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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard OECD test guidelines
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Principles of method if other than guideline:
To determine Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical using HPLC.
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
not specified
Test temperature:
25°C
Details on study design: HPLC method:
HPLC Procedure:
The solutions of the test substance and reference substances were prepared in solvent mentioned in 4.3. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(table 3).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor.

Operating Conditions:
HPLC Model No. : Agilent Technologies,1260 Infinity
Flow Rate : 1.0ml/min
Column : ZORBAX Eclipse Plus C18, 4.6×100mm, 3.5 μm
Mobile phase : ACN : water (55:45)
Temperature : 25°C
Detector : Diode Array Detector @210nm
Injector : Autosampler
Injector volume : 10μl
Data Acquisition software : ChemStationOpen lab Control Panel
Analytical monitoring:
not specified
Details on sampling:
- Concentrations: 400 mg/l
- Sampling interval: A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.8.
Key result
Sample No.:
#1
Type:
log Koc
Value:
3.01 dimensionless
pH:
5.8
Temp.:
25 °C
Remarks on result:
other: LogKoc was reported to be 3.010± 0.000
Details on results (HPLC method):
The Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical was determined to be 3.010± 0.000 at 25°C.
Transformation products:
not specified

Test substance

K

LogK

Log Koc

by Generalized Calibration

Graph

Mean of Log Koc ± S.D.

tR1

4.518

4.094

0.612

3.009

3.010±0.000

tR2

4.520

4.096

0.612

3.010

Validity criteria fulfilled:
yes
Conclusions:
The Adsorption Coefficient of test chemical was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 3.010± 0.000 at 25°C.
Executive summary:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.8. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared . The reference substances were Acetanilide, 4-chloroaniline, 4 -methylaniline (p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4 -Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, N,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 3.010± 0.000 at 25°C. This log Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Description of key information

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.8. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared . The reference substances were Acetanilide, 4-chloroaniline, 4 -methylaniline (p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4 -Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, N,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 3.010± 0.000 at 25°C. This log Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Key value for chemical safety assessment

Additional information

Experimental studies of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from study report (2018),adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.8. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared . The reference substances were Acetanilide, 4-chloroaniline, 4 -methylaniline (p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5 -Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4 -Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, N,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 3.010± 0.000 at 25°C. This log Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

 

For the test chemical from peer reviewed journal (T. Mangialardi et. al., 1990),adsorption study was conducted for evaluating the adsorption capacity of test chemical onto Fuller’s earth at a temperature of 25°C and pH 7.0.The aqueous solutions of test chemical was prepared by using distilled water with a specific conductance less than 2 µmho/cm.Initial conc. of test chemical varies from 25 to 125 mg/dm3. Fuller’s earth was used as an adsorbent material.Prior to use, the earth was dried at 120 °C for 24 hr and sieved into two discrete particle size ranges: 45 to 63 µm and 150 to 180 µm. These two fractions were used as adsorbents and analyzed for mineralogical composition, density, porosity and specific surface area. The mineralogical composition was obtained from X-ray diffraction (XRD) analyses by using a Philips diffractometer with Cu Kα radiation. The solid density(Ps)and porosity (ϵ) were determined with a picnometer (for solids) and a Mercury porosimeter, respectively. Mineralogical compositions of Fuller’s earth (containing unsieved earth, particle size range of150-180 µm and 45-63 µm) contains Smectite, Quartz, Calcite and Feldspar in varying proportion. Batch reactors(4000-mL polypropylene vessels; internal diameter - 0.16 m) was used as a test vessel for the study. Thus, the adsorption rate experiments was performed by using these Batch reactors(4000-mL polypropylene vessels; internal diameter - 0.16 m) as a test vessel. Test vessel contained three liters of chemical (C0 = 25 mg/dm3) and a fixed amount (100 mg/dm3) of Fullers earth.The mixing in each vessel was realized with a four-blade, flat stainless steel impeller of 0.075 m diameter with a blade height of 0.015 m. The particles of Fuller's earth (particularly, 150 to 180 >m particle size range) were fully suspended and uniformly mixed throughout the solution when the impeller speed was above 170 rpm. Therefore, an impeller speed of 200 rpm was adopted in the adsorption rate experiments. Three 400-mL samples were withdrawn from each vessel at three different contact times(tc) between adsorbate and adsorbent. These samples were filtered on Whatman GF/C filter by discharging the first 200-mL portion of filtered liquid. The filtrate was then analyzed for residual test chemical concentration usingtwo-phase titration method and/or disulphine blue colorimetric method, respectively.Successively, adsorption rate tests were also performed at different values of the solution pH, over the range of 5.0 to 9.0. The pH was adjusted and maintained at a constant value throughout the experiment by using either 0.1 M HC1 or 0.1 M NaOH. The adsorption isotherm experiments were conducted at a pH of 7.0 and 25 °C by using the conventional bottle-point technique. Varying amounts of Fuller's earth were added to 1000 mLpolypropylene bottles containing 700 mL of surfactant solution (C o = 25; 75 and 125 mg dm-3). After pH adjustment, the bottles were sealed and placed on a rotary tumbler which was immersed in a water-bath. A contact time of six days was selected to ensure the system equilibrium. This value oft ewas 35 to 80% higher than the time actually necessary for each system to come to equilibrium when the samples were agitated with a rotary tumbler. After shaking, each sample was filtered and analyzed for the equilibrium surfactant concentration in the solution (Ceq).Experiments on blank samples, i.e., without Fuller's earth, revealed no appreciable adsorption of surfactant on bottle walls. Residual concentration of test chemical was determined using the two-phase titration method, when the concentration was higher than 10 mg/dm3as cationic species. According to this method, 50 mL of sample was titrated with 10-3M sodium laurylsulphate solution by using 10 mL of hydroalcoholic dimidium bromide-disulphine blue solution as an indicator and 15 mL of chloroform as an extracting solvent. Lower test chemical concentrations were determined by using the disulphine blue colorimetric method. A 20-fold excess of disulphine blue reagent (1.3 × 10 .3 M aqueous solution), a working pH of 5.0 (acetate buffer) and three extractions with 10-mL portions of reagent-grade chloroform were necessary to ensure the complete extraction of the test chemical-disulphine blue compound from the aqueous solution.The absorbance of the chloroform extract was measured with a spectrophotometer at the wavelength of 628 nm against a chloroform reference. The amount of test chemical in the sample was determined by reference to a previously prepared calibration graph.The critical micelle concentration (CMC) of test chemical (surfactant) was evaluated at 25 °C from conductivity measurements on solutions with different test chemical concentration. After a contact time of 60 min, the percentage adsorption of the test chemical was determined to be 40.5% of the equilibrium adsorption (Co - Ceq), respectively. A slight increase in the adsorption was, however, observed for test chemical, particularly when the solution pH was increased from 5.0 to 7.0.Thus based on percentage adsorption of test chemical, it indicates that the test chemical hasa moderate sorption tosoil and sediment and therefore have slow migration potential to ground water.

 

On the basis of above overall results for test chemical (from experimental study report and peer reviewed journal), it can be concluded that the log Koc value of test chemical was determined to be 3.010, indicating that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.