05, 0.01 mg/L
- Actual application rates achieved: 0.990, 0.491, 0.099, 0.050, 0.010 mg/L
- Amount of test item present in the test system at the start of the desorption step: 0.670 – 0.820, 0.360 – 0.427, 0.072 – 0.086, 0.038 – 0.044
0.008 – 0.009 mg/L range.
- Soil-Solution ratio: 1:100 (Latossolo, Argissolo and Gleissolo soils); 1:50 (Neossolo soil)
- Indication of test material adsorbing to walls of test apparatus: Yes
- Equilibration Temperature: 20.1 ± 0.1 °C
- Equilibration Time: 24 hours adsorption + 24 hours desorption. The aqueous solution was removed after adsorption and replaced by fresh 0.01M CaCl2 solution prior to the desorption step.
- Continuous darkness (Yes/No): Yes
- Shaking method: Rotator
- Method of separation of supernatant: Centrifugation (Approx. 3900 / 3214 rpm for 10 mins)
- Method of separating supernatants: Decanting
EXPERIMENTAL DESIGN (Adsorption only experiment)
- Actual application rates achieved: 0.980, 0.482, 0.089, 0.048, 0.010 mg/L
- Equilibration Temperature: 20.6 ± 0.1 °C
- Equilibration Time: 24 hours adsorption
- Other parameters of experimental design are the same as in Adsorption/Desorption experiment
PREPARATION OF SOIL SLURRIES PRIOR TO TREATMENT
- Prior to treatment with the test substance, soil samples were equilibrated at least overnight in Teflon tubes with 0.01M aqueous CaCl2 solution. Each tube contained 1 g dry weight equivalent soil, except for Neossolo soil, which contained 2 g dry weight equivalent soil. A volume of 0.01 M CaCl2 solution corresponding to 90% of the final aqueous volume was added. The untreated soil slurries were incubated in the dark and under temperature-controlled conditions (20.6 ± 0.1 °C and 20.1 ± 0.1 °C for the adsorption only and adsorption/desorption experiment, respectively) and continuously agitated on a horizontal shaker (approximately 200 revolutions per minute (r.p.m.)). All tubes were uniquely labelled with the IES study number and any additional information necessary to ensure unambiguous identification.
PREPARATIOBN OF TREATMENT SOLUTIONS
- Preparation of stock solution: The complete amount of test item delivered by the Sponsor was transferred and rinsed into a separate flask and dissolved in acetonitrile. The solvent was evaporated to dryness using a gentle stream of nitrogen and re-dissolved in 5 mL of acetonitrile (= stock solution S2). This stock solution was kept at -20 °C until further use.
- Solutions used in the Definitive Adsorption only Test: Fresh application solutions were prepared for the definitive adsorption only test for each test item concentration from the stock solution. Application solution A, used for test concentration 1.0 mg/L, was prepared by diluting an aliquot of 1940 µL of the stock solution in acetonitrile to a final volume of 3200 µL. The radioactivity content in application solution A (determined by quintuplicate LSC measurements) was 256’404’000 dpm/mL, corresponding to a concentration of 991.5 µg of 14C-labelled test substance/mL. The application solution B, used for test concentration 0.5 mg/L, was prepared by combining a 1000 µL aliquot of application solution A with 1000 µL of acetonitrile. The radioactivity content of this application solution B was 126’658’667 dpm/mL, corresponding to a concentration of 489.8 µg of 14C-labelled test substance/mL. The application solution C, used for test concentration 0.1 mg/L was prepared by combining a 200 µL aliquot of application solution A with 1800 µL of acetonitrile. The radioactivity content of this application solution C was 26’668’667 dpm/mL, corresponding to a concentration of 103.1 µg of 14C-labelled test substance/mL. The application solution D, used for test concentration 0.05 mg/L, was prepared by combining a 200 µL aliquot of application solution B with 1800 µL of acetonitrile. The radioactivity content of this application solution D was 12’649’667 dpm/mL, corresponding to a concentration of 48.9 µg 14C-labelled test substance/mL. The application solution E, used for test concentration 0.01 mg/L, was prepared by combining a 200 µL aliquot of application solution C with 1800 µL of acetonitrile. The radioactivity content of this application solution E was 2’744’533 dpm/mL, corresponding to a concentration of 10.6 µg of 14C-labelled test substance/mL.
- Solutions used in Definitive Adsorption/Desorption Test: Stock solution (S3) was prepared by combining all remaining solutions from the previous experiments.The solvent was evaporated to dryness using a gentle stream of nitrogen and the test item subsequently re-dissolved in 3 mL of acetonitrile. Originating from this stock solution S3, fresh application solutions were prepared for the definitive adsorption/desorption test for each test item concentration. The application solution F, used for test concentration 1.0 mg/L, was prepared by diluting an aliquot of 2.26 mL of stock solution S3 in acetonitrile to final volume of 3.0 mL. The radioactivity content of this application solution F (determined by quintuplicate the test facility's measurements) was 261’086’000 dpm/mL, corresponding to a concentration of 1009.6 µg of 14C-labelled test substance/mL. The application solution G, used for test concentration 0.5 mg/L, was prepared by combining a 1000 µL aliquot of application solution F with 1000 µL of acetonitrile. The radioactivity content of this application solution G was 127’436’000 dpm/mL, corresponding to a concentration of 492.8 µg of 14C-labelled test substance/mL. The application solution H, used for test concentration 0.1 mg/L, was prepared by combining a 200 µL aliquot of application solution F with 1800 µL of acetonitrile. The radioactivity content of this application solution H was 25’653’600 dpm/mL, corresponding to a concentration of 99.2 µg of 14C-labelled test substance/mL. The application solution I, used for test concentration 0.05 mg/L, was prepared by combining a 200 µL aliquot of application solution G with 1800 µL of acetonitrile. The radioactivity content of this application solution I was 12’996’560 dpm/mL, corresponding to a concentration of 50.3 µg of 14C-labelled test substance/mL. The application solution K, used for test concentration 0.01 mg/L, was prepared by combining a 200 µL aliquot of application solution H with 1800 µL of acetonitrile. The radioactivity content of this application solution K was 2’584’940 dpm/mL, corresponding to a concentration of 10.0 µg of 14C-labelled test substance/mL.
TREATMENT OF SLURRIES WITH 14C-LABELLED TEST SUBSTANCE
- After pre-equilibration of the soil with about 90% of the targeted volume of 0.01 M CaCl2 solution, aliquots of the corresponding application solutions were added to the surface of the supernatant. The amount of organic co-solvent in the slurries of all treated samples was ≤0.1% v/v. The application scheme is summarised in the Table 2 in "Any other information on materials and methods incl. tables".
- Control samples containing the test item in 0.01 M CaCl2 solution (without soil) were subjected to precisely the same steps as the test samples in order to check the stability of the test item in CaCl2 solution and potential adhesion of the test item to the tube walls. - Duration:
- 24 h
- Temp.:
- 20 °C
- Remarks:
- duration of adsorption step for all 4 types of soil and 5 tested concentrations
- Duration:
- 24 h
- Temp.:
- 20 °C
- Remarks:
- duration of adsorption step for all 4 types of soil and 5 tested concentrations
- Computational methods:
- Calculations were performed with a commercially available computer program. The results presented in the tables are rounded to the last displayed digit. For further calculations, the exact data were used. Thus, manual calculations using rounded data may differ slightly from those using exact data.
The concentration of the test item in the aqueous phase (Ce) and the amount of test item adsorbed onto soil particles (x/m; x: amount of test item adsorbed, m: mass of dry soil) were calculated based on the results of the radio-assays. HPLC and TLC analyses demonstrated stability of the test item in the supernatant as well as in the soil during the experiments, therefore no correction required. - Key result
- Sample No.:
- #1
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 6 899 L/kg
- pH:
- 4.4
- Temp.:
- 20.6 °C
- Matrix:
- Sandy clay
- % Org. carbon:
- 2.7
- Key result
- Sample No.:
- #2
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 7 291 L/kg
- pH:
- 5.6
- Temp.:
- 20.6 °C
- Matrix:
- Sandy clay loam
- % Org. carbon:
- 2.4
- Key result
- Sample No.:
- #3
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 4 140 L/kg
- pH:
- 4.4
- Temp.:
- 20.6 °C
- Matrix:
- Loamy sand
- % Org. carbon:
- 10.2
- Key result
- Sample No.:
- #4
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 8 902 L/kg
- pH:
- 4.8
- Temp.:
- 20.6 °C
- Matrix:
- Sand
- % Org. carbon:
- 0.78
- Sample No.:
- #1
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 8 400 L/kg
- Temp.:
- 20.1 °C
- pH:
- 4.4
- Matrix:
- Sandy clay
- % Org. carbon:
- 2.7
- Sample No.:
- #2
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 7 626 L/kg
- Temp.:
- 20.1 °C
- pH:
- 5.6
- Matrix:
- Sandy clay loam
- % Org. carbon:
- 2.4
- Sample No.:
- #3
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 5 890 L/kg
- Temp.:
- 20.1 °C
- pH:
- 4.4
- Matrix:
- Loamy sand
- % Org. carbon:
- 10.2
- Sample No.:
- #4
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 18 987 L/kg
- Temp.:
- 20.1 °C
- pH:
- 4.8
- Matrix:
- Sand
- % Org. carbon:
- 0.78
- Adsorption and desorption constants:
- See Table 9 in 'Any other information on results incl. tables'
- Recovery of test material:
- See Table 3 in 'Any other information on results incl. tables'
- Concentration of test substance at end of adsorption equilibration period:
- See Table 4 - Table 8 in 'Any other information on results incl. tables'
- Concentration of test substance at end of desorption equilibration period:
- See Table 4 - Table 8 in 'Any other information on results incl. tables'
- Remarks on result:
- other: See Table 3 in 'Any other information on results incl. tables'
- Remarks on result:
- other: See Table 3 in 'Any other information on results incl. tables'
- Transformation products:
- not specified
- Details on results (Batch equilibrium method):
- RADIOCHEMICAL PURITY
The radiochemical purity of 14C-labelled test substance was determined to be ≥ 98.20% by HPLC analysis of application solution A, both before and after treatment. The multiple analysis of application solution A demonstrated stability of the test item in the application solution.
MASS BALANCE
The material balance of duplicate samples was determined after adsorption only and adsorption/desorption, respectively, for Gleissolo soil at all application rates and for all other soils at the highest application rate only.
For the adsorption only test, the mass balance was calculated as the sum of radioactivity in the adsorption supernatant, soil extract, soil-transfer solution, tube rinse and unextracted soil residues. The selected soil-to-solution ratio of 1:100 (Latossolo, Argissolo and Gleissolo soils) and 1:50 (Neossolo soil only) resulted in residual water volumes of less than 2 mL (on average, with one exception of 3 mL) (data not shown). The residual water was determined gravimetrically after the adsorption step, but not after transfer of the soil to separate tubes using the soil-transfer solution prior to soil extraction. The amount of radioactivity in soil transfer solutions was generally low (less than 3.9% AR). On the assumption that similar residual water volumes remained after the soil transfer and adsorption step, the contribution of the residual water after soil transfer to the mass balance was negligible (below 1% AR), based on values calculated using the highest quantified concentration in a soil-transfer solution and residual water after adsorption. Therefore, soil extracts after adsorption were not corrected for residual water of soil transfer solution.
The total mass balances after the adsorption only test ranged between 96.8% and 106.4% AR across all four soils, with three exceptions (73.7% AR (Latossolo replicate A at 1.0 mg/L), 117.7% (Gleissolo replicate A at 0.1 mg/L) and 80.6% AR (Gleissolo replicate A at 0.05 mg/L)). The corresponding replicate samples to the exceptional samples showed acceptable recoveries and thus the three exceptional samples did not impact the study. The majority of the radioactivity was found in the soil extracts, ranging from 39.9% AR to 86.6% AR across all soils and test concentrations, with one exception (20.7% AR (Latossolo replicate A at 1.0 mg/L)), which was confirmed by LSC re-analysis. Amounts of radioactivity determined in the aqueous phase ranged between 7.6% AR to 28.6% AR across all soils and test concentrations subjected to mass balance. A considerable amount of radioactivity was found in the tube rinsing solutions (ranging from 8.5 to 31.7% AR) among all soils subjected to mass balance. Variability of individual samples may be a result of the strong adsorptive behaviour of the test item e.g. to scratches in the tube walls. The soil transfer solutions accounted for a maximum of 3.9% AR and were a minor contribution to the total mass
balances. Unextracted residues accounted for a maximum of 1.2% AR across all soils subjected to mass balance.
For the adsorption/desorption test, the mass balance was calculated as the sum of radioactivity determined in the supernatant after adsorption and after desorption, respectively, the soil extract, the soil-transfer solution, the tube rinse after desorption and unextracted soil residues. The same soil-to-solution ratios were used as in the adsorption only experiment, resulting in similar residual water volumes (data not shown). Similar to the adsorption only experiment, the residual water was determined gravimetrically after the adsorption and desorption step, but not after transfer of the soil to separate tubes using the soil-transfer solution prior to soil extraction. The amount of radioactivity present in the soil transfer solutions were low (≤1.5% AR) and thus the contribution of the residual water after soil transfer to the mass balance was negligible. Therefore, soil extracts were not corrected for the residual water of soil transfer solution after the desorption step. However, the residual water determined after the adsorption phase was used for correction of the aqueous phase after desorption, representing the amount of test item desorbed from soil, which was used for calculating the apparent desorption coefficients.
The total mass balances after the adsorption/desorption test ranged between 98.8% and 101.4% AR across all four soils. The majority of the radioactivity was found in the soil extracts, ranging from 38.0% AR to 74.8% AR across all soils and test concentrations. Amounts of radioactivity determined in the aqueous phase ranged between 10.7% AR to 32.3% AR after the adsorption step and between 6.1% and 16.9% AR after the desorption step across all soils and test concentrations subjected to mass balance. Up to 17.1% AR was found in tube rinsing solutions among all soils and test concentrations. A minor contribution to the mass balance of the adsorption/desorption test originated from the soil transfer solutions (maximum 1.5% AR). Unextracted residues accounted for maximum 1.5% AR across all four soils subjected to mass balance.
Soil-less control samples demonstrated a significant and variable adsorption of 14C- labelled test substance to the test vessels in the absence of soil, ranging from 36.4% AR to 101.8% AR in the adsorption only test (duplicate samples per test concentration determined after 24 hours of shaking) and between 27.9% AR to 83.5% AR in the adsorption/desorption test (duplicate samples per test concentration determined after 48 hours of shaking). Variability may be due to the strong adsorptive behaviour of the test item and i.e. scratches in the test vessel wall. The total recoveries of the soil-less control samples, as determined by LSC of the aqueous solution and test vessel rinsing solution, were within an acceptable range (between 97.9% and 108.2% among both experiments), with two exceptions (120.7% and 119.0%, both at 0.1 mg/L during adsorption only).
Total recoveries in soil-less control and treated soil samples demonstrated that 14C- labelled test subtsnace adsorbed to the tube walls could be completely recovered by rinsing the Teflon test tubes using acetonitrile/water after removing the aqueous and soil phases. As a consequence it was decided to use the indirect approach for all other samples in the definitive tests and to calculate the amount of test item adsorbed to soil by subtraction of the amount of radioactivity determined in the tube rinsing solution and the aqueous phase from the initially amount applied.
STABILITY OF 14C-LABELLED TEST SUBSTANCE DURING THE ISOTHERM TEST
Duplicate samples (aqueous and extracts) at the highest test concentration (nominal 1.0 mg/L) were analysed across all soils and additionally at all other test concentrations for Gleissolo soil, with exception of the the aqueous phases of the lowest test concentrations (0.05 and 0.01 mg/L), due to limited sensitivity of the analytical method. Due to the fact that stability of 14C-labelled test substance was observed among all samples, test concentrations and soils, the results of chromatographic analysis were considered as a purity check and not used for correction of test item concentrations in all experiments. For calculation of partitions coefficients, stability of 14C-labelled test substance, e.g. 100% parent, was considered for all samples and experiments.
ISOTHERMS
The distribution coefficients Kd and Koc were calculated based on the test item concentrations determined by the test facility in the aqueous phase and in soil (determined by the indirect method) at all test concentrations and across all soils. Stability of 14C-labelled test substance was shown at all test concentrations and thus 100% parent was considered for calculation of partition coefficients for all samples.
The average Koc(ads) values after adsorption only were determined to be 11’473 mL/g, 12’095 mL/g, 7’490 mL/g and 15’472 mL/g for Latossolo, Argissolo, Gleissolo and Neossolo soils, respectively. The average Koc(des) values after desorption of the adsorption/desorption experiment were 14’959 mL/g (Latossolo), 15’907 mL/g (Argissolo), 9’947 mL/g (Gleissolo) and 25’241 mL/g (Neossolo) . The apparent desorption coefficients (Koc(des)app) were calculated at each test concentration for all soils under consideration of the residual water determined after the adsorption step, resulting in slightly higher Koc(des)app values compared to Koc(des). The average values for the apparent desorption coefficients (Koc(des)app) accounted for 15’201 mL/g, 16’179 mL/g, 9’108 mL/g and 20’294 mL/g for Latossolo, Argissolo, Gleissolo and Neossolo soils, respectively.
The test item concentrations of the aqueous phase and soil extract, determined in the adsorption only experiment, were used for generating the Freundlich isotherms after logarithmic transformation. A good linear fit of the adsorption isotherms was obtained for all soils with R2 values ≥ 0.9949. The Freundlich coefficients KF, KFoc and 1/n were derived from linear regression of the isotherms using all individual values (n=10 replicates per soil). The KF(ads) values were 186 mL/g, 175 mL/g, 422 mL/g and 69 mL/g with corresponding KFoc values of 6’899 mL/g, 7’291 mL/g, 4’140 mL/g and 8’902 mL/g for Latossolo, Argissolo, Gleissolo and Neossolo soils, respectively. The corresponding 1/n values were 0.873, 0.875, 0.874 and 0.857 for Latossolo, Argissolo, Gleissolo and Neossolo soils, respectively , indicating a slight dependency of the adsorption process on the test item concentration.
A good linear fit of the desorption isotherms was obtained for all soils with R2 values ≥ 0.9945. The Freundlich coefficients KF(des), KFoc(des) and 1/n were derived from linear regression of the desorption isotherms using all individual values (n=10 replicates per soil, except for soil Argissolo n=9, due to sample loss during preparation). The KF(des) values accounted for 227 mL/g, 183 mL/g, 601 mL/g and 148 mL/g with corresponding KFoc(des) values of 8’400 mL/g, 7’626 mL/g, 5’890 mL/g and 18’987 mL/g for Latossolo, Argissolo, Gleissolo and Neossolo soils, respectively. The corresponding 1/n values accounted for 0.868, 0.838, 0.892 and 0.932, indicating a slight dependency of the desorption process on the test item concentration.
The Freundlich coefficients KF and distribution coefficients Kd were generally higher after desorption in the adsorption/desorption experiment compared to adsorption only experiment, indicating that the adsorption process of the test item to soil was not entirely reversible.
KF(ads) values obtained for the different soils in the adsorption only experiment were plotted against various soil parameters (e.g. organic carbon, pH, cation exchange capacity, percentage of clay, silt and sand). A positive correlation between KF values and the organic carbon content was observed (R2 = 0.9746). All other soil parameters did not show any correlation against KF values.
CHIRAL ANALYSIS
The application solution A of the radiolabelled test item, used in the definitive adsorption only test, as well as aqueous solutions and acetonitrile/water soil extracts of each soil, originating from the highest test concentration (1.0 mg/L) after adsorption only,were analysed by chiral LC-MS to determine the isomer ratio of parent. The ratio of the stereoisomers of the parent in the application solution, the aqueous solutions and the soil extracts was confirmed to be consistent with that reported in the Certificate of Analysis for the test item. Hence, it was confirmed that there was no change of stereochemistry during the experiments. - Statistics:
- Not reported
- Validity criteria fulfilled:
- yes
- Conclusions:
- The test substance adsorbed to all four Brazilian soils with KOC values ranging from average 7’490 to 15’472 mL/g after adsorption only and between 9’947 and 25’241 mL/g after desorption in the adsorption/desorption experiment. The adsorption process was not fully reversible. The Freundlich coefficients KF ranged between 69 to 422 mL/g and 148 to 601 mL/g after adsorption only and after desorption in the adsorption/desorption experiment, respectively. A positive correlation between the Freundlich adsorption coefficient KF(ads) and the organic carbon content of the soils was observed (R2 = 0.9746). Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KOC), SYN547407 can be classified as “immobile” in all four investigated soils.
- Executive summary:
The adsorption/desorption characteristics of 14C-labelled test substance was studied in four Brazilian soils: Latossolo (sandy clay), Argissolo (sandy clay loam), Gleissolo (loamy sand) and Neossolo (sand) using a batch equilibrium method, in the dark under temperature-controlled conditions. The study was conducted according to guidelines: OECD TG 106, EPA 835.1230 and EU No. 283/2013 and it was compliant with GLP criteria.
The temperature during incubation was 20.6 ± 0.1°C (mean ± standard deviation of mean) and 20.1 ± 0.1°C (mean ± standard deviation of mean) in the definitive test after adsorption only and after adsorption/desorption, respectively. Soil-to-aqueous solution ratios of 1:100 (1 g soil and 100 mL CaCl2 solution) for Latossolo, Argissolo and Gleissolo soils and 1:50 (2 g soil and 100 mL CaCl2 solution) for Neossolo soil were used during the definitive tests. Separate test vessels were set-up for the adsorption only and adsorption/desorption experiments and in each of these experiments, the labelled test item was added to soil:aqueous slurries to achieve five nominal rates of 14C-labelled test substance at 1.0, 0.5, 0.1, 0.05 and 0.01 mg/L. The adsorption time was 24 hours in both definitive experiments and the desorption time in the adsorption/desorption experiment was 24 hours, following a previous adsorption period of 24 hours.Preliminary investigations have shown that the test item exhibited strong adsorptive behaviour to both the soils and the test vessels, independent on the test vessel material (polypropylene and Teflon were tested). Acceptable and reproducible recoveries, independent of the presence of soil or in soil-less control samples, were obtained using Teflon tubes and including a tube rinsing step using acetonitrile/water (1:1, v/v), after removal of the aqueous and soil phases from the test vessels, to determine the amount adsorbed to test vessel itself for each individual tube. Teflon tubes were used for all definitive experiments and the amount of test item adsorbed to the test vessel, as determined by the test facility of the tube rinsing solution, was considered for calculation of the amount adsorbed to soil for each individual tube. Before rinsing the test vessels with acetonitrile/water (1:1, v/v), the soils were transferred to separate tubes (after removal of the adsorption and/or desorption supernatants) by rinsing with 0.01M CaCl2 solution, and the amount of radioactivity in this rinsing transfer solution was quantified by the test facility.
Mass balances were determined for duplicate samples after adsorption only and adsorption/desorption at the highest test item concentration (1.0 mg/L) for each soil and at all test concentrations for Gleissolo soil by radioassay of the supernatants (after adsorption and desorption, respectively), the rinsing transfer solution, the test vessel rinsing solution, the soil extracts and the non-extractable soil residues. Stability of 14C-labelled test substance was verified by high-performance liquid chromatography (HPLC) and/or thin layer chromatography (TLC) analyses of the mass balance samples (aqueous solutions after adsorption only and after adsorption/desorption and in soil extracts after adsorption only and adsorption/desorption).
Acceptable total recoveries of radioactivity were achieved across all investigated soils ranging from 96.8% to 106.4% of applied radioactivity (AR), after adsorption only, with three exceptions (73.7% AR (Latossolo replicate A at 1.0 mg/L), 117.7% (Gleissolo replicate A at 0.1 mg/L) and 80.6% AR (Gleissolo replicate A at 0.05 mg/L)). Total recoveries of radioactivity obtained after adsorption/desorption ranged between 98.8% and 101.4% of initially applied radioactivity across all soils.
Stability of 14C-labelled test substance was shown in aqueous solutions and soil extracts after adsorption only and adsorption/desorption across all soils and test concentrations. Thus, 100% parent was considered for calculation of partition coefficients in all experiments. The calculated distribution coefficients Koc(ads) after adsorption only ranged between 7’490 mL/g and 15’472 mL/g (average values) among all soils and test concentrations. The Freundlich adsorption coefficients (KF) after adsorption only ranged between 69 mL/g and 422 mL/g (mean values) across all soils. A good linear fit of the adsorption only isotherms was obtained for all soils with R2 values ≥ 0.9949. The regression constant 1/n ranged between 0.857 and 0.875 after adsorption only across all soils, indicating a slight dependency of the adsorption process on the test item concentration. The calculated distribution coefficients Koc(des) after desorption, determined in the adsorption/desorption experiment, ranged between 9’947 mL/g and 25’241 mL/g (mean values) among all soils and test concentrations. The Freundlich desorption coefficients (KF(des)) after desorption ranged between 148 mL/g and 601 mL/g across all soils. A good linear fit of the desorption isotherms was obtained for all soils with R2 values ≥ 0.9945. The regression constant 1/n ranged between 0.838 and 0.932 after desorption across all soils, indicating a slight dependency of the desorption process on the test item concentration.
The Freundlich coefficients KF and distribution coefficients Kd were generally higher after the desorption step in the adsorption/desorption experiment compared to the values obtained in the adsorption only experiment, indicating that the adsorption process of the test item to soil was not entirely reversible. A positive correlation between the Freundlich adsorption coefficient KF(ads) and the organic carbon content of the soils was observed (R2 = 0.9746). Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KOC), isocycloseram can be classified as “immobile” (Koc > 5000 mL/g) in all four investigated soils.
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 31 Aug 2016 to 18 Oct 2017
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
- Version / remarks:
- 2000
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: EPA 835.1230
- Version / remarks:
- 2008
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- other: EU No 283/2013
- Version / remarks:
- 2013
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Type of method:
- batch equilibrium method
- Media:
- soil
- Radiolabelling:
- yes
- Test temperature:
- 20.6 ± 0.2 °C
- Analytical monitoring:
- yes
- Details on sampling:
- See 'Details on analytical methods'
- Matrix no.:
- #1
- Matrix type:
- loamy sand
- % Clay:
- 4
- % Silt:
- 10
- % Sand:
- 86
- % Org. carbon:
- 0.54
- pH:
- 5.2
- CEC:
- 4.4 meq/100 g soil d.w.
- Matrix no.:
- #2
- Matrix type:
- sandy clay loam
- % Clay:
- 24
- % Silt:
- 22
- % Sand:
- 54
- % Org. carbon:
- 1.8
- pH:
- 6.2
- CEC:
- 16.7 meq/100 g soil d.w.
- Matrix no.:
- #3
- Matrix type:
- loam
- % Clay:
- 23
- % Silt:
- 34
- % Sand:
- 43
- % Org. carbon:
- 0.72
- pH:
- 6.5
- CEC:
- 18.3 meq/100 g soil d.w.
- Matrix no.:
- #4
- Matrix type:
- loam
- % Clay:
- 24
- % Silt:
- 42
- % Sand:
- 34
- % Org. carbon:
- 2.2
- pH:
- 6.5
- CEC:
- 17.7 meq/100 g soil d.w.
- Matrix no.:
- #5
- Matrix type:
- sandy loam
- % Clay:
- 6
- % Silt:
- 24
- % Sand:
- 70
- % Org. carbon:
- 1.8
- pH:
- 7
- CEC:
- 12.7 meq/100 g soil d.w.
- Matrix no.:
- #6
- Matrix type:
- loam
- % Clay:
- 9
- % Silt:
- 49
- % Sand:
- 42
- % Org. carbon:
- 2
- pH:
- 7.2
- CEC:
- 8.6 meq/100 g soil d.w.
- Details on matrix:
- Details of the soil sampling locations, method of sampling and plot histories are provided in Table 1 in 'Any other information on materials and methods incl. tables'
COLLECTION AND STORAGE
- Geographic location: Six soils were collected from different agricultural areas.
- Collection procedures: Sampling and handling of the soils was performed under consideration of ISO 10381-6. The plant cover was removed, if needed.
- Sampling depth (cm): Soil sampled from the upper 20 cm soil layer.
- Storage conditions: The soils were stored in a closed container at ambient temperature in the dark at the test facility until use.
- Soil preparation: The soils, air-dried at ambient temperature, were passed through a 2 mm sieve. Disaggregation was performed with minimal force, so that the original texture of the soil changed as little as possible. The soils were homogenised and the moisture content determined by heating three soil aliquots of each soil in an infrared drier until there was no substantial change in weight. As the soils were air dry and contained maximum moisture content levels of 2.36g/100 g, no calculations were required to adjust the weighing of the soils throughout the study.
- Details on test conditions:
- Study design see Table 3 and Table 4 in 'Any other information on materials and methods incl. tabels'.
- Solvents and Reagents: All chemicals and reagents were purchased from commercial sources and were of analytical grade or comparable.
PREPARATION OF SOIL SLURRIES PRIOR TO TREATMENT
- Test vessel: 250 mL conical-bottomed polypropylene tubes
- Slurries of specific soil: aqueous solution ratio were prepared according to soil type. Ratios of 1:50 (Seven Springs and Capay soils) and 1:100 (18 Acres, Sarpy, East Anglia and Gartenacker soils) were used. All experiments involved an equilibration step, where soil samples (1 g or 2 g, depending on the soil) were equilibrated with 95% of the target volume (95 mL) of the aqueous phase (0.01 M CaCl2) by shaking for at least overnight at 20.6 ± 0.2 °C prior to application of the test item. The tubes were shaken in the dark at forces sufficient enough to keep the soil in homogeneous suspension. All experiments included controls and blanks and these were also performed at a constant temperature of 20.6 ± 0.2 °C.
PREPARATION OF TREATMENT SOLUTIONS
- Stock solution A: Radio-labelled Stock Solution A was prepared by dissolving the whole amount of the 14C-labeled test
item (lot no. RDR/XXV-30) in 10 mL of acetonitrile. The amount of radioactivity in the 10 mL stock solution was determined by LSC to be 5,494,522,222 dpm (91.58 MBq). Based on the provided specific activity of 4.76 MBq/mg, this corresponded to a test item chemical concentration of 1.92 mg/mL.
- Application solution PT1-7: Several application solutions were prepared for use in the preliminary tests by diluting Stock Solution A. These solutions were coded PT1 to PT7.
- Stock solution B: Radio-labelled Stock Solution B was prepared by dissolving the whole amount of the 14C test item (lot no. BRDR/XXVI-76) in acetonitrile to reach a final volume of 10 mL. The amount of radioactivity in the 10 mL stock solution was determined by LSC to be 2,127,060,000 dpm (35.45 MBq). Based on the provided specific activity of 4.31 MBq/mg, this corresponded to a test item chemical concentration of 0.82 mg/mL. Stock Solution B was used to prepare Application Solution B, which was used in the preliminary study to assess the extended stability and adsorption /desorption equilibrium test. A radio-isotopically diluted stock was prepared from Stock Solution B for use in the definitive adsorption/desorption test. For the radio-isotopic dilution, a non-radiolabelled stock solution was prepared by dissolving 2.65 mg of the non-radiolabelled test item (lot no. MS 1521/2, 98.4% purity) in 2 mL acetonitrile, giving a chemical concentration of 1.28 mg/mL.
- Application solution B: Application Solution B was prepared by diluting a 1.57 mL aliquot of Stock Solution B in a total volume of 30 mL acetonitrile which contained 331,821,360 dpm (5.53 MBq). Based on the provided specific activity of 4.31 MBq/mg, this corresponded to a test item chemical concentration of 0.04 mg/mL.
- Application solutions C and D (radio-isotopic dilution): For the definitive test; two radio-diluted application solutions were prepared; Application solution C which was used for the three highest test concentrations and Application solution D which was used for the two lowest test item concentrations. Application solution C was prepared by combining a 3 mL aliquot of the radiolabelled test item Stock Solution B, containing a total chemical amount of 2.47 mg test item, at a chemical concentration of 0.82 mg/mL with a 2 mL aliquot of the non-radiolabelled test item stock solution (Batch AMS 152/2, 98.4% pure), containing a total chemical amount of 2.56 mg test item, at a chemical concentration of 1.28 mg/mL. In a volumetric flask, the mixture was made up to an exact volume of 5 mL using acetonitrile and mixed by vortex. Thus, the total combined chemical quantity oF 14C-labelled test substance and 12C-labelled test substance in the 5 mL of radio-diluted application solution was 5.03 mg (2.47+2.56 mg). The homogeneity and the concentration of [14C]-labelled test substance in the radio-diluted Application solution C was assessed by LSC; triplicate dilutions were prepared, each in a volumetric flask (5 mL), where 50 µL of Application solution C was diluted with acetonitrile to 5 mL. Aliquots (100 µL) of each dilution were measured in triplicate by LSC and the solution found to be homogeneous. Application solution C was subsequently found to have an activity of 150,499,100 dpm/mL (2.51 MBq/mL), corresponding to 5.03 mg of [12C]+[14C] labelled test substance. Using a newly calculated specific activity of 2.49 MBq/mg, the chemical concentration of test item in Application Solution C was calculated to be 1.01 mg/mL. Application Solution D was prepared by diluting a 0.25 mL aliquot of Application Solution C in 5 mL acetonitrile and the homogeneity and concentration of the radiolabelled test item was assessed by LSC. Dilutions for LSC determination were prepared in triplicate. For each of the three volumetric flasks, 50 µL of Application Solution D was diluted with acetonitrile to give a final volume of 5 mL. Aliquots (100 µL) of each dilution were measured in triplicate by LSC and the solution found to be homogeneous. Application solution D was subsequently found to have an activity of 7,634,000 dpm/mL (0.13 MBq/mL). Using the specific activity of 2.49 MBq/mg this corresponded to a chemical concentration of 0.051 mg/mL. The identity, radiochemical purity and stability of the radiolabelled test item in the diluted application solutions used in both adsorption and desorption parts of the advanced test was assessed by HPLC before and after application.
TREATMENT OF SLURRIES WITH 14C-LABELLED THE TEST SUBSTANCE
For all experiments, after overnight equilibration with 90% of the targeted volume of the aqueous phase (0.01 M CaCl2), aliquots of the corresponding application solutions were added to the surface of the supernatant by means of an Eppendorf pipette, before the volume in the tube was made up to 100 mL with 0.01 M CaCl2. Control samples containing the test item in 0.01 M CaCl2 solution (without soil) were also run for all experiments and subjected to precisely the same steps as the test samples in order to monitor the stability of the test item in the CaCl2 solution and potential adhesion of the test item to the tube walls. The application procedure for the control samples was identical to the test samples summarised in the table above using a total volume equal to those in the corresponding tests. All experiments additionally included blanks (containing soil and 0.01 M CaCl2, but no test item) in order to monitor for any back ground interference contamination.
ADSORPTION AND DESORPTION EXPERIMENTS
- Adsorption only and Adsorption/Desorption experiments (adsorption step): Due to adherence to the vessel wall, the decision was taken to use the “direct method”. Two tubes (duplicate Polypropylene tubes) were shaken on an orbital shaker (at approximately 200 rpm) in the dark in a temperature-controlled room (20.6 ± 0.2 °C, mean ± standard deviation of mean) for 24 hours. The adsorption time of 24 hours was determined during the preliminary tests.
- Adsorption/Desorption experiments (desorption step): After the adsorption phase, the two tubes (duplicates per soil, per test concentration) continued on to the desorption phase. After decanting the adsorption solution from each of the incubated soil samples the same volume of fresh 0.01 M CaCl2 as that decanted, was added to the soil. Thereafter, the mixtures were shaken to disperse the soil, and placed again on a horizontal shaker in the dark in a temperature-controlled room (20.6 ± 0.2 °C, mean ± standard deviation of mean) for 24 hours. - Duration:
- 24 h
- Temp.:
- 20 °C
- Remarks:
- duration of adsorption step for all 6 types of soil and 5 tested concentrations
- Duration:
- 24 h
- Temp.:
- 20 °C
- Remarks:
- duration of desorption step for all 6 types of soil and 5 tested concentrations
- Computational methods:
- Calculations were performed with a commercially available computer program. The results presented in the tables are rounded to the last displayed digit. Appropriate calculations were conducted and reported according to the EFSA evaluator checklist tool. The regression function of the tool through excel was used to determine the necessary values. Thus, manual calculations using rounded data may differ slightly from those using exact data. The concentration of the test item in the aqueous phase (Ce) and the amount of test item adsorbed onto soil particles (x/m; x: amount of test item adsorbed, m: mass of dry soil) were calculated based on the results of the radio-assays (LSC). The amount of test item adsorbed onto soil particles (x/m) was obtained directly (using the direct extraction method) for every tube in the adsorption and desorption tests.
- Key result
- Sample No.:
- #1
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 7 795 L/kg
- pH:
- 5.2
- Temp.:
- 20 °C
- Matrix:
- Loamy sand
- % Org. carbon:
- 0.54
- Key result
- Sample No.:
- #2
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 12 788 L/kg
- pH:
- 6.2
- Temp.:
- 20 °C
- Matrix:
- Sandy clay loam
- % Org. carbon:
- 1.8
- Key result
- Sample No.:
- #3
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 9 307 L/kg
- pH:
- 6.5
- Temp.:
- 20 °C
- Matrix:
- Loam
- % Org. carbon:
- 0.72
- Key result
- Sample No.:
- #4
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 5 451 L/kg
- pH:
- 6.5
- Temp.:
- 20 °C
- Matrix:
- Loam
- % Org. carbon:
- 2.2
- Key result
- Sample No.:
- #5
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 7 383 L/kg
- pH:
- 7
- Temp.:
- 20 °C
- Matrix:
- Sandy loam
- % Org. carbon:
- 1.8
- Key result
- Sample No.:
- #6
- Type:
- Koc
- Remarks:
- Freundlich Coefficients
- Value:
- 6 600 L/kg
- pH:
- 7.2
- Temp.:
- 20 °C
- Matrix:
- Loam
- % Org. carbon:
- 2
- Sample No.:
- #1
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 11 534 L/kg
- Temp.:
- 20 °C
- pH:
- 5.2
- Matrix:
- Loamy sand
- % Org. carbon:
- 0.54
- Sample No.:
- #2
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 14 491 L/kg
- Temp.:
- 20 °C
- pH:
- 6.2
- Matrix:
- Sandy clay loam
- % Org. carbon:
- 1.8
- Sample No.:
- #3
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 21 565 L/kg
- Temp.:
- 20 °C
- pH:
- 6.5
- Matrix:
- Loam
- % Org. carbon:
- 0.72
- Sample No.:
- #4
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 7 873 L/kg
- Temp.:
- 20 °C
- pH:
- 6.5
- Matrix:
- Loam
- % Org. carbon:
- 2.2
- Sample No.:
- #5
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 9 605 L/kg
- Temp.:
- 20 °C
- pH:
- 7
- Matrix:
- Sandy loam
- % Org. carbon:
- 1.8
- Sample No.:
- #6
- Phase system:
- solids-water in soil
- Type:
- other: Koc - Desorption Freundlich Coefficients
- Value:
- 9 883 L/kg
- Temp.:
- 20 °C
- pH:
- 7.2
- Matrix:
- Loam
- % Org. carbon:
- 2
- Adsorption and desorption constants:
- The following constants were determined for the different soils:
Seven Springs: Kf = 42, Kd = 79 (adsorption); Kf = 62, Kd = 84 (desorption)
18 Acres: Kf = 230, Kd= 345 (ads); Kf = 261, Kd = 446 (des)
Capay: Kf = 67, Kd = 102 (ads); Kf = 155, Kd = 121 (des)
Sarpy: Kf = 120, Kd = 196 (ads); Kf = 173, Kd = 222 (des)
East Anglia: Kf = 133, Kd = 193 (ads); Kf = 173, Kd = 245 (des)
Gartenacker: Kf = 132, Kd = 200 (ads); Kf = 198, Kd = 233 (des) - Recovery of test material:
- The following recoveries were found:
Seven Springs: 97.2 - 101.3% for adsorption test; 97.7 - 103.2% adsorption/desorption test
18 Acres: 94.5 - 100.8% (ads); 96.6 - 99.9% (ads/des)
Capay: 97.3 - 100.5% (ads); 95.3 - 103.4% (ads/des)
Sarpy: 96.6 - 101.7% (ads); 96.3 -103.4% (ads/des)
East Anglia: 97.9 - 101.4% (ads); 98.2 - 105.1% (ads/des)
Gartenacker: 98.7 - 102.1% (ads); 99 - 102.2% (ads/des) - Concentration of test substance at end of adsorption equilibration period:
- See Table 7 - 12 in 'Any other information on results incl. tables'.
- Concentration of test substance at end of desorption equilibration period:
- See Table 7 - 12 in 'Any other information on results incl. tables'.
- Remarks on result:
- other: See Tabel 5 in 'Any other information results incl. tables'
- Remarks on result:
- other: See Table 6 in 'Any other information on results incl. tabels'.
- Transformation products:
- not specified
- Details on results (Batch equilibrium method):
- PRELIMINARY TEST
- Solubility: Difficulties were encountered in directly assessing whether the 14C-labelled test item was soluble at the concentrations used within the study as the test item has the propensity to bind/adhere to the test vessel walls. However, numerous preliminary tests using different types of vessels (HDPE, Teflon, glass and PP) and pre-treatments (silanising with Aquasil), clearly demonstrated a trending between test item concentration and the percent recovered in aqueous supernatants in soil-less control samples. Significantly lower recoveries in the aqueous phase were measured at lower application rates, which is indicative of adsorption to the vessel walls. Had the compound not been soluble at the highest dose concentration of 1 µg/mL, lower recoveries would have been expected at the higher test concentrations due to precipitation of the compound, which was not the case. The nominal highest dosing concentration in this study was 1 µg/mL, which was lower than the definitive solubility in water of 1.2 µg/mL for the 14C-labelled test item. Under the actual test conditions used, binding to the vessel walls would remove some of the test item available for partitioning, so the “actual” dosing concentration available for partitioning in the test would be lower than the nominal value stated.
- Ratio of soil to aqueous phase: Total recoveries (sum of supernatant, vessel wall rinse and soil extracts) were above 90% in all samples. As this was acceptable for the purposes of the preliminary test, no combustions were performed. At a soil to aqueous phase ratio of 1:50 w/v, mean values of 46.8 to 50.9% of applied radioactivity were adsorbed to Seven Springs and Capay soils. At a ratio of 1:100 w/v, mean values of 57.5% to 69.4% of applied radioactivity were adsorbed to 18 Acres, Sarpy, East Anglia and Gartenacker soils. As these values were all >20%, the soil to aqueous phase ratios were considered appropriate for the remaining tests in this study. The mean values of applied activity adhered to the vessel wall ranged from 6.4 to 13.7% which was deemed to be an acceptable level.
- Time to adsorption equilibrium: An adsorption equilibrium time of 24 hours was selected for use in the definitive test.
- Time to desorption equilibrium: A desorption equilibrium time of 24 hours was selected for use in the definitive test.
- Stability during equilibrium time: The 14C-labelled test substance was shown to be stable in the adsorption and desorption supernatants after a 72 hour equilibration periods and in their corresponding soil extract samples. Test item instability was not observed.
MAIN TEST: PERFORMANCE
- An overview of the results is provided in Table 7 - Table 13 in 'Any other information on results incl. tables'.
- Radiochemical purity: In order to determine the purity and stability of the 14C-labelled test substance during the application procedure, all application solutions were analysed by HPLC prior to and after treatment. The radiochemical purity of the application solutions determined by HPLC ranged from 98.93 and 98.99%, with an overall mean of 98.95%, demonstrating the stability of the test item in the application solutions.
- Treatment rate: The test concentrations were determined by LSC of acetonitrile/water solutions containing the actual application volume (performed in parallel to the adsorption and desorption test sample application, accounting for the slight variation in concentration on the different days. Actual values were close to the nominal concentrations. These values were used as 100% values for all data evaluation.
- Mass balance: Mass balance confirmed that quantitative recovery was achieved in all parts of the definitive test and that the intended application rate was always achieved.
- Stability of the 14C-labelled test substance: Stability of the 14C-labelled test substance under the experimental conditions was categorically demonstrated in the extensive tests carried out in the preliminary phase. Example HPLC chromatograms of the adsorption aqueous supernatant, from two representative soils after 72 h equilibration and the soil extracts, from all six soils after a total of 96 h equilibration, showed radioactivity was present as 100% unchanged parent in every analysis. Additionally, no degradation of the 14C-labelled test substance was observed in any of the soil free control samples (0.01 M CaCl2 only) from the the definitive phase or from the test-tube rinses of the soil free controls.
- Adsorption isotherms: Concentrations and % distribution of the 14C-labelled test substance was determined in the aqueous phases and in the soil, after 24 hours of adsorption. Partition adsorption coefficients (mean Kd) ranged from 79 mL/g to 345 mL/g, with corresponding mean KOC(ads) values ranged from 8,889 mL/g to 19,169 mL/g. Calculated mean Freundlich coefficients (KF) ranged from 42 mL/g to 230 mL/g, while the 1/n values ranged from 0.824 to 0.897. When corrected for the organic carbon content of the soils, the resultant mean KFOC(ads) values ranged from 5,451 mL/g to 12,788 mL/g. Calculated r2 values ≥ 0.988, indicate a good fit.
- Desorption isotherm: Desorption partition coefficients (mean Kd) ranged from 84 mL/g to 446 mL/g with associated mean KOC(des) values ranged from 10,113 mL/g to 24,763 mL/g. Calculated mean Freundlich desorption coefficients (KF(des)) ranged from 62 mL/g to 261 mL/g, while the 1/n values ranged from 0.878 to 1.069. Mean KFOC(des) values ranged from 7,873 mL/g to 21,565 mL/g. A good linear fit of the desorption isotherms was obtained with r2 values ≥ 0.985. Higher values were obtained for the Freundlich coefficients, KF, after desorption compared to adsorption. For all soils the organic carbon normalised Freundlich desorption coefficients (KFOC(des)c) were all higher when compared to adsorption (KFOC(ads)) indicating a partially irreversible adsorption process of the test item to soil, which varied from soil to soil.
- Chiral Analysis: Soil extraction samples for the highest concentration, i.e. 1.0 µg/mL after 24 hours of adsorption in the definitive test for all soils were analysed by chiral HPLC. The ratio of the stereoisomers of the test substance in the soil extracts was confirmed and showed no significant deviation from the isomer ratios determined in the test item. - Statistics:
- not reported
- Validity criteria fulfilled:
- yes
- Conclusions:
- The 14C-labelled test item was strongly adsorbed to all six soils tested (Seven Springs, loamy sand; 18 Acres, sandy clay loam; Capay, loam; Sarpy, loam; East Anglia, sandy loam; and Gartenacker, loam). Freundlich adsorption coefficients (KF) were in the range 42 mL/g to 230 mL/g and when corrected for organic carbon (KFOC) were in the range of 5,451 mL/g to 12,788 mL/g. Adsorption was not fully reversible, higher values were obtained for the Freundlich coefficients KF after desorption compared to adsorption. Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KFOC), 14C-labelled test substance can be classified as being immobile in all six soils.
- Executive summary:
The adsorption/desorption characteristics of the 14 C-labelled test substance was studied in six different soils: Seven Springs (loamy sand; USA), 18 Acres (sandy clay loam; UK), Capay (loam; USA), Sarpy (loam; USA), East Anglia (sandy loam; UK) and Gartenacker (loam; Switzerland), using a standard batch equilibrium method, in the dark at 20°C, using the “direct method” for quantification. This study was conducted according to guidelines: OECD TG 106 and EPA 835.1230 and it was in compliance with GLP criteria.
The temperature during incubation was 20.6 ± 0.2°C (mean ± standard deviation of mean) in the definitive adsorption and desorption tests. Soil-to-aqueous solution ratios of 1:100 (1 g soil and 100 mL CaCl2 solution) for 18 Acres, Sarpy, East Anglia and Gartenacker soils and 1:50 (2 g soil and 100 mL CaCl2 solution) for Seven Springs and Capay soils were used during the definitive tests. The test item was added to soil : aqueous slurries to achieve five nominal application rates of 1.0, 0.5, 0.1, 0.05 and 0.01 mg/L for the adsorption and desorption tests. The “direct method” was followed for all samples, since some binding to the test vessels was observed during preliminary tests.
For the direct method, applied first to the adsorption test; one duplicate set (Polypropylene tubes) were shaken for 24 hours after which time the aqueous phase was separated, volume recorded and radioactive content determined by LSC. Each resulting (weighed) soil pellet was frozen with dry ice before transferred as an intact frozen unit (with 0.01 M CaCl2 rinsing) into a new tube. The original, empty tube was then rinsed (20 mL, acetonitrile/water, 8:2; v/v, pH 3) and LSC performed on this “tube rinse” to determine the radioactive content which was unavailable for the partitioning test. Each soil pellet was then extracted (twice with 20 mL acetonitrile/water, 8:2, v/v, pH 3, 30 min, horizontal shaker) before centrifuging, to separate the soil from the extract. The total extract volume was recorded and radioactive content determined by LSC. For the desorption test a fresh, complete set-up of duplicate tubes was prepared in the same way as for the adsorption only test. The new adsorption samples were run and after 24 hour adsorption period the aqueous supernatant phase was removed and replaced with an equivalent volume of 0.01 M CaCl2. This initiated a 24 hour desorption test, after which rinsing, transfer, soil extraction and quantitation was done using the above described “direct method” in an identical way. Recovery of the applied radioactivity (mass balances) was determined for selected samples for the adsorption and desorption steps.
Soil adsorption coefficients (Kd and KOC) and Freundlich adsorption constants (KF and KFOC) were determined for each soil. Test item concentration was determined by radioassay of application controls prepared in parallel to test samples. Direct radioassays were determined for all the adsorption supernatants, desorption supernatants (during adsorption and desorption tests), rinsing solution of test vessel, soil extracts and where necessary, by combustion of non-extractable soil residues. Stability of the 14C-labelled test substance was verified by HPLC of selected adsorption and desorption supernatants and soil extracts. The isomeric ratio of the 14C-labelled test substance was also verified in selected samples.
Quantitative recovery of radioactivity (mass balances) after adsorption was achieved in all soils, with mean values ranging from 99.0 to 101.1% of applied radioactivity. The calculated partition coefficient KOC(ads) after 24 hours adsorption ranged from mean values of 8,889 mL/g (Sarpy) to 19,169 mL/g (18 Acres). Freundlich adsorption coefficients (KF) after adsorption ranged from 42 mL/g (Seven Springs) to 230 mL/g (18 Acres). Associated KFOC values ranged from 5,451 mL/g (Sarpy) to 12,788 mL/g (18 Acres). A good linear fit of the adsorption isotherms was obtained for all soils with r2 values ≥ 0.988. The regression constant 1/n values ranged from 0.824 (Seven Springs) to 0.897 (18 Acres) after adsorption, indicating some dependency of the adsorption process on the test item concentration.
Mass balances were also quantitative after desorption, with mean recoveries ranging from 98.5% to 101.6% of applied radioactivity for all test soils. The calculated partition coefficient KOC(des) after an additional 24 hours desorption ranged from mean values of 10,113 mL/g (Sarpy) to 24,763 mL/g (18 Acres). Associated KFOC(des) values ranged from 7,873 mL/g (Sarpy) to 21,565 mL/g (Capay). An acceptable linear fit of all the desorption isotherms was obtained, with r2 values > 0.985. The regression constant 1/n ranged from 0.878 (18 Acres) to 1.069 (Capay) after desorption, indicating a slight concentration dependency of the desorption process. Generally higher values were obtained for the Freundlich coefficients KF and distribution coefficient Kd after desorption compared to adsorption, indicating a partially irreversible adsorption process of the test item to soil.
HPLC analysis, conducted on the adsorption supernatants, tube rinses and soil extracts after a 24 hour adsorption then 24 hour desorption period, on all six soils and soil-free controls showed the test item to be stable. Since the test item is a chemical substance with asymmetric carbon atoms, the levels of stereoisomers were determined in selected soil extracts (for the highest concentration, for soils following 24h adsorption, in duplicate) by chiral HPLC analysis and the ratio showed no significant deviation from the isomer ratios determined in the test item.
Using the McCall Classification scale to assess a chemical’s potential mobility in soil (based on its KOC), the 14C-labelled test substance can be classified as “immobile” (KOC > 5,000 mL/g) in all six investigated soils.
Referenceopen allclose all
Table 3. Mass Balance
a) Adsorption/desorption test:
Adsorption / Desorption test |
|||||||||
Soil |
Nominal concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Aqueous phase after adsorption (%) |
Aqueous phase after desorption* (%) |
Soil transfer solution (%) |
Tube rinse (%) |
Soil extract (%) |
Unextracted residues (%) |
Total Recovery (%) |
Ushiku Japanese Ash |
1.0 |
1.005 |
28.6 |
17.6 |
3.9 |
11.3 |
38.4 |
0.4 |
100.2 |
29.0 |
19.0 |
3.3 |
10.6 |
39.4 |
0.4 |
101.6 |
|||
St. Triphon |
1.0 |
1.005 |
26.2 |
16.5 |
1.0 |
9.7 |
47.6 |
0.9 |
101.9 |
26.8 |
15.6 |
1.4 |
10.2 |
47.2 |
1.0 |
102.2 |
|||
Hepler |
1.0 |
1.018 |
20.3 |
13.8 |
1.4 |
7.5 |
57.2 |
1.0 |
101.3 |
20.9 |
14.1 |
1.4 |
8.9 |
55.0 |
1.0 |
101.3 |
|||
0.5 |
0.508 |
20.2 |
14.2 |
1.3 |
5.9 |
59.6 |
1.0 |
102.2 |
|
19.3 |
14.1 |
1.5 |
7.0 |
59.2 |
1.1 |
102.2 |
|||
0.1 |
0.101 |
15.9 |
12.2 |
1.2 |
8.4 |
64.3 |
1.1 |
103.1 |
|
15.5 |
12.7 |
1.6 |
7.8 |
64.0 |
1.1 |
102.6 |
|||
0.05 |
0.051 |
15.5 |
11.9 |
1.1 |
5.6 |
67.4 |
1.1 |
102.7 |
|
14.2 |
11.0 |
1.1 |
7.2 |
67.8 |
1.1 |
102.4 |
|||
0.01 |
0.010 |
12.5 |
9.7 |
1.7 |
8.1 |
68.5 |
1.2 |
101.6 |
|
12.5 |
9.5 |
1.2 |
4.9 |
71.3 |
1.2 |
100.5 |
|||
* Corrected for residual water after adsorption.
b) Distribution of radioactivity in the adsorption only test (indirect method used)
Adsorption only test |
||||||
Soil |
Nominal concentration (µg/mL) |
Achieved concentration (µg/mL) |
Aqueous phase after adsorption (%) |
Tube rinse (%) |
Adsorbed to soil* (%) |
Total Recovery (%) |
Ushiku Japanese Ash |
1.0 |
1.005 |
37.8 |
23.6 |
38.6 |
** |
36.5 |
26.0 |
37.4 |
** |
|||
0.5 |
0.506 |
31.9 |
24.1 |
44.0 |
** |
|
31.2 |
31.4 |
37.4 |
** |
|||
0.1 |
0.102 |
20.6 |
42.4 |
37.0 |
** |
|
21.5 |
37.9 |
40.5 |
** |
|||
0.05 |
0.051 |
20.5 |
35.2 |
44.3 |
** |
|
18.8 |
43.1 |
38.1 |
** |
|||
0.01 |
0.010 |
20.7 |
34.2 |
45.1 |
** |
|
16.4 |
42.2 |
41.5 |
** |
|||
St. Triphon |
1.0 |
1.005 |
26.0 |
14.0 |
60.0 |
** |
25.3 |
14.0 |
60.7 |
** |
|||
0.5 |
0.506 |
23.1 |
11.3 |
65.6 |
** |
|
23.5 |
11.5 |
65.0 |
** |
|||
0.1 |
0.102 |
19.1 |
11.5 |
69.4 |
** |
|
17.9 |
13.2 |
68.9 |
** |
|||
0.05 |
0.051 |
17.4 |
11.8 |
70.8 |
** |
|
17.6 |
9.6 |
72.8 |
** |
|||
0.01 |
0.010 |
15.8 |
6.2 |
78.0 |
** |
|
16.5 |
7.6 |
75.9 |
** |
|||
Hepler |
1.0 |
1.005 |
18.9 |
27.5 |
53.5 |
** |
22.1 |
17.9 |
60.0 |
** |
|||
0.5 |
0.506 |
20.5 |
16.1 |
63.4 |
** |
|
21.0 |
13.2 |
65.8 |
** |
|||
0.1 |
0.102 |
16.0 |
12.0 |
72.0 |
** |
|
17.0 |
35.7 |
47.3 |
** |
|||
0.05 |
0.051 |
13.8 |
10.8 |
75.4 |
** |
|
15.8 |
12.3 |
71.9 |
** |
|||
0.01 |
0.010 |
13.1 |
9.4 |
77.5 |
** |
|
14.0 |
9.1 |
76.9 |
** |
|||
Soilless control |
1.0 |
1.005 |
25.0 |
77.6 |
n.a. |
102.6 |
9.8 |
92.3 |
n.a. |
102.1 |
|||
0.5 |
0.506 |
27.9 |
74.5 |
n.a. |
102.3 |
|
27.0 |
75.0 |
n.a. |
102.1 |
|||
0.1 |
0.102 |
33.6 |
66.3 |
n.a. |
99.9 |
|
40.7 |
60.5 |
n.a. |
101.2 |
|||
0.05 |
0.051 |
43.5 |
59.1 |
n.a. |
102.6 |
|
64.3 |
36.8 |
n.a. |
101.1 |
|||
0.01 |
0.010 |
62.3 |
38.5 |
n.a. |
100.8 |
|
79.2 |
22.8 |
n.a. |
102.0 |
|||
* Percentage of radioactivity adsorbed to soil after adsorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after adsorption.
** 100% by definition as the indirect method was used to calculate the percentage of radioactivity adsorbed to soil.
n.a. Not applicable for soilless control samples.
Table 4. Analysis of 14C-labelled test substance
Adsorption/Desorption test |
||||
Soil |
Nominal concentration (µg/ml) |
% the test substance of HPLC/TLC chromatogram |
||
% in adsorption supernatant |
% in desorption supernatant |
% in soil extract |
||
Ushiku Japanese Ash |
1.0 |
≥ 98.3* |
100.0 |
≥ 98.7* |
St. Triphon |
1.0 |
100.0 |
100.0 |
≥ 98.2* |
Hepler |
1.0 |
≥ 97.5* |
≥ 97.1* |
≥ 98.4* |
Hepler |
0.5 |
100.0 |
100.0 |
≥ 98.0* |
Hepler |
0.1 |
100.0 |
100.0 |
100.0 |
Hepler |
0.05 |
98.4 |
99.3 |
100.0 |
Hepler |
0.01 |
n.a. |
n.a. |
100.0 |
n.a Not analysed due to low amount of radioactivity in sample.
* Lowest value of duplicate samples
Table 5. Concentrations of the test substance Equivalents for the Adsorption and Desorption Isotherms for Ushiku Japanese Ash Soil
a) Adsorption only test:
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
1.005 |
A |
0.3795 |
38.83 |
38.6 |
B |
0.3673 |
37.61 |
37.4 |
||
Mean |
0.3734 |
38.22 |
38.0 |
||
0.5 |
0.506 |
A |
0.1614 |
22.25 |
44.0 |
B |
0.1580 |
18.90 |
37.4 |
||
Mean |
0.1597 |
20.58 |
40.7 |
||
0.1 |
0.102 |
A |
0.0209 |
3.77 |
37.0 |
B |
0.0219 |
4.13 |
40.5 |
||
Mean |
0.0214 |
3.95 |
38.8 |
||
0.05 |
0.051 |
A |
0.0104 |
2.25 |
44.3 |
B |
0.0096 |
1.94 |
38.1 |
||
Mean |
0.0100 |
2.10 |
41.2 |
||
0.01 |
0.010 |
A |
0.0021 |
0.47 |
45.1 |
B |
0.0017 |
0.43 |
41.5 |
||
Mean |
0.0019 |
0.45 |
43.3 |
||
b) Adsorption/Desorption test:
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
|
Adsorption/Desorption test |
|
|
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
1.005 |
A |
0.2876 |
0.1826 |
42.70 |
42.5 |
B |
0.2911 |
0.1962 |
41.97 |
41.8 |
||
Mean |
0.2893 |
0.1894 |
42.34 |
42.1 |
||
0.5 |
0.506 |
A |
0.1624 |
0.0870 |
19.16 |
37.9 |
B |
0.1421 |
0.0914 |
20.88 |
41.3 |
||
Mean |
0.1522 |
0.0892 |
20.02 |
39.6 |
||
0.1 |
0.102 |
A |
0.0265 |
0.0187 |
4.67 |
45.9 |
B |
0.0261 |
0.0176 |
4.65 |
45.7 |
||
Mean |
0.0263 |
0.0182 |
4.66 |
45.8 |
||
0.05 |
0.051 |
A |
0.0129 |
0.0083 |
2.22 |
43.6 |
B |
0.0131 |
0.0089 |
2.26 |
44.4 |
||
Mean |
0.0130 |
0.0086 |
2.24 |
44.0 |
||
0.01 |
0.010 |
A |
0.0025 |
0.0016 |
0.53 |
51.8 |
B |
0.0025 |
0.0019 |
0.53 |
51.1 |
||
Mean |
0.0025 |
0.0018 |
0.53 |
51.5 |
||
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by the test facility's measurement.
Caq(des): Concentration of test item in aqueous solution after desorption, as determined by the test facility's measurement.
Cs(des): Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption.
* % of test item remaining adsorbed to soil based on the amount of test item initially applied.
Table 6. Concentrations of the test substance Equivalents for the Adsorption and Desorption Isotherms for St. Triphon Soil
a) Adsorption only test
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
1.005 |
A |
0.2611 |
60.30 |
60.0 |
B |
0.2543 |
61.02 |
60.7 |
||
Mean |
0.2577 |
60.66 |
60.3 |
||
0.5 |
0.506 |
A |
0.1169 |
33.16 |
65.6 |
B |
0.1187 |
32.87 |
65.0 |
||
Mean |
0.1178 |
33.01 |
65.3 |
||
0.1 |
0.102 |
A |
0.0194 |
7.07 |
69.4 |
B |
0.0182 |
7.02 |
68.9 |
||
Mean |
0.0188 |
7.04 |
69.2 |
||
0.05 |
0.051 |
A |
0.0088 |
3.60 |
70.8 |
B |
0.0089 |
3.70 |
72.8 |
||
Mean |
0.0089 |
3.65 |
71.8 |
||
0.01 |
0.010 |
A |
0.0016 |
0.81 |
78.0 |
B |
0.0017 |
0.78 |
75.9 |
||
Mean |
0.0017 |
0.79 |
76.9 |
||
b) Adsorption/Desorption test
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
|
Adsorption/Desorption test |
|
|
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
1.005 |
A |
0.2632 |
0.1697 |
47.87 |
47.6 |
B |
0.2695 |
0.1607 |
48.26 |
48.0 |
||
Mean |
0.2664 |
0.1652 |
48.07 |
47.8 |
||
0.5 |
0.506 |
A |
0.1256 |
0.0736 |
25.35 |
50.1 |
B |
0.1233 |
0.0750 |
25.76 |
50.9 |
||
Mean |
0.1244 |
0.0743 |
25.55 |
50.5 |
||
0.1 |
0.102 |
A |
0.0192 |
0.0135 |
5.97 |
58.6 |
B |
0.0197 |
0.0138 |
5.93 |
58.3 |
||
Mean |
0.0195 |
0.0136 |
5.95 |
58.4 |
||
0.05 |
0.051 |
A |
0.0088 |
0.0067 |
3.30 |
64.9 |
B |
0.0084 |
0.0068 |
3.15 |
62.0 |
||
Mean |
0.0086 |
0.0068 |
3.23 |
63.4 |
||
0.01 |
0.010 |
A |
0.0015 |
0.0012 |
0.70 |
67.8 |
B |
0.0016 |
0.0012 |
0.71 |
68.8 |
||
Mean |
0.0015 |
0.0012 |
0.71 |
68.3 |
||
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by the test facility’s measurement.
Caq(des): Concentration of test item in aqueous solution after desorption, as determined by the test facility’s measurement.
Cs(des): Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption.
* % of test item remaining adsorbed to soil based on the amount of test item initially applied.
Table 7. Concentrations of the test substance Equivalents for the Adsorption and Desorption Isotherms for Hepler Soil
a) Adsorption only test
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
1.018 |
A |
0.1928 |
54.52 |
53.5 |
B |
0.2248 |
61.15 |
60.0 |
||
Mean |
0.2088 |
57.84 |
56.8 |
||
0.5 |
0.508 |
A |
0.1040 |
32.18 |
63.4 |
B |
0.1065 |
33.42 |
65.8 |
||
Mean |
0.1052 |
32.80 |
64.6 |
||
0.1 |
0.101 |
A |
0.0162 |
7.30 |
72.0 |
B |
0.0172 |
4.79** |
47.3** |
||
Mean |
0.0167 |
6.05 |
59.7 |
||
0.05 |
0.051 |
A |
0.0070 |
3.82 |
75.4 |
B |
0.0080 |
3.64 |
71.9 |
||
Mean |
0.0075 |
3.73 |
73.7 |
||
0.01 |
0.010 |
A |
0.0014 |
0.80 |
77.5 |
B |
0.0014 |
0.79 |
76.9 |
||
Mean |
0.0014 |
0.80 |
77.2 |
||
b) Adsorption/Desorption test
Nominal Test Concentration (µg/mL) |
Actual Concentration Achieved (µg/mL) |
Replicate |
Adsorption/Desorption test |
|||
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
1.018 |
A |
0.2069 |
0.1429 |
59.46 |
58.4 |
|
|
B |
0.2128 |
0.1463 |
57.73 |
56.7 |
|
|
Mean |
0.2098 |
0.1446 |
58.59 |
57.5 |
0.5 |
0.508 |
A |
0.1028 |
0.0734 |
30.26 |
59.6 |
|
|
B |
0.0980 |
0.0728 |
29.75 |
58.6 |
|
|
Mean |
0.1004 |
0.0731 |
30.01 |
59.1 |
0.1 |
0.101 |
A |
0.0161 |
0.0125 |
6.44 |
63.5 |
|
|
B |
0.0157 |
0.0130 |
6.45 |
63.6 |
|
|
Mean |
0.0159 |
0.0128 |
6.44 |
63.6 |
0.05 |
0.051 |
A |
0.0079 |
0.0061 |
3.39 |
66.9 |
|
|
B |
0.0072 |
0.0057 |
3.36 |
66.3 |
|
|
Mean |
0.0075 |
0.0059 |
3.37 |
66.6 |
0.01 |
0.010 |
A |
0.0013 |
0.0010 |
0.72 |
69.8 |
|
|
B |
0.0013 |
0.0010 |
0.76 |
73.1 |
|
|
Mean |
0.0013 |
0.0010 |
0.74 |
71.5 |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by the test facility’s measurement.
Caq(des): Concentration of test item in aqueous solution after desorption, as determined by the test facility’s measurement.
Cs(des): Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption.
* % of test item remaining adsorbed to soil based on the amount of test item initially applied.
Table 8.Soil adsorption constants for the test substance in 3 Soils
Parameter |
Ushiku Japanese Ash |
St. Triphon |
Hepler |
Texture |
Sandy loam |
Clay loam |
Silt loam |
pH (0.01M CaCl2)* |
5.33 |
7.43 |
6.02 |
%OC |
1.9 |
3.7 |
3.0 |
Adsorption |
|||
KF (mL/g) (95% confidence intervals) |
93.5 (81.7 - 107.0) |
204 (187.1 - 222.8) |
218 (168.0 - 282.3) |
KFOC (mL/g) |
4’921 |
5’518 |
7’260 |
1/n (95% confidence intervals) |
0.840 (0.806-0.873) |
0.860 (0.838-0.881) |
0.851 (0.791-0.912) |
r2 |
0.9976 |
0.9991 |
0.9924 |
Kd (averaged) (mL/g) |
172.1 |
355.4 |
405.4 |
KOC (averaged) (mL/g) |
9’059 |
9’605 |
13’512 |
% absorbed |
37.0 - 45.1 |
60.0 - 78.0 |
47.3 - 77.5 |
Kd × (soil:solution ratio) |
1.023-2.536 |
2.309-4.937 |
2.721-5.936 |
Desorption |
|||
KF (mL/g) (95% confidence intervals) |
195 (174.1-218.1) |
234 (218.0-251.6) |
305 (282.0-330.3) |
KFOC (mL/g) |
10’255 |
6’329 |
10’173 |
1/n (95% confidence intervals) |
0.933 (0.906-0.960) |
0.860 (0.844-0.876) |
0.876 (0.859-0.894) |
r2 |
0.9987 |
0.9995 |
0.9994 |
Kd (indirect method)/Kd (direct method)** |
1.08 |
1.01 |
1.03 |
Kd (averaged) (mL/g) |
253.9 |
427.0 |
526.0 |
KOC (averaged) (mL/g) |
13’365 |
11’542 |
17’533 |
% absorbed |
37.9 - 51.8 |
47.6 - 68.8 |
56.7 - 73.1 |
Kd × (soil:solution ratio) |
2.140 - 3.362 |
2.820 - 6.042 |
3.947 - 7.581 |
Mass balance*** (average) (%) |
100.9 |
102.0 |
102.0 |
* Determined during the course of the study.
** Averaged ratio derived from the highest test concentration. Kd (direct method) was calculated based on the amount of radioactivity extracted from soils (mass balance samples).
*** Recovery of applied radioactivity.
Table 3. Mass Balance
a)
Adsorption only test |
||||||||
Soil |
Nominal concentration (mg/L) |
Actual concentration achieved (mg/L) |
Adsorption supernatant (%) |
Soil transfer solution (%) |
Tube rinsing solution (%) |
Soil extract (%) |
Unextracted residues (%) |
Total Recovery (%) |
Latossolo |
1.0 |
0.980 |
24.8 |
3.9 |
24.1 |
20.7 |
0.2 |
73.7* |
25.0 |
2.0 |
17.7 |
55.9 |
0.4 |
101.0 |
|||
Argissolo |
1.0 |
0.980 |
21.6 |
1.8 |
31.7 |
44.9 |
0.9 |
100.9 |
23.1 |
2.4 |
24.4 |
50.2 |
1.0 |
101.2 |
|||
Gleissolo |
1.0 |
0.980 |
11.7 |
1.1 |
15.3 |
68.5 |
0.6 |
97.3 |
12.7 |
1.4 |
12.9 |
72.8 |
0.7 |
100.5 |
|||
Gleissolo |
0.5 |
0.482 |
11.7 |
1.2 |
21.9 |
64.7 |
0.6 |
100.0 |
12.9 |
1.2 |
20.2 |
64.4 |
0.6 |
99.3 |
|||
Gleissolo |
0.1 |
0.089 |
10.4 |
1.3 |
21.3 |
83.8 |
0.9 |
117.7* |
9.1 |
1.2 |
8.5 |
86.6 |
1.0 |
106.4 |
|||
Gleissolo |
0.05 |
0.048 |
8.5 |
0.9 |
18.1 |
52.0 |
1.1 |
80.6* |
9.4 |
0.9 |
13.5 |
77.0 |
1.0 |
101.8 |
|||
Gleissolo |
0.01 |
0.010 |
7.6 |
0.8 |
11.2 |
79.9 |
1.2 |
100.7 |
8.0 |
0.8 |
9.3 |
80.1 |
1.1 |
99.3 |
|||
Neossolo |
1.0 |
0.980 |
28.4 |
2.2 |
28.2 |
39.9 |
0.1 |
98.9 |
28.6 |
2.4 |
22.7 |
42.8 |
0.2 |
96.8 |
|||
Soilless control |
1.0 |
0.980 |
5.8 |
n.p. |
101.8 |
n.p. |
n.p. |
107.6 |
6.4 |
n.p |
99.6 |
n.p. |
n.p. |
106.0 |
|||
Soilless control |
0.5 |
0.482 |
8.8 |
n.p. |
99.4 |
n.p. |
n.p. |
108.2 |
15.0 |
n.p. |
90.5 |
n.p. |
n.p. |
105.5 |
|||
Soilless control |
0.1 |
0.089 |
44.6 |
n.p. |
76.1 |
n.p. |
n.p. |
120.7* |
42.4 |
n.p. |
76.6 |
n.p. |
n.p. |
119.0* |
|||
Soilless control |
0.05 |
0.048 |
54.8 |
n.p. |
52.5 |
n.p. |
n.p. |
107.3 |
58.0 |
n.p. |
49.1 |
n.p. |
n.p. |
107.1 |
|||
Soilless control |
0.01 |
0.010 |
60.6 |
n.p. |
37.4 |
n.p. |
n.p. |
97.9 |
70.1 |
n.p. |
36.4 |
n.p. |
n.p. |
106.4 |
|||
* confirmed by LSC re-analysis
n.p. not performed
b)
Adsorption/Desorption test |
|||||||||
Soil |
Nominal concen- tration (mg/L) |
Actual concen- tration achieved (mg/L) |
Adsorption supernatant (%) |
Desorption supernatant# (%) |
Soil transfer solution (%) |
Tube rinsing solution (%) |
Soil extract (%) |
Unextracted residues (%) |
Total Recovery (%) |
Latossolo |
1.0 |
0.990 |
25.7 |
15.6 |
0.8 |
14.8 |
43.9 |
0.3 |
101.1 |
24.7 |
15.5 |
0.8 |
12.9 |
46.7 |
0.4 |
100.9 |
|||
Argissolo |
1.0 |
0.990 |
26.5 |
16.4 |
1.5 |
15.9 |
40.0 |
0.9 |
101.2 |
27.0 |
16.4 |
0.9 |
17.1 |
39.1 |
0.9 |
101.4 |
|||
Gleissolo |
1.0 |
0.990 |
17.8 |
10.1 |
0.8 |
10.0 |
61.0 |
0.9 |
100.5 |
17.2 |
10.1 |
0.8 |
12.5 |
58.7 |
0.8 |
100.1 |
|||
Gleissolo |
0.5 |
0.491 |
14.1 |
8.2 |
0.6 |
9.9 |
67.1 |
1.0 |
101.0 |
13.1 |
8.6 |
0.5 |
11.9 |
65.7 |
0.9 |
100.7 |
|||
Gleissolo |
0.1 |
0.099 |
12.6 |
7.3 |
1.0 |
6.9 |
71.9 |
1.0 |
100.8 |
13.8 |
7.5 |
1.2 |
7.4 |
67.9 |
1.0 |
98.8 |
|||
Gleissolo |
0.05 |
0.050 |
13.2 |
6.9 |
0.6 |
6.9 |
72.0 |
1.2 |
100.8 |
11.6 |
6.5 |
0.8 |
7.0 |
72.8 |
1.2 |
99.8 |
|||
Gleissolo |
0.01 |
0.010 |
10.7 |
6.1 |
0.7 |
6.8 |
74.8 |
1.5 |
100.6 |
11.5 |
7.0 |
0.7 |
6.8 |
74.1 |
1.2 |
101.3 |
|||
Neossolo |
1.0 |
0.990 |
29.8 |
16.7 |
0.9 |
14.0 |
38.9 |
0.2 |
100.5 |
32.3 |
16.9 |
1.3 |
12.3 |
38.0 |
0.3 |
101.0 |
|||
Soilless control |
1.0 |
0.990 |
43.8 |
n.p. |
n.p. |
59.1 |
n.p. |
n.p. |
102.9 |
31.6 |
n.p. |
n.p. |
70.8 |
n.p. |
n.p. |
102.3 |
|||
Soilless control |
0.5 |
0.491 |
19.2 |
n.p. |
n.p. |
83.5 |
n.p. |
n.p. |
102.7 |
44.1 |
n.p. |
n.p. |
58.5 |
n.p. |
n.p. |
102.6 |
|||
Soilless control |
0.1 |
0.099 |
35.3 |
n.p. |
n.p. |
67.3 |
n.p. |
n.p. |
102.6 |
34.5 |
n.p. |
n.p. |
68.0 |
n.p. |
n.p. |
102.5 |
|||
Soilless control |
0.05 |
0.050 |
43.7 |
n.p. |
n.p. |
58.3 |
n.p. |
n.p. |
102.0 |
36.3 |
n.p. |
n.p. |
64.7 |
n.p. |
n.p. |
101.1 |
|||
Soilless control |
0.01 |
0.010 |
56.6 |
n.p. |
n.p. |
44.1 |
n.p. |
n.p. |
100.7 |
72.0 |
n.p. |
n.p. |
27.9 |
n.p. |
n.p. |
99.9 |
|||
# corrected for residual water after adsorption
n.p. not performed
Table 4. Analysis of 14C-labelled test substance
a)
Adsorption only test |
|||
Soil |
Nominal Concentration (mg/L) |
% the test substance of HPLC/TLCachromatogram |
|
% in adsorption supernatant |
% in soil extract |
||
Latossolo |
1.0 |
100 |
100 |
Argissolo |
1.0 |
100 |
100 |
Gleissolo |
1.0 |
100 |
≥ 97.9* |
Gleissolo |
0.5 |
100 |
≥ 97.8* |
Gleissolo |
0.1 |
≥ 92.9*a |
100 |
Gleissolo |
0.05 |
n.a. |
100 |
Gleissolo |
0.01 |
n.a. |
≥ 99.3*a |
Neossolo |
1.0 |
100 |
100 |
b)
Adsorption/Desorption test |
||||
Soil |
Nominal Concentration (mg/L) |
% the test substance of HPLC/TLCa chromatogram
|
||
% in adsorption supernatant |
% in desorption supernatant |
% in soil extract after desorption |
||
Latossolo |
1.0 |
100 |
100 |
≥ 98.6* |
Argissolo |
1.0 |
100 |
100 |
≥ 98.4* |
Gleissolo |
1.0 |
100 |
100 |
≥ 98.2* |
Gleissolo |
0.5 |
n.d. |
100 |
≥ 98.3* |
Gleissolo |
0.1 |
n.d. |
≥ 94.9*a |
100 |
Gleissolo |
0.05 |
n.d. |
≥ 94.7*a |
100 |
Gleissolo |
0.01 |
n.d. |
n.a. |
100a |
Neossolo |
1.01 |
100 |
100 |
≥ 98.9* |
n.d. not determined
n.a. not analysed due to low amount of radioactivity in sample
* lowest value of duplicate samples
a determined by TLC analysis
Table 5. Concentrations of the test substance Equivalents for the Adsorption only and Adsorption/Desorption Isotherms for Latossolo Soil
a) Adsorption only test:
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
0.980 |
A |
0.2434 |
50.05 |
51.1 |
B |
0.2454 |
56.11 |
57.3 |
||
Mean |
0.2444 |
53.08 |
54.2 |
||
0.5 |
0.482 |
A |
0.1056 |
28.06 |
58.2 |
B |
0.0981 |
27.57 |
57.2 |
||
Mean |
0.1018 |
27.82 |
56.5 |
||
0.1 |
0.089 |
A |
0.0187 |
5.054 |
56.8 |
B |
0.0184 |
5.002 |
56.2 |
||
Mean |
0.0186 |
5.028 |
56.5 |
||
0.05 |
0.048 |
A |
0.0086 |
3.092 |
64.8 |
B |
0.0085 |
2.987 |
62.6 |
||
Mean |
0.0085 |
3.040 |
63.7 |
||
0.01 |
0.010 |
A |
0.0016 |
0.701 |
68.8 |
B |
0.0016 |
0.681 |
66.9 |
||
Mean |
0.0016 |
0.691 |
67.9 |
||
b)Adsorption/Desorption test
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption/Desorption test |
|||
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
0.990 |
A |
0.2547 |
0.1568 |
43.49 |
43.9 |
B |
0.2445 |
0.1562 |
46.41 |
46.9 |
||
Mean |
0.2496 |
0.1565 |
44.95 |
45.4 |
||
0.5 |
0.491 |
A |
0.1204 |
0.0735 |
22.56 |
45.9 |
B |
0.1157 |
0.0741 |
23.51 |
47.9 |
||
Mean |
0.1181 |
0.0738 |
23.03 |
46.9 |
||
0.1 |
0.099 |
A |
0.0207 |
0.0136 |
5.154 |
52.2 |
B |
0.0201 |
0.0120 |
5.314 |
53.9 |
||
Mean |
0.0095 |
0.0128 |
5.234 |
53.1 |
||
0.05 |
0.050 |
A |
0.0095 |
0.0058 |
2.896 |
58.2 |
B |
0.0095 |
0.0062 |
2.859 |
57.4 |
||
Mean |
0.0095 |
0.0060 |
2.878 |
57.8 |
||
0.01 |
0.010 |
A |
0.0017 |
0.0011 |
0.601 |
60.5 |
B |
0.0018 |
0.0012 |
0.592 |
59.6 |
||
Mean |
0.0018 |
0.0011 |
0.596 |
60.0 |
||
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by the test facility’s measurement
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by the test facility’s measurement
Cs(ads) Concentration of test item in soil after adsorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after adsorption
Cs(des) Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption
* % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 6. Concentrations of the test substance Equivalents for the Adsorption only and Adsorption/Desorption Isotherms for Argissolo Soil
a) Adsorption only test
Nominal test Concentration (mg/L) |
Actual concentration achieved (mg/L) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
0.980 |
A |
0.2121 |
45.74 |
46.7 |
B |
0.2266 |
51.39 |
52.4 |
||
Mean |
0.2193 |
48.56 |
49.6 |
||
0.5 |
0.482 |
A |
0.1020 |
23.40 |
48.5 |
B |
0.0996 |
24.45 |
50.7 |
||
Mean |
0.1008 |
23.93 |
49.6 |
||
0.1 |
0.089 |
A |
0.0192 |
4.513 |
50.7 |
B |
0.0175 |
4.574 |
51.4 |
||
Mean |
0.0184 |
4.544 |
51.0 |
||
0.05 |
0.048 |
A |
0.0086 |
2.753 |
57.7 |
B |
0.0079 |
2.724 |
57.1 |
||
Mean |
0.0082 |
2.739 |
57.4 |
||
0.01 |
0.010 |
A |
0.0015 |
0.577 |
56.7 |
B |
0.0015 |
0.641 |
63.0 |
||
Mean |
0.0015 |
0.609 |
59.8 |
||
b) Adsorption/Desorption test
Nominal test Concentration (mg/L) |
Actualconcentrationachieved (mg/L) |
Replicate |
|
Adsorption/Desorption test |
|
|
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
0.990 |
A |
0.2618 |
0.1657 |
40.77 |
41.2 |
B |
0.2672 |
0.1657 |
39.10 |
39.5 |
||
Mean |
0.2645 |
0.1657 |
39.94 |
40.4 |
||
0.5 |
0.491 |
A |
0.1136 |
n.a. |
n.a. |
n.a. |
B |
0.1200 |
0.0760 |
20.49 |
41.7 |
||
Mean |
0.1168 |
0.0760 |
20.49 |
41.7 |
||
0.1 |
0.099 |
A |
0.0195 |
0.0134 |
4.994 |
50.6 |
B |
0.0192 |
0.0135 |
5.001 |
50.7 |
||
Mean |
0.0194 |
0.0134 |
4.998 |
50.7 |
||
0.05 |
0.050 |
A |
0.0086 |
0.0060 |
2.809 |
56.4 |
B |
0.0088 |
0.0064 |
2.715 |
54.5 |
||
Mean |
0.0087 |
0.0062 |
2.762 |
55.5 |
||
0.01 |
0.010 |
A |
0.0016 |
0.0011 |
0.581 |
58.5 |
B |
0.0016 |
0.0011 |
0.580 |
58.4 |
||
Mean |
0.0016 |
0.0011 |
0.580 |
58.4 |
||
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by the test facility’s measurement
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by the test facility’s measurement
Cs(ads) Concentration of test item in soil after adsorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after adsorption
Cs(des) Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption
* % of test item remaining adsorbed to soil based on the amount of test item initially applied
n.a. not applicable because of sample loss during preparation
Table 7. Concentrations of the test substance Equivalents for the Adsorption only and Adsorption/Desorption Isotherms for Gleissolo Soil
a) Adsorption only test
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
0.980 |
A |
0.1147 |
71.50 |
73.0 |
B |
0.1242 |
72.90 |
74.4 |
||
Mean |
0.1195 |
72.20 |
73.7 |
||
0.5 |
0.482 |
A |
0.0562 |
32.04 |
66.4 |
B |
0.0621 |
32.27 |
66.9 |
||
Mean |
0.0591 |
32.15 |
66.7 |
||
0.1 |
0.089 |
A |
0.0093 |
6.082 |
68.3 |
B |
0.0081 |
7.337 |
82.4 |
||
Mean |
0.0087 |
6.709 |
75.3 |
||
0.05 |
0.048 |
A |
0.0041 |
3.503 |
73.4 |
B |
0.0045 |
3.676 |
77.1 |
||
Mean |
0.0043 |
3.590 |
75.2 |
||
0.01 |
0.010 |
A |
0.0008 |
0.827 |
81.3 |
B |
0.0008 |
0.842 |
82.7 |
||
Mean |
0.0008 |
0.835 |
82.0 |
||
b) Adsorption/desorption test
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption/Desorption test |
|||
Caq(ads) (µg/mL) |
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
0.990 |
A |
0.1759 |
0.1021 |
71.39 |
62.1 |
B |
0.1700 |
0.1024 |
71.95 |
60.2 |
||
Mean |
0.1730 |
0.1022 |
71.67 |
61.2 |
||
0.5 |
0.491 |
A |
0.0694 |
0.0412 |
38.14 |
67.8 |
B |
0.0642 |
0.0431 |
38.46 |
66.4 |
||
Mean |
0.0668 |
0.0421 |
38.30 |
67.1 |
||
0.1 |
0.099 |
A |
0.0124 |
0.0074 |
7.902 |
73.2 |
B |
0.0137 |
0.0076 |
7.756 |
71.3 |
||
Mean |
0.0130 |
0.0075 |
7.829 |
72.2 |
||
0.05 |
0.050 |
A |
0.0065 |
0.0035 |
3.979 |
73.0 |
B |
0.0058 |
0.0033 |
4.082 |
75.0 |
||
Mean |
0.0062 |
0.0034 |
4.030 |
74.0 |
||
0.01 |
0.010 |
A |
0.0011 |
0.0006 |
0.826 |
76.4 |
B |
0.0011 |
0.0007 |
0.809 |
74.7 |
||
Mean |
0.0011 |
0.0007 |
0.818 |
75.6 |
||
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined bythe test facility’smeasurement
Caq(des) Concentration of test item in aqueous solution after desorption, as determined bythe test facility’smeasurement
Cs(ads) Concentration of test item in soil after adsorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after adsorption
Cs(des) Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption
* % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 8. Concentrations of the test substance Equivalents for the Adsorption only and Adsorption/Desorption Isotherms for Neossolo Soil
a) Adsorption only test
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption only test |
||
Caq(ads) (µg/mL) |
Cs(ads) (µg/g) |
% adsorbed* |
|||
1.0 |
0.980 |
A |
0.2782 |
21.26 |
43.4 |
B |
0.2804 |
23.84 |
48.6 |
||
Mean |
0.2793 |
22.55 |
46.0 |
||
0.5 |
0.482 |
A |
0.1196 |
13.15 |
54.5 |
B |
0.1445 |
12.97 |
53.8 |
||
Mean |
0.1320 |
13.06 |
54.2 |
||
0.1 |
0.089 |
A |
0.0212 |
2.455 |
55.1 |
B |
0.0230 |
2.425 |
54.5 |
||
Mean |
0.0221 |
2.440 |
54.8 |
||
0.05 |
0.048 |
A |
0.0085 |
1.486 |
62.3 |
B |
0.0113 |
1.342 |
56.2 |
||
Mean |
0.0099 |
1.414 |
59.3 |
||
0.01 |
0.010 |
A |
0.0019 |
0.331 |
65.0 |
B |
0.0020 |
0.326 |
64.1 |
||
Mean |
0.0020 |
0.329 |
64.6 |
||
b) Adsorption/Desorption test
Nominal test concentration (mg/L) |
Actual test concentration achieved (mg/L) |
Replicate |
Adsorption/Desorption test |
|||
Caq(ads) (µg/mL)
|
Caq(des) (µg/mL) |
Cs(des) (µg/g) |
% adsorbed* |
|||
1.0 |
0.990 |
A |
0.2947 |
0.1685 |
26.47 |
39.5 |
B |
0.3195 |
0.1706 |
25.14 |
38.6 |
||
Mean |
0.3071 |
0.1695 |
25.81 |
39.0 |
||
0.5 |
0.491 |
A |
0.1203 |
0.0765 |
14.77 |
50.1 |
B |
0.1308 |
0.0780 |
14.19 |
43.1 |
||
Mean |
0.1256 |
0.0772 |
14.48 |
46.6 |
||
0.1 |
0.099 |
A |
0.0268 |
0.0159 |
2.809 |
46.6 |
B |
0.0190 |
0.0128 |
3.352 |
55.6 |
||
Mean |
0.0229 |
0.0144 |
3.081 |
51.1 |
||
0.05 |
0.050 |
A |
0.0106 |
0.0071 |
1.608 |
51.2 |
B |
0.0114 |
0.0079 |
1.532 |
50.2 |
||
Mean |
0.0110 |
0.0075 |
1.570 |
50.7 |
||
0.01 |
0.010 |
A |
0.0022 |
0.0015 |
0.311 |
50.0 |
B |
0.0023 |
0.0014 |
0.310 |
48.3 |
||
Mean |
0.0023 |
0.0014 |
0.311 |
49.2 |
||
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by the test facility’s measurement
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by the test facility’s measurement
Cs(ads) Concentration of test item in soil after adsorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after adsorption
Cs(des) Concentration of test item in soil after desorption, as determined by the indirect method, excluding the amount adsorbed to the vessel wall after desorption
* % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 9. Soil adsorption and desorption constants for the test substance in 4 Soils
Parameter |
Latossolo |
Argissolo |
Gleissolo |
Neossolo |
Texture |
Sandy clay |
Sandy clay loam |
Loamy sand |
Sand |
pH (0.01M CaCl2)* |
4.4 |
5.6 |
4.4 |
4.8 |
%OC |
2.7 |
2.4 |
10.2 |
0.78 |
Adsorption (from the adsorption only test) |
||||
KF (mL/g) |
186 |
175 |
422 |
69 |
KFOC (mL/g) |
6’899 |
7’291 |
4’140 |
8’902 |
1/n |
0.873 |
0.875 |
0.874 |
0.857 |
R2 |
0.9973 |
0.9969 |
0.9964 |
0.9949 |
Kd (averaged) mL/g |
310 |
290 |
764 |
121 |
KOC (averaged) mL/g |
11’473 |
12’095 |
7’490 |
15’472 |
Desorption (from the adsorption/desorption test) |
||||
KF (mL/g) |
227 |
183 |
601 |
148 |
KFOC (mL/g) |
8’400 |
7’626 |
5’890 |
18’987 |
1/n |
0.868 |
0.838 |
0.892 |
0.932 |
R2 |
0.9984 |
0.9990 |
0.9976 |
0.9945 |
Kd (averaged) mL/g |
404 |
382 |
1’015 |
197 |
KOC (averaged) mL/g |
14’959 |
15’907 |
9’947 |
25’241 |
* determined during the course of the study
Table 7. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for Seven Springs Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
| Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | |
1.0 | A | 0.438 | 20.355 | 46.1 |
B | 0.416 | 21.004 | 47.6 | |
0.5 | A | 0.184 | 10.873 | 48.4 |
B | 0.183 | 10.347 | 46.1 | |
0.1 | A | 0.036 | 2.667 | 52.4 |
B | 0.031 | 2.703 | 53.2 | |
0.05 | A | 0.016 | 1.226 | 54.2 |
B | 0.015 | 1.253 | 55.4 | |
0.01 | A | 0.002 | 0.278 | 59.3 |
B | 0.002 | 0.303 | 64.8 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads): Concentration of test item in soil after adsorption, as determined by “direct method "extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.451 | 0.174 | 12.115 | 26.9 |
B | 0.444 | 0.177 | 12.048 | 26.7 | |
0.5 | A | 0.173 | 0.088 | 6.558 | 29.2 |
B | 0.182 | 0.090 | 7.289 | 32.5 | |
0.1 | A | 0.038 | 0.022 | 1.750 | 33.0 |
B | 0.036 | 0.021 | 1.843 | 34.8 | |
0.05 | A | 0.016 | 0.010 | 0.866 | 37.6 |
B | 0.016 | 0.009 | 0.869 | 37.7 | |
0.01 | A | 0.003 | 0.002 | 0.198 | 42.8 |
B | 0.003 | 0.002 | 0.197 | 42.6 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 8. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for 18 Acres Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | ||
1.0 | A | 0.235 | 60.599 | 68.6 |
B | 0.242 | 59.005 | 66.8 | |
0.5 | A | 0.104 | 31.230 | 69.5 |
B | 0.102 | 31.680 | 70.6 | |
0.1 | A | 0.019 | 7.273 | 71.5 |
B | 0.021 | 7.324 | 72.0 | |
0.05 | A | 0.009 | 3.405 | 75.3 |
B | 0.009 | 3.384 | 74.8 | |
0.01 | A | 0.002 | 0.690 | 73.7 |
B | 0.002 | 0.661 | 70.6 | |
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads) Concentration of test item in soil after adsorption, as determined by “direct method" extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.255 | 0.138 | 47.465 | 52.6 |
B | 0.244 | 0.145 | 46.715 | 51.8 | |
0.5 | A | 0.112 | 0.071 | 24.878 | 53.5 |
B | 0.106 | 0.069 | 25.765 | 55.4 | |
0.1 | A | 0.024 | 0.014 | 6.089 | 57.5 |
B | 0.020 | 0.014 | 6.366 | 60.1 | |
0.05 | A | 0.009 | 0.006 | 2.845 | 61.7 |
B | 0.009 | 0.006 | 2.824 | 61.3 | |
0.01 | A | 0.002 | 0.001 | 0.621 | 67.2 |
B | 0.002 | 0.001 | 0.612 | 66.2 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 9. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for Capay Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | ||
1.0 | A | 0.303 | 25.124 | 56.9 |
B | 0.373 | 22.260 | 50.4 | |
0.5 | A | 0.148 | 12.193 | 54.3 |
B | 0.161 | 11.842 | 52.7 | |
0.1 | A | 0.025 | 3.265 | 64.2 |
B | 0.028 | 3.063 | 60.2 | |
0.05 | A | 0.011 | 1.466 | 64.8 |
B | 0.011 | 1.471 | 65.1 | |
0.01 | A | 0.003 | 0.273 | 58.4 |
B | 0.003 | 0.283 | 60.5 | |
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads) Concentration of test item in soil after adsorption, as determined by “direct method" extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.451 | 0.088 | 15.874 | 35.2 |
B | 0.444 | 0.090 | 15.920 | 35.3 | |
0.5 | A | 0.153 | 0.080 | 8.238 | 35.4 |
B | 0.166 | 0.085 | 7.986 | 34.3 | |
0.1 | A | 0.030 | 0.019 | 2.218 | 41.9 |
B | 0.034 | 0.019 | 2.115 | 39.9 | |
0.05 | A | 0.015 | 0.009 | 0.953 | 41.3 |
B | 0.014 | 0.009 | 1.033 | 44.8 | |
0.01 | A | 0.002 | 0.002 | 0.206 | 44.5 |
B | 0.002 | 0.002 | 0.211 | 45.5 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 10. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for Sarpy Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | ||
1.0 | A | 0.379 | 47.056 | 53.3 |
B | 0.333 | 48.272 | 54.7 | |
0.5 | A | 0.165 | 24.835 | 55.3 |
B | 0.146 | 25.509 | 56.8 | |
0.1 | A | 0.028 | 5.807 | 57.1 |
B | 0.033 | 6.336 | 62.3 | |
0.05 | A | 0.014 | 2.697 | 59.6 |
B | 0.013 | 2.609 | 57.7 | |
0.01 | A | 0.002 | 0.557 | 59.6 |
B | 0.002 | 0.633 | 67.6 | |
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads) Concentration of test item in soil after adsorption, as determined by “direct method" extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.368 | 0.167 | 30.216 | 33.5 |
B | 0.359 | 0.168 | 31.317 | 34.7 | |
0.5 | A | 0.154 | 0.083 | 16.242 | 34.9 |
B | 0.160 | 0.085 | 16.720 | 35.9 | |
0.1 | A | 0.031 | 0.018 | 4.546 | 42.9 |
B | 0.032 | 0.018 | 4.657 | 43.9 | |
0.05 | A | 0.016 | 0.008 | 1.956 | 42.4 |
B | 0.016 | 0.008 | 1.931 | 41.9 | |
0.01 | A | 0.003 | 0.002 | 0.467 | 50.5 |
B | 0.002 | 0.002 | 0.469 | 50.7 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 11. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for East Anglia Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | ||
1.0 | A | 0.336 | 48.021 | 54.4 |
B | 0.338 | 45.52 | 51.6 | |
0.5 | A | 0.156 | 25.831 | 57.5 |
B | 0.141 | 26.225 | 58.4 | |
0.1 | A | 0.033 | 6.124 | 60.2 |
B | 0.032 | 6.281 | 61.8 | |
0.05 | A | 0.014 | 2.827 | 62.5 |
B | 0.013 | 2.928 | 64.8 | |
0.01 | A | 0.003 | 0.610 | 65.2 |
B | 0.002 | 0.606 | 64.8 | |
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads) Concentration of test item in soil after adsorption, as determined by “direct method" extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.351 | 0.173 | 32.876 | 36.5 |
B | 0.354 | 0.175 | 29.001 | 32.2 | |
0.5 | A | 0.142 | 0.084 | 19.428 | 41.8 |
B | 0.156 | 0.081 | 18.543 | 39.9 | |
0.1 | A | 0.034 | 0.018 | 4.676 | 44.1 |
B | 0.030 | 0.018 | 5.070 | 47.9 | |
0.05 | A | 0.014 | 0.008 | 2.221 | 48.2 |
B | 0.014 | 0.008 | 2.245 | 48.7 | |
0.01 | A | 0.002 | 0.002 | 0.551 | 59.6 |
B | 0.002 | 0.002 | 0.518 | 56.0 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Table 12. Concentrations of the 14C-labelled test substance Equivalents for the Adsorption and Desorption Isotherms for Gartenacker Soil
(a) Adsorption only test:
Nominal test concentration (µg/mL) | Replicate | Adsorption only test | ||
Caq(ads) (µg/mL) | Cs(ads) (µg/g) | % adsorbed to soil (direct method) | ||
1.0 | A | 0.330 | 48.752 | 55.2 |
B | 0.336 | 49.908 | 56.5 | |
0.5 | A | 0.157 | 24.196 | 53.9 |
B | 0.152 | 25.567 | 56.9 | |
0.1 | A | 0.031 | 6.474 | 63.7 |
B | 0.029 | 6.544 | 64.3 | |
0.05 | A | 0.013 | 2.890 | 63.9 |
B | 0.014 | 2.889 | 63.9 | |
0.01 | A | 0.003 | 0.662 | 70.7 |
B | 0.002 | 0.625 | 66.8 | |
Caq(ads) Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Cs(ads) Concentration of test item in soil after adsorption, as determined by “direct method" extraction and by LSC measurement.
(b) Adsorption/Desorption test:
Nominal test concentration (µg/mL) | Replicate | Adsorption / Desorption test | |||
Caq(ads) (µg/mL) | Caq(des) (µg/mL) | Cs(des) (µg/g) | % remaining adsorbed (direct method) | ||
1.0 | A | 0.360 | 0.178 | 34.875 | 38.7 |
B | 0.352 | 0.171 | 35.136 | 39.0 | |
0.5 | A | 0.159 | 0.085 | 18.968 | 40.8 |
B | 0.156 | 0.084 | 19.182 | 41.2 | |
0.1 | A | 0.030 | 0.020 | 4.978 | 47.0 |
B | 0.031 | 0.020 | 4.929 | 46.5 | |
0.05 | A | 0.015 | 0.009 | 2.137 | 46.4 |
B | 0.014 | 0.009 | 2.226 | 48.3 | |
0.01 | A | 0.002 | 0.002 | 0.485 | 52.5 |
B | 0.002 | 0.002 | 0.502 | 54.3 | |
Caq(ads): Concentration of test item in aqueous solution after adsorption, as determined by LSC measurement.
Caq(des) Concentration of test item in aqueous solution after desorption, as determined by LSC measurement. Data from Adsorption followed by desorption test.
Cs(des) Concentration of test item in soil after desorption, as determined by the “direct method” extraction by LSC measurement. Data from Adsorption followed by desorption test.
*: % of test item remaining adsorbed to soil based on the amount of test item initially applied
Description of key information
Average Log Koc = 3.84 (Koc = 6961 L/kg) based on three studies covering 13 soils, equilibrium batch method, OECD TG 106, Williams 2019, Caviezel 2020 and Völkel 2019.
Key value for chemical safety assessment
- Koc at 20 °C:
- 6 961
Additional information
USDA | Name / Origin | OC [%] | pH | Kf [L/kg] | Kfoc [L/kg] | 1/n | Author / Year |
Loamy sand | North Carolina, USA | 0.54 | 5.2 | 42 | 7795 | 0.824 | Williams 2019 |
Sandy clay loam | Berkshire, UK | 1.8 | 6.2 | 230 | 12788 | 0.897 | Williams 2019 |
Loam | California, USA | 0.72 | 6.5 | 67 | 9307 | 0.886 | Williams 2019 |
Loam | Nebraska, USA | 2.2 | 6.5 | 120 | 5451 | 0.865 | Williams 2019 |
Sandy loam | Norfolk, UK | 1.8 | 7 | 133 | 7383 | 0.894 | Williams 2019 |
Loam | Canton Valais, Switzerland | 2 | 7.2 | 132 | 6600 | 0.882 | Williams 2019 |
Sandy loam | Ushiku-shi, Japan | 1.9 | 5.33 | 93.5 | 4921 | 0.840 | Caviezel 2020 |
Clay loam | Ollon, Switzerland | 3.7 | 7.43 | 204 | 5518 | 0.860 | Caviezel 2020 |
Silt loam | Kansas,USA | 3 | 6.02 | 218 | 7260 | 0.851 | Caviezel 2020 |
Sandy clay | São Paolo, Brazil | 2.7 | 4.4 | 186 | 6899 | 0.873 | Völkel 2019 |
Sandy clay loam | São Paolo, Brazil | 2.4 | 5.6 | 175 | 7291 | 0.875 | Völkel 2019 |
Loamy sand | São Paolo, Brazil | 10.2 | 4.4 | 422 | 4140 | 0.874 | Völkel 2019 |
Sand | São Paolo, Brazil | 0.78 | 4.8 | 69 | 8902 | 0.857 | Völkel 2019 |
Arithmetic mean Kfoc |
|
|
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| 6961 |
|
|
The adsorption/desorption coefficient was investigated under GLP to OECD TG 106 in three reliable and valid studies covering a wide variety of soils from Europe, USA, Japan and Brazil using radiolabelled test substance. The tested soils had an organic carbon content ranging from 0.54 to 10.2% and a pH value ranging from 4.4 to 7.43. The experimentally determined Koc ranged from 4140 to 12788 L/kg. The average Koc value was 6961 L/kg (n = 13). The substance is considered to be immobile in soil.
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