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Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
unsuitable test system
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
no
Type of method:
batch equilibrium method
Media:
soil
Test material information:
Composition 1
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material:629582
-Purity: 98.3%
- Expiration date of the lot/batch:June 9, 2017

Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
A Tier I study was conducted in 15-mL polypropylene (PP) centrifuge tubes to evaluate: 1) the performance of the analytical method(s) for sensitive and accurate quantitation of the MTDID 15670 anion and cation components in the test matrices and results verified the appropriate test concentration to use and showed that adsorption to test vessels did not occur; 2) A preliminary adsorption test using 2 control soils (one clay and one loam) and results were used to determine the appropriate soil-solution ratio for Tier II adsorption kinetic testing; 3) organic solvents for efficient extractive recovery of adsorbed MTDID 15670 from
soil for mass balance evaluations. Once optimal conditions were determined, the Tier II testing was performed to determine adsorption kinetics at one concentration with five soils for determining adsorption coefficients (Kd) and desorption characteristics of MTDID 15670.

Tier II Adsorption study: Only the cation was evaluated in Tier II adsorption testing. The anion component was not evaluated since Tier I testing showed it did not adsorb to soil at the highest soil-solution ratio evaluated (1:5). Five soils were selected to test the adsorption/desorption of MTDID 15670 at a soil-solution ratio (1:100, w/v). Tier II testing was performed at an aqueous phase concentration of 2.5 μg/mL MTDID 15670 (equivalent to 1.94 μg/mL cation and in a 10-mL sample volume) and evaluated at a soil-solution ratio of 1:100 (w/v). Specifically, nominal 0.1 g of soil samples with 9.90 mL 0.01M CaCl2 solution, soil-solution (1:100), were prepared, in duplicate, in 15 mL centrifuge tube. The adsorption procedures were same as the tier I study. The adsorption solution were collected and analyzed by LC/MS/MS for cation concentrations only.

Tier II Desorption study: After careful removal of the adsorption solution from the soil samples, 10.0 mL of aqueous 0.01M CaCl2 was added to desorb the cation from soils in each centrifuge tube. These samples were placed on the orbital shaker set at 250 RPM for 1 hour and then centrifuged at 5000 RPM for 15 min. The desorption solution were collected and diluted 2-fold by adding 500 μL of the desorption solution and 500 μL of the diluent III for the cation analysis.

Tier II Soil extraction: The soil samples were further extracted using acetonitrile after the desorption solution was carefully removed as much as possible without removing any of solid layer. The soil samples were extracted 3 times. Firstly, 4 mL of acetonitrile was added in all the samples. The samples were placed on the orbital shaker set at 250 RPM for 20 min and centrifuged at 5000 RPM for 15 min to make the supernatant clear. The supernatant was transferred to another centrifuge tube. Then 3 mL of acetonitrile was added the corresponding samples for the second and third extractions. The samples were placed on an orbital shaker set at 250 RPM for 20 min and centrifuged at 5000 RPM for 15 min to make the supernatant clear. The supernatant of 3 time extraction was combined. The total extract volume was 10 mL for each sample. The soil sample extract was diluted 10-fold by adding 100 μL of the sample extract and 900 μL of the diluent I (soil matrix solution with 0.2% acetic acid and 100 ng/mL of PhI-urea) for cation analysis.
Matrix no.:
#1
Matrix type:
clay
% Clay:
62
% Org. carbon:
2.6
pH:
7.2
CEC:
54.5 meq/100 g soil d.w.
Matrix no.:
#2
Matrix type:
silt loam
% Org. carbon:
4.4
Matrix no.:
#3
Matrix type:
loam
% Clay:
11
% Org. carbon:
4.9
pH:
7.4
CEC:
23.9 meq/100 g soil d.w.
Matrix no.:
#4
Matrix type:
sandy clay loam
% Clay:
18
% Org. carbon:
2
pH:
6.4
CEC:
16.4 meq/100 g soil d.w.
Matrix no.:
#5
Matrix type:
sand
% Clay:
2
% Org. carbon:
1.1
pH:
5.3
CEC:
7.2 meq/100 g soil d.w.
Details on test conditions:
TEST SYSTEM
- Type, size and further details on reaction vessel: 15 mL centrifuge tubes
- Water filtered (i.e. yes/no; type of size of filter used, if any): No
- Amount of soil/sediment/sludge and water per treatment (if simulation test) :0.1 g of soil samples with 9.90 mL 0.01M CaCl2 solution (tier II study)
- Soil/sediment/sludge-water ratio (if simulation test): 1:100 (tier II study)
- Number of reaction vessels/concentration: Two
- Measuring equipment:HPLC/MS/MS
- Method of preparation of test solution:
Diluent I: For cation calibration standards and LCSs, the diluent was the soil matrix solution with 0.2% acetic acid and 100 ng/mL of PhI-urea (IS);
diluent II: For anion calibration standards and LCSs, the diluent was the soil matrix solution with 100 ng/mL of PFBS (IS);
diluent III: For the cation analysis in soil samples, the diluent was the soil matrix solution with 0.4% acetic acid and 200 ng/mL of PhI-urea (IS);
diluent IV: For the anion analysis in soil samples, the diluent was the soil matrix solution with 200 ng/mL of PFBS.
Key result
Type:
Kd
Value:
>= 225 - <= 20 300 other: cm^3/g
% Org. carbon:
>= 1.1 - <= 4.9
Remarks on result:
other:
Remarks:
soil pH ranged from 5.3 to 7.4
Transformation products:
no
Details on results (Batch equilibrium method):
Tier I preliminary adsorption test: A tier I preliminary adsorption test of MTDID 15670 was conducted using two control soils, Clay (TCR-840) and Loam (TCR-843), and was performed at different soil-solution ratios ranging from 1:5 to 1:100. MTDID 15670 cation at 1.94 μg/mL aqueous phase concentration was > 98% adsorbed to clay (TCR-840) and loam (TCR-843) soils at all soil-solution ratios (ranging from 1:5 to 1:100) tested. The adsorption reached equilibrium within 20 minutes (Results not shown). MTDID 15670 anion did not adsorb to soils at any soil-solution ratio and was not further tested. A Tier I Solvent extraction of cation adsorbed to loam (TCR-843) soil was shown to be best with acetonitrile (~80% recovery), and less effective (<60%) for methanol, acetone or DMSO. Detailed tier I results not shown. 

Tier II screening kinetic adsorption test: The Tier II screening kinetic testing was conducted with five soils at one concentration (2.5 μg/mL MTDID 15670) and one soil:solution ratio (1:100). After at least 12 hour adsorption phase, the cation concentration in the aqueous phase were measured and the % cation in the aqueous phase ranged from 0.481% in clay (TCR-840) to 30.6% for sand (TCR-835) (Table 1). The Kd values for the cation were calculated as the ratio between the concentration of the cation adsorbed to the soil (mg/g) and the concentration of the cation in the aqueous solution (mg/mL), assuming the remainder were adsorbed to soil. The cation had appreciably large Kd values, ranging from 225 to 20300 cm3/g in the evaluated soil systems. The highest Kd was 20300 cm3/g in the clay (TCR-840) with the highest cation exchange capacity (CEC) of 54.5 meq/100g. The lowest Kd value was 225 cm3/g in the sand (TCR-835), which had the lowest CEC of 7.2 meq/100g (Table 2). Other Kd values were 1597 cm3/g, 2946 cm3/g and 7020 cm3/g for the sandy clay loam (TCR- 661), loam (TCR-843) and silt loam (TCR-678), respectively (Table 2). The correlation between soil Kd values and the soil cation exchange capacity (CEC) showed a linear log-log relationship with good correlation (R2=0.9976) (Fig. 1).

The average cation percentages resulting from a desorption evaluation using aqueous 0.01 M CaCl2 showed low desorption of < 0.400% for clay, <0.400% for silt loam, 0.487% for loam, 1.11% for sandy clay loam, and 0.523% for sand, respectively (detailed results not shown).

The soil adsorbed cation were extracted using acetonitrile solvent. The average extraction recoveries were 53.1% (RPD 3.9%) for clay, 56.2% (RPD 3.7%) for silt loam, 65.5% (RPD 0%) for loam, 17.7% (RPD 4.9%) for sandy clay loam, and 5.98% (RPD 8.6%) for sand.

The total mass balance of the cation varied for the different soils. The cation had the highest mass recovery of 69.2% (RPD 0.74%) in loam soil. The lowest mass recovery for the cation was 24.6% (RPD 1.6%) for sandy clay loam. The total mass recoveries for the cation were 57.6% (RPD 3.2%), 37.1% (RPD 17%) and 53.6% (RPD 3.8%) for silt loam, sand, and clay, respectively.

MTDID 15670 was later found to be hydrolytical unstable. The poor mass balance may be due to the instability of the cation in the test system or irreversible adsorption to the soils.

Table 1:  Tier II Cation adsorption results*

 Soil Matrix

rep

Cation conc. (ng/mL) in aqueous phase

% of Cation in aqueous phase

Average % Cation in aqueous phase

RPD (%)

Average Cation adsorbed to soil (%)

#1 (Clay, TCR-840)

1

9.57

0.493

0.481

5

99.5

2

9.08

0.468

 

 

 

#2 (Silt loam, TCR-678)

1

25.1

1.29

1.39

14

98.6

2

28.8

1.48

 

 

 

#3 (Loam, TCR-843)

1

67.2

3.46

3.25

13

96.8

2

59

3.04

 

 

 

#4 (Sandy clay loam, TCR-661)

1

106

5.46

5.77

11

94.2

2

118

6.08

 

 

 

#5 (Sand, TCR-835)

1

648

33.4

30.6

19

69.4

2

538

27.7

 

 

 

* soil: solution ratio = 1:100, Spiked cation concentration = 1940 ng/mL

Table 2. Tier II  MTDID 15670 Cation Kd results

 Soil matrix

rep

Total Cation (ug) in solution

Total cation (ug) in soil*

Kd (cm3/g)

average Kd

(cm3/g)

RPD%

Soil CEC (meg/100g)

#1

(Clay, TCR-840)

1

0.0957

19.3

19854

20300

4

54.5

2

0.0908

19.3

20747

 

 

 

#2

(Silt loam, TCR-678)

1

0.251

19.1

7502

7020

14

ND

2

0.288

19.1

6538

 

 

 

#3

(Loam, TCR-843)

1

0.672

18.7

2746

2946

14

23.9

2

0.590

18.8

3147

 

 

 

#4

(Sandy clay loam, TCR-661)

1

1.06

18.3

1690

1597

12

16.4

2

1.2

18.2

1503

 

 

 

#5

(Sand, TCR-835)

1

6.48

12.9

195

225

27

7.2

2

5.38

14.0

254

 

 

 

 

Conclusions:
The test system was unsuitbale due to rapid hydrolysis of MTDID 15670 cation. MTDID 15670 anion did not adsorb to soils.
Executive summary:

The soil adsorption/desorption character of MTDID 15670 was determined in a Tier I preliminary adsorption test and a Tier II screening adsorption kinetic test, in accordance with OECD 106 “Adsorption-Desorption Using a Batch Equilibrium Method”.

In the Tier I preliminary adsorption test conducted at 2.5 μg/mL MTDID 15670 and at soil-solution ratios ranging from 1:5 to 1:100 using two control soils (clay and loam), MTDID 15670 cation was > 98% removed from the aqueous phase within 20 minutes.  The anion did not adsorb to soils at any soil-solution ratio. Therefore, the anion Kd values were not determined.

The Tier II screening kinetic testing was conducted with five soils at one concentration (2.5 μg/mL MTDID 15670) and one soil:solution ratio (1:100). After adsorption phase, the % cation in the aqueous phase ranged from 0.481% (clay) to 30.6% (sand), the remainder were assumed to be adsorbed to soil. The Kd values for the cation were calculated as the ratio between the concentration of the cation adsorbed to the soil (mg/g) and the concentration of the cation in the aqueous solution (mg/mL). MTDID 15670 cation had Kd values of 225 cm3/g for sand, 1597 cm3/g for sand clay loam, 2946 cm3/g for laom, 7020 cm3/g for silt loam, and 20300 cm3/g for clay. In addition, the correlation between soil Kd values and the soil cation exchange capacity (CEC) showed a linear log-log relationship with correlation coefficient of R2=0.9976.

A desorption evaluation using aqueous 0.01 M CaCl2 showed low desorption for cation with average cation percentages of < 0.400% for clay, <0.400% for silt loam, 0.487% for loam, 1.11% for sandy clay loam,  and 0.523% for sand, respectively.

The soil was also extracted with acetonitrile solvent after desorption phase to obtain total mass balance. The average extraction recoveries ranged from 5.98% to 65.5%. The total mass recoveries of the cation were 69.2% (RPD 0.74%) for loam soil, 57.6% (RPD 3.2%) for silt loam,  53.6% (RPD 3.8%) for clay,  37.1% (RPD 17%)  for sand, and 24.6% (RPD 1.6%) for sandy clay loam.

MTDID 15670 cation was later found to be hydrolytical unstable. The poor mass balance may be due to the instability of the cation in the test system or irreversible adsorption to the soils. Since there were no mechanism to differentiate the adsorption from hydrolysis, the measured Kd values are considered invalid and this study is considered a disregarded study.

Endpoint:
adsorption / desorption: screening
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: REACH Technical Guidance Document on Risk Assessment
GLP compliance:
no
Remarks:
QSAR
Test material information:
Composition 1
Specific details on test material used for the study:
MTDID 15670 hydrolysis product: Dodecyl ethyl sulfide
EC# N/A
CAS# N/A

Radiolabelling:
no
Key result
Type:
Koc
Value:
410 000 dimensionless

Soil-water partition coefficient (Koc and log Koc ) can be calculated using the equation from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, Table 4, page 26:

for predominantly hydrophobics: Log Koc (unitless) = 0.81 logKow + 0.10,

Dodecyl ethyl sulfide has an estimated log Kow of 6.81 at 25 °C.

Based on the equation, the calculated log Koc (unitless) was 5.62, the Koc was 4.1E+05 (unitless).

Validity criteria fulfilled:
yes
Conclusions:
Dodecyl ethyl sulfide is a hydrolysis product of MTDID 15670. The calculated Koc for dodecyl ethyl sulfide is 4.1E+05 using the Technical Guidance equation.
Executive summary:

Dodecyl ethyl sulfide is a hydrolysis product of MTDID 15670. Soil-water partition coefficient (Koc and log Koc ) can be calculated using the equation from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, Table 4, page 26: for predominantly hydrophobics: Log Koc (unitless) = 0.81 logKow + 0.10, Dodecyl ethyl sulfide has an estimated log Kow of 6.81 at 25 °C. Based on the equation, the calculated log Koc (unitless) was 5.62, the Koc was 4.1E+05 (unitless).

Endpoint:
adsorption / desorption: screening
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Reference:
Composition 0
Qualifier:
according to
Guideline:
other: REACH Technical Guidance Document on Risk Assessment
GLP compliance:
no
Remarks:
QSAR
Test material information:
Composition 1
Radiolabelling:
no
Key result
Type:
Koc
Value:
22 dimensionless

Soil-water partition coefficient (Koc and log Koc ) can be calculated using the equation from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, Table 4, page 26:

for Nonhydrophobics: Log Koc (unitless) = 0.52 logKow + 1.02,

Crotononitrile has an estimated log Kow of 0.62 at 25 °C.

Based on the equation, the calculated log Koc (unitless) was 1.34, the Koc was 22 (unitless).

Validity criteria fulfilled:
yes
Conclusions:
Crotononitrile is a hydrolysis product of MTDID 15670. The calculated Koc for crotononitrile is 22 using the Technical Guidance equation.
Executive summary:

Crotononitrile is a hydrolysis product of MTDID 15670. Soil-water partition coefficient (Koc and log Koc ) can be calculated using the equation from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, Table 4, page 26: for Nonhydrophobics: Log Koc (unitless) = 0.52 logKow + 1.02.

Crotononitrile has an estimated log Kow of 0.62 at 25 °C. Based on the equation, the calculated log Koc (unitless) was 1.34, the Koc was 22 (unitless).

Description of key information

Experimental measurement of adsorption/desorption for MTDID 15670 is not required due to its dissociation

in water and rapid hydrolysis. The identified hydrolysis products crotononitrile and dodecyl ethyl sulfide have estimated Koc of 22 and 4.1E+05, respectively. The BF4(-) anion will not adsorb to soil.

Key value for chemical safety assessment

Additional information

An adsorption study for MTDID 15670 was conducted in a Tier I preliminary adsorption test and a Tier II screening adsorption kinetic test, in accordance with OECD 106 “Adsorption-Desorption Using a Batch Equilibrium Method”. After adsorption phase, the % cation in each aqueous phase was measured. It was assumed that the amount of MTDID 15670 adsorbed to soil equals to the total amount added minus the amount measured in the aqueous phase. Since MTDID 15670 is hydrolytically unstable, it is unknown whether the amount of loss in the aqueous phase is due to adsorption or hydrolysis or both. Therefore, this study was considered invalid and a disregarded study.

MTDID 15670 dissociates in water and is subject to hydrolysis. As such, experimental measurement of adsorption/desorption is not required. However, the adsorption characteristics of the hydrolysis products are pertinent to the fate of MTDID 15670 and may be used for risk analysis, classification and labelling, and PBT analysis.

The Koc values of crotononitrile and dodecyl ethyl sulfide were estimated using the equation from European Chemicals Bureau: Technical Guidance Document on Risk Assessment, Chapter 4, Table 4, page 26.  Crotononitrile has a calculated log Koc of 1.34 and Koc of 22 (unitless). Dodecyl ethyl sulfide has a calculated log Koc of  5.62 and Koc of 4.1E+05 (unitless).The BF4(-) anion will not adsorb to soil.