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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Remarks:
Refined testing setup in relation to non-linearity of Freundlich isotherms for surfactants
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-10-04 to 2016-12-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Version / remarks:
Deviations from the Guideline
The number of soils which was used deviates from the recommendation in the guideline as three soils were used instead of the recommended five soils. The Freundlich isotherm was not determined and the adsorption / desorption behavior was investigated based on one test item concentration. Since the test item is poorly extractable from soil, the indirect method was used for evaluations even if the mass balance was < 90%. These deviations from the guideline were on request of the sponsor and are based on earlier adsorption / desorption studies with cationic surfactants.

Test item stability was verified by control samples. Samples were centrifuged < 3000 g because glass vessels had to be used. Higher centrifugation forces would have been destroyed these vials.

The deviations had no negative impact on the integrity and quality of the obtained data.

Deviations:
yes
Remarks:
see above at "Version / remarks"
Qualifier:
according to
Guideline:
other: Council Regulation (EC) No. 440/2008, Method C.18 (2008)
Principles of method if other than guideline:
The study procedures were based on OECD guideline 106 (OECD, 2000) and PART C: Methods for the determination of Ecotoxicity, C.18: “Adsorption/desorption using a batch equilibrium method“, Official Journal of the European Union, L 142, Volume 51, 31 May 2008.
The number of soils used in this test deviated from the recommendation in OECD guideline 106 in that three soils were used instead of the recommended five soils. This deviation was based on results of earlier adsorption/desorption tests with cationic surfactants. The partitioning to soil was not based on a Freundlich isotherm but was evaluated based on only one test concentration. The amine in the test substance will to a large extent be protonated under ambient conditions and will therefore interact with the negative surface of mineral particles or with negative charges of humic substances. The ionic interactions play a more important role than organic carbon content partitioning with organic matter. The log Koc was therefore considered as a poor predictor of the partitioning behaviour of the test substance in the environment, the determination of the Kd was also determined. The earlier results showed that using three soils, including at least one loamy sand and a clay soil, can give as much information as using the full number of soils. The earlier tests also revealed that only rarely linear adsorption isotherms were obtained for cationic surfactants and that extrapolation to lower concentrations based on these non-linear isotherms leads to unrealistic results (RAR primary fatty amines Oct. 2008). According to the Danish EPA 2004 a more reliable method of extrapolation to lower concentrations, was to use the data originating from the lowest measured concentration and to assume that the coefficient remained constant at lower concentrations. The test as described in this report was therefore performed using only one concentration which was as low as reasonably possible in relation to the detection limit.

The test was carried out in compliance with the OECD principles of Good Laboratory Practice (Annex 1).
GLP compliance:
yes (incl. certificate)
Type of method:
batch equilibrium method
Media:
soil
Radiolabelling:
no
Test temperature:
Nominal: 20 ± 2 °C
Analytical monitoring:
yes
Details on sampling:

Soil extraction (Tier 1):
After removal of the aqueous phase, the soil was dried in a drying cabinet to be removable from the test vessels. The soil was weighed into a solvent extractor cell. Glass beads were used as spacing material in the extractor cells. Then, the samples were extracted with methanol : 2-propanol (50 : 50). For parameters of the extraction method see below. Extracts were transferred quantitatively in a 50 mL measuring flask and filled up with 2-propanol. 0.01 M CaCl2 was used if dilution factor 2 was needed, dilution medium for further dilutions to calibration range.

Parameters of the extraction method:
Preheat: 1 min
Heat: 5 min
Static: 5 min
Flush: 50 % (v/v)
Purge: 90 sec
Cycles: 3
Pressure: 100 bar
Temperature:125 °C
Solvent: methanol : 2-propanol (50 : 50)

Soil extraction (“fresh spikes”):
o prove feasibility of extraction, conditioned soil was spiked with the test item and extracted directly after spiking. The soil was weighed into a solvent extractor cell and was spiked with the test item. Glass beads were used as spacing material in the extractor cells. Then, the samples were extracted with methanol : 2-propanol (50 : 50). For parameters of the extraction method see above. Extracts were transferred quantitatively in a 50 mL measuring flask and filled up with 2-propanol. 0.01 M CaCl2 was used for dilution factor 2, dilution medium for further dilutions to calibration range.


Samples for method validation:
Samples were prepared as described above. The aqueous phases were decanted and spiked with test item at 1 x LOQ level. Blank samples were prepared accordingly but without spiking with test item. Samples of 1 x LOQ level and blank samples were diluted with 2-propanol by factor 2 prior to analysis.

Matrix no.:
#1
Matrix type:
loamy sand
% Clay:
7.8
% Silt:
14
% Sand:
78.3
% Org. carbon:
1.6
pH:
6.7
CEC:
6 meq/100 g soil d.w.
Matrix no.:
#2
Matrix type:
other: Silty sand
% Clay:
9.8
% Silt:
29.3
% Sand:
61
% Org. carbon:
0.617
pH:
6.7
CEC:
5.4 meq/100 g soil d.w.
Matrix no.:
#3
Matrix type:
clay loam
% Clay:
27.5
% Silt:
44.2
% Sand:
28.3
% Org. carbon:
2.07
pH:
7.5
CEC:
26 meq/100 g soil d.w.
Details on matrix:
Relevant Characteristics of Test Matrices

Soils LUFA 2.2 LUFA 2.3 LUFA 2.4
Soil Type 1) Loamy sand Silty sand Clayey loam
pH (0.01 M CaCl2) 2) 6.7 6.7 7.5
Organic Carbon [%] 3) 1.60 0.617 2.07
Clay (<0.002 mm) [%] 3) 7.8 9.8 27.5
Silt (0.002-0.063 mm) [%] 3) 14.0 29.3 44.2
Sand (0.063-2 mm) [%] 3) 78.3 61.0 28.3
Cation Exchange Capacity [mval/100g] 3) 6.0 5.4 26
1) according to German DIN
2) data determined during the course of the study
3) determined at Agrolab Agrar und Umwelt GmbH (non-GLP)

Origin of soils LANDWIRTSCHAFTLICHE UNTERSUCHUNGS- UND FORSCHUNGSANSTALT LUFA SPEYER, Obere Langgasse 40, 67346 Speyer, Germany

Storage at test facility LUFA soils: Room temperature, in closed containers

Expiry date LUFA 2.2 (batch: F2.2 21016): 2021-03-21
LUFA 2.3 (batch: F2.3 1916): 2021-05-19
LUFA 2.4 (batch: F2.4 1016): 2021-06-13
Details on test conditions:
CaCl2-solution Deionised water was used to prepare the CaCl2-solution (0.01 M).

Soil / Solution ratio Tier 1: 1:50 and 1:100
Tier 2 and Tier 3: 1:100

Agitation By horizontal shaker. Frequency was adjusted to avoid sedimentation of soil particles during treatment.

Test temperature 20 +/- 2 °C


Test Procedure

Test vessels 120 mL disposable glass bottles with aluminium tops with PTFE seals

Concentration for adsorption / desorption experiments 3.0 mg/L test item; The concentration was found to be suitable for measurements above the limit of quantification of the experiments analytical method (10 µg/L test item) which was assigned with regard to the three analytes.


Stock solutions: A stock solution of 3 g/L of N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine in 50 mL 2-propanol was prepared. 0.1 volume-% (0.1 mL) of this stock solution, related to the volume of the aqueous phase in the soil suspensions, were used for spiking.

Dispersion treatment Agitation


Preparation:
Soil samples (conditioning)
The soils were weighed into the test vessels and an appropriate volume of 0.01 M CaCl2-solution was added. After agitation overnight (12 h minimum), the samples were used for adsorption experiments.

Samples for adsorption experiments:
The soil samples were conditioned as described above. 0.1 volume-% (0.1 mL) of the stock solutions, related to the volume of the aqueous phase in the soil suspensions was added in order to adjust the test concentrations. Afterwards, the samples were agitated.

Samples for desorption experiments:
Samples were prepared as described above and were agitated until adsorption was completed. Afterwards, the test vessels were centrifuged and the supernatant was replaced by fresh 0.01 M CaCl2-solution. Then the test vessels were agitated again to investigate the desorption behavior of the test item.

Samples for analysis:
The soil suspensions were centrifuged after agitation at 3000 rpm (2508 g) to separate the phases, followed by analysing the concentration of the analytes concentrations in aqueous phase by LC-MS/MS. For analysis of the soil, the aqueous phase was decanted and the soil was extracted, if feasible. During Tier 2 and Tier 3, test vessels were extracted / rinsed with organic solvent to determine test vessel adsorption. Extracts were also analysed by LC-MS/MS.

Replicates: All samples were prepared in duplicate.

Controls:
Test item control samples containing conditioned 0.01 M CaCl2-solution and the test item at 3.0 mg/L but without soil were prepared to proof stability of the test item in the test system.
For preparation, CaCl2-solution was conditioned as described above, followed by separation of the aqueous phase by centrifugation. Then the aqueous phase was fortified acc. to the concentrations used for the soil-containing samples and agitated as long as the sample with the longest agitation period.

Replicates: Duplicates

Blank:
Blank samples were prepared for all soils as described for the test item samples but without fortification with the test item. The samples were agitated as long as the samples with the longest agitation period.

Replicates: Duplicates (Tier 1), single (Tier 2 and Tier 3)

Sample Preparation:
Dilution medium 2-Propanol : 0.01 M CaCl2 (50:50) conditioned with soil

Standards:
A stock solution of 3 g/L of N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine in 50 mL 2-propanol was prepared. The solution was diluted to 7 calibration standards in the range of 2 to 100 µg/L with dilution medium.

Aqueous phase:
Suspensions (test item replicates and blanks) were centrifuged at 3000 rpm for 5 min. An aliquot of each aqueous sample was stabilized by dilution with 2-propanol (factor 2). Samples were diluted to calibration range with dilution medium, if necessary.

Test vessel adsorption:
After sampling of the aqueous phase, the test vessels were emptied and rinsed with 0.01 M CaCl2. 2-Propanol was used for extraction of the test item from the test vessel. Therefore, the vessel was shaken by hand for 1 min, ultrasound was used for 5 min and the vessel was shaken 20 min on a shaker. 0.01 M CaCl2 was used if dilution factor 2 was needed, dilution medium for further dilutions to calibration range, if necessary.
Key result
Sample No.:
#1
Type:
Kd
Remarks:
Weighted mean of three main constituents
Value:
482 L/kg
pH:
6.7
Temp.:
20 °C
Matrix:
LUFA 2.2 Loamy sand
% Org. carbon:
1.6
Remarks on result:
other: Sorption of cationic surfactant should not be normalized to the organic carbon content
Key result
Sample No.:
#2
Type:
Kd
Remarks:
Weighted mean of three main constituents
Value:
1 506 L/kg
pH:
6.7
Temp.:
20 °C
Matrix:
LUFA 2.3 Silty Sand
% Org. carbon:
0.617
Remarks on result:
other: Sorption of cationic surfactant should not be normalized to the organic carbon content
Key result
Sample No.:
#3
Type:
Kd
Remarks:
Weighted mean of three main constituents
Value:
3 302 L/kg
pH:
7.5
Temp.:
20 °C
Matrix:
LUFA 2.4 Clay Loam
% Org. carbon:
2.07
Remarks on result:
other: Sorption of cationic surfactant should not be normalized to the organic carbon content
Adsorption and desorption constants:
Summarized Endpoints for N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine and the Active Ingredients
Mobility according to McCall et al. (1980): KOC 0 – 50 very high, KOC 50 – 150 high, KOC 150 – 500 medium, KOC 500 – 2000 low, KOC 2000 – 5000 slight, KOC > 5000 immobile
caq (eq)
[µg/L] Kd
[mL/g] KOC
[mL/g] Kdes
[mL/g] Mobility according to McCall et al.
Soil/Solution Ratio 1:100
C16:0 Compound
LUFA 2.2 92.1 605 37841 2051 immobile
LUFA 2.3 29.9 1938 314153 14349 immobile
LUFA 2.4 17.9 3545 171247 30117 immobile
C18:0 Compound
LUFA 2.2 137 364 22759 1267 immobile
LUFA 2.3 38.5 1459 236537 14262 immobile
LUFA 2.4 14.3 4304 207903 18588 immobile
C18:1 Compound
LUFA 2.2 132 477 29795 1756 immobile
LUFA 2.3 58.8 1121 181740 13081 immobile
LUFA 2.4 35.8 2058 99406 27074 immobile
N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine
LUFA 2.2 542 482 30131 1692 immobile
LUFA 2.3 188 1506 244143 13897 immobile
LUFA 2.4 99.3 3302 159519 25259 immobile
caq (eq) = concentration in the aqueous phase at adsorption equilibrium; value was calculated for
N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine from measured
concentrations of the active ingredients and taking the respective contents into account
Recovery of test material:
Different solvents have been tested for soil extraction during method development (non-GLP).
The best result was obtained by using accelerated solvent extractor. During Tier 1, samples were extracted after 24 h. Recovery rates of 30% to 44% of the nominal concentration for the analytes from LUFA 2.2 and 1% to 10% from LUFA 2.4 were obtained. In addition, freshly spiked samples were extracted by the same method, to prove feasibility of extraction. Recovery rates of 16% to 19% of the nominal concentration for the analytes from LUFA 2.2 and 54% to 56% from LUFA 2.4 were obtained. Since the test item is poorly extractable from soil, the indirect method was used for evaluations even if the mass balance was < 90%.
Concentration of test substance at end of adsorption equilibration period:
caq (eq)
[µg/L]
Soil/Solution Ratio 1:100
C16:0 Compound
LUFA 2.2 92.1
LUFA 2.3 29.9
LUFA 2.4 17.9
C18:0 Compound
LUFA 2.2 137
LUFA 2.3 38.5
LUFA 2.4 14.3
C18:1 Compound
LUFA 2.2 132
LUFA 2.3 58.8
LUFA 2.4 35.8
N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine
LUFA 2.2 542
LUFA 2.3 188
LUFA 2.4 99.3
Transformation products:
no
Remarks:
Test Item Stability The test item stability was confirmed by measurement of two test item control replicates during each adsorption experiment. The good recovery of the control samples verified the test item stability throughout the study.
Details on results (Batch equilibrium method):
See any other information on results incl tables

Temperature

The temperature was in the range of 20 ± 2 °C during the course of the study.

Soil Dry Weights

The soil dry weight of each soil type used was determined.

 

Soil Dry Weights

Mean values (n = 3)

 

Soil

LUFA 2.2

LUFA 2.3

LUFA 2.4

soil dry weight [%]

92.7

97.5

93.8

pH Values

The pH values of the aqueous media of the test systems were measured before and after equilibration with the corresponding soils, after addition of the test item and after desorption. Results are shown in the following table.

 pH Values of the Aqueous Media

Soil / Solution Ratio 1:100

 

Soils

 

LUFA 2.2

LUFA 2.3

LUFA 2.4

0.01 M CaCl2

6.4

6.6

6.6

after soil contact

6.7

6.7

7.5

after addition of the test item

6.7

7.0

7.4

after desorption

7.1

6.8

7.8

 

 Tier 1–Adsorption / Desorption

LUFA 2.2 and LUFA 2.4 were used for preliminary investigations on the adsorption behavior of the test item with soil / solution ratios of 1:50 and 1:100 at a concentration of 3.0 mg/L. An adsorption of ≥ 86% was determined for the three analytes in both soils. The equilibrium of the adsorption was reached after 24 h. Test item control samples (samples without soil) showed good recoveries but showed that test vessel adsorption had to be taken into account for calculations during adsorption experiments. Thus, test item stability was proven. Concentrations and sampling points for Tier 2 have been assigned based on results in the following tables. Analytical results are shown in part 12 of the attached full study report.

Tier 1:LUFA 2.2 – Soil / Solution Ratios 1:100 and 1:50

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

4

92

87

91

24

95

91

93

1:100

3.0

4

92

89

92

24

95

94

93

1)                     = measured value for aqueous phase below lowest calibration level

 

Tier 1:LUFA 2.4 – Soil / Solution Ratios 1:100 and 1:50

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

4

98

99

97

24

95

96

93

1:100

3.0

4

97

97

96

24

92

94

86


 

Tier 1– Test Vessel Adsorption

The test item adsorption to the test vessel was determined in Tier 1 for the samples with the longest agitation period. Test vessel adsorption was significantly higher in test item control samples (samples without soil) than in soil-containing replicates. Since significant adsorption was determined for test item control samples, test vessels had to be extracted during Tier 2 and the determined test vessel adsorption had to be taken into account for the respective calculations. Details of the measurements are shown in part 12 of the attached full study report.

Tier 1:LUFA 2.2 – Test Vessel Adsorption

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

24

0.6

0.9

0.9

1:100

3.0

24

0.6

1.1

1.5

 

Tier 1:LUFA 2.4 – Test Vessel Adsorption

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

24

0.2

0.1

0.3

1:100

3.0

24

0.2

0.2

0.3

 

Tier 1:LUFA 2.2 – Test Vessel Adsorption – Control Samples

0.01 M CaCl2was conditioned with LUFA 2.2

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

24

8

14

11

1:100

3.0

24

8

16

12

 


 

Tier 1:LUFA 2.4 – Test Vessel Adsorption – Control Samples

0.01 M CaCl2was conditioned with LUFA 2.4

Soil / Solution Ratio

Applied concentration, test item [mg/L]

Sampling point [h]

Adsorption
C16:0 Compound [%]

Adsorption
C18:0 Compound [%]

Adsorption
C18:1 Compound [%]

1:50

3.0

24

17

21

20

1:100

3.0

24

25

29

28

 

Tier 1– Extraction from Soil / Mass Balance

Different solvents have been tested for soil extraction during method development (non-GLP). The best result was obtained by using accelerated solvent extractor and the method described above. During Tier 1, samples were extracted after 24 h. Recovery rates of 30% to 44% of the nominal concentration for the analytes from LUFA 2.2 and 1% to 10% from LUFA 2.4 were obtained. In addition, freshly spiked samples were extracted by the same method, to prove feasibility of extraction. Recovery rates of 16% to 19% of the nominal concentration for the analytes from LUFA 2.2 and 54% to 56% from LUFA 2.4 were obtained. Since the test item is poorly extractable from soil, the indirect method was used for evaluations even if the mass balance was < 90%.

 Tier 2 – Adsorption Kinetics

The determination for adsorption kinetics was performed with a nominal test item concentration of 3.0 mg/L. A soil / solution ratio of 1:100 was used and concentrations of the test item were measured in aqueous phase and in extracts of the test vessels at defined sampling points. The following tables show the percentage of adsorption at equilibrium, the time needed to reach the adsorption equilibrium as well as the obtained distribution coefficients Kd and their corresponding organic carbon normalized distribution coefficients KOC. The test item shows high adsorption within a few hours to all tested soils. Analytical data are shown in part12 of the attached full study report.

 

Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients Kd, KOC for C16:0 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.:63.0 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

madsaq(eq) [µg]

madss(eq) [µg]

Kd[mL/g]

%OC

KOC[mL/g]

Adsorption [%]

LUFA 2.2

24

0.927

9.53

53.5

605

1.60

37841

85

LUFA 2.3

24

0.975

3.17

59.8

1938

0.617

314153

95

LUFA 2.4

24

0.938

1.84

61.2

3545

2.07

171247

97

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

madsaq        =amount of a.i. in the aqueous phase at equilibrium

madss          =amount of a.i. in the soil at equilibrium

%OC         =percentage of organic carbon content in the soil

 


 Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients Kd, KOC for C18:0 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.:62.7 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

madsaq(eq) [µg]

madss(eq) [µg]

Kd[mL/g]

%OC

KOC[mL/g]

Adsorption [%]

LUFA 2.2

24

0.927

14.3

48.4

364

1.60

22759

77

LUFA 2.3

24

0.975

4.12

58.6

1459

0.617

236537

93

LUFA 2.4

24

0.938

1.52

61.2

4304

2.07

207903

98

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

madsaq        =amount of a.i. in the aqueous phase at equilibrium

madss          =amount of a.i. in the soil at equilibrium

%OC         =percentage of organic carbon content in the soil

Equilibrium Time, Measured Amounts in Aqueous Phase and Soil Extracts, Percent of Adsorption and Distribution Coefficients Kd, KOC for C18:1 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.:74.4 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

madsaq(eq) [µg]

madss(eq) [µg]

Kd[mL/g]

%OC

KOC[mL/g]

Adsorption [%]

LUFA 2.2

24

0.927

13.7

60.7

477

1.60

29795

82

LUFA 2.3

24

0.975

6.23

68.2

1121

0.617

181740

92

LUFA 2.4

24

0.938

3.66

70.7

2058

2.07

99406

95

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

madsaq        =amount of a.i. in the aqueous phase at equilibrium

madss          =amount of a.i. in the soil at equilibrium

%OC         =percentage of organic carbon content in the soil

 


Tier 3 – Desorption Kinetics

The desorption behavior of the test item was determined after 24 h adsorption with the desorption equilibrium after 24 h. The following tables show the desorption coefficient Kdes. Since the desorption coefficient is higher than the adsorption coefficient Kd, the test item adsorption is assumed to be not completely reversible. Nevertheless, it is noteworthy that by measuring the concentrations of the analytes in the aqueous phase, desorption from soil and desorption from the test vessel are not distinguishable.Details of the measurements are shown in part12 of the attached full study report.

 

Percent of Desorption and Desorption Coefficient Kdes for C16:0 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.:63.0 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

mdesaq(eq) [µg]

madss(eq) [µg]

Kdes[mL/g]

Desorption [%]

LUFA 2.2

24

0.927

2.91

58.2

2051

5

LUFA 2.3

24

0.975

0.426

60.0

14349

0.7

LUFA 2.4

24

0.928

0.214

60.5

30117

0.4

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

mdesaq        =amount a.i. measured in the aqueous phase after desorption step

(entrained water taken into account)

madss          =amount of a.i. adsorbed to soil at equilibrium


 

Percent of Desorption and Desorption Coefficient Kdes for C18:0 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.: 62.7 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

mdesaq(eq) [µg]

madss(eq) [µg]

Kdes[mL/g]

Desorption [%]

LUFA 2.2

24

0.927

4.36

55.6

1267

8

LUFA 2.3

24

0.975

0.421

58.9

14262

0.7

LUFA 2.4

24

0.928

0.347

60.8

18588

0.6

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

mdesaq        =amount a.i. measured in the aqueous phase after desorption step

(entrained water taken into account)

madss          =amount of a.i. adsorbed to soil at equilibrium

Percent of Desorption and Desorption Coefficient Kdes for C18:1 Compound

Applied concentration, test item:          3.0 mg/L

Applied amount, test item:                     300 µg

Applied amount, a.i.:74.4 µg

n = 2; soil / solution ratio: 1:100

Vaq= 100 mL

Soil Type

teq[h]

msoil[g]

mdesaq(eq) [µg]

madss(eq) [µg]

Kdes[mL/g]

Desorption [%]

LUFA 2.2

24

0.927

3.93

67.9

1756

6

LUFA 2.3

24

0.975

0.533

68.5

13081

0.8

LUFA 2.4

24

0.928

0.272

69.4

27074

0.4

Vaq            =used volume of aqueous phase

teq              =time to reach equilibrium

msoil          =used amount of soil (dry weight)

mdesaq        =amount a.i. measured in the aqueous phase after desorption step

(entrained water taken into account)

madss          =amount of a.i. adsorbed to soil at equilibrium

 

 Control Samples

The test item stability was confirmed by measurement of two control replicates during each adsorption experiment. The following table shows the recovery rate for control samples. The recovery is related to the nominal applied concentration and the adsorption to the test vessel is taken into account at the end of the experiment.

 

Recovery Rates [%] of the Control Samples

Sampling Point

LUFA 2.2

LUFA 2.3

LUFA 2.4

Tier 1– Soil Solution Ratio 1:50

C16:0 Compound

0h

100

n.d.

100

24h

106

n.d.

104

C18:0 Compound

0h

101

n.d.

104

24h

103

n.d.

105

C18:1 Compound

0h

100

n.d.

94

24h

105

n.d.

105

Tier 1– Soil Solution Ratio 1:100

C16:0 Compound

0h

111

n.d.

95

24h

102

n.d.

94

C18:0 Compound

0h

114

n.d.

102

24h

96

n.d.

94

C18:1 Compound

0h

106

n.d.

98

24h

99

n.d.

95

Tier 2

C16:0 Compound

0h

99

95

99

24h

103

108

83

C18:0 Compound

0h

103

118

86

24h

100

84

88

C18:1 Compound

0h

102

106

94

24h

103

101

84

n.d.  = not determined

 

Validity criteria fulfilled:
yes
Conclusions:
Study performed according OECD and EEC guideline under GLP conditions. Test substance is a UVCB and the partitioning is therefore measured for the three main constituents. Test is performed without 14C material which means that obtaining a mass balance with this type of substances is very difficult. The substance was found to be stable during the test therefore the indirect method was used to determine the partitioning constants.


Executive summary:

The adsorption / desorption behavior of the test item N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine (batch no.211401A Morris) was investigated in three different soils accordingto OECD guideline 106 and EC C.18 from 2016-10-04 to 2016-12-02 at Noack Laboratorien GmbH, 31157 Sarstedt, Germany. Distribution coefficients Kd and organic carbon normalized distribution coefficients KOC were determined with a single concentration. In addition, the desorption behavior / reversibility of the adsorption from the soils was investigated.

 

RelevantCharacteristics of Test Matrices

 

Soils

 

LUFA 2.2

LUFA 2.3

LUFA 2.4

Soil Type1)

Loamy sand

Silty sand

Clayey loam

pH (0.01 M CaCl2)2)

6.7

6.7

7.5

Organic Carbon [%]3)

1.60

0.617

2.07

Clay (<0.002 mm) [%]3)

7.8

9.8

27.5

Silt (0.002-0.063 mm) [%]3)

14.0

29.3

44.2

Sand (0.063-2 mm) [%]3)

78.3

61.0

28.3

Cation Exchange Capacity [mval/100g]3)

6.0

5.4

26

1)according to German DIN

2) data determined during the course of the study

3)determined at Agrolab Agrar und Umwelt GmbH (non-GLP) for soils used during Tier 2 and Tier 3

 

Based on results of preliminary investigations during Tier 1, a soil / solution ratio of 1:100 was used for adsorption experiments. Experiments for adsorption and desorption kinetics were conducted with a nominal test item concentration of 3.00 mg/L. Three active ingredients N-(C16, alkyl) trimethylpropane-1,3-diamine, N-(C18, alkyl) trimethylpropane-1,3-diamine and N-(C18 unsaturated, alkyl) trimethylpropane-1,3-diamine have been analysed by LC-MS/MS. Data are given for each analyte in this report. Detailed analytical data are shown in part12 of the attached full study report.

The table below shows obtained distribution coefficients Kd and their corresponding organic carbon normalized distribution coefficients KOC. Furthermore, the mobility of the test item in the investigated matrices was classified according to McCall et al (1980). Additionally, the desorption coefficient Kdes is presented in the summarizing table.


Summarized Endpoints for N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine and the Active Ingredients

Mobility according to McCall et al. (1980): KOC 0 – 50 very high, KOC 50 – 150 high, KOC150 – 500 medium, KOC 500 – 2000 low, KOC 2000 – 5000 slight, KOC > 5000 immobile

 

Kd [mL/g]

KOC [mL/g]

Kdes [mL/g]

Mobility according to McCall et al.

Soil/Solution Ratio

1:100

C16:0 Compound

LUFA 2.2

577

36089

2051

immobile

LUFA 2.3

1938

314153

14349

immobile

LUFA 2.4

3545

171247

30117

immobile

C18:0 Compound

LUFA 2.2

347

21705

1267

immobile

LUFA 2.3

1459

236537

14262

immobile

LUFA 2.4

4304

207903

18588

immobile

C18:1 Compound

LUFA 2.2

455

28415

1756

immobile

LUFA 2.3

1121

181740

13081

immobile

LUFA 2.4

2058

99406

27074

immobile

N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine

LUFA 2.2

482

28736

1692

immobile

LUFA 2.3

1506

181740

13897

immobile

LUFA 2.4

3302

99406

25259

immobile

 

 

The test item N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine adsorbs strongly to all tested soils with Kocvalues > 5000. The strongest adsorption was determined for LUFA 2.3. The desorption was determined to be not completely reversible.
The Freundlich isotherm was not determined and the adsorption / desorption behavior was investigated based on one test item concentration. Since the test item is poorly extractable from soil, the indirect method was used for evaluations even if the mass balance was < 90%. These deviations from the guideline were on request of the sponsor and are based on earlier adsorption / desorption studies with cationic surfactants.

Description of key information

Non-linear sorption is normally observed in standard sorption desorption tests with cationic surfactants. Extrapolation based on these non-linear Freundlich isotherms to environmental representative concentration gives frequently unrealistic predictions. Danish EPA pesticides Research report nr 63 (RSS included) comes to the conclusion that for these substances the most reliable method of extrapolation is to use the data originating from the lowest aqueous measured concentrations letting the intercept equal zero. Using this approach the observed Kd values for N-C16-18-alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3-diamine for loamy sand, silty sand and clay loam are resp. 482, 1506 and 3302 L/kg. The mean value of 1763 L/kg is used for risk assessment. Normalisation of the adsorption coefficients based on the organic carbon content of the sorbent is not justified considering the properties of the test substance where sorption will take place for a large part via cation exchange and will due to this lead to erroneous predictions.

Key value for chemical safety assessment

Other adsorption coefficients

Type:
log Kp (solids-water in soil)
Value in L/kg:
3.246
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in sediment)
Value in L/kg:
3.246
at the temperature of:
20 °C

Other adsorption coefficients

Type:
log Kp (solids-water in suspended matter)
Value in L/kg:
3.547
at the temperature of:
20 °C

Additional information