Registration Dossier

Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
16th - 27th June 1907
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted in accordance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
GLP compliance:
yes
Type of method:
batch equilibrium method
Media:
soil

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): L-2-Chloropropionic acid referred to as AD0381 in the study report.
- Physical state: Liquid
- Analytical purity: 97.2%w/w
- Purity test date: 23rd May 1997
- Lot/batch No.: Batch 19
- Expiration date of the lot/batch: Not specified
- Specific activity (if radiolabelling): 8800 Bq microgrammes -1
- Locations of the label (if radiolabelling): C14 – location not specified
- Expiration date of radiochemical substance (if radiolabelling): Not specified
- Stability under test conditions: Not specified
- Storage condition of test material: Sampled stored under refrigeration in its original container until required. No storage conditions specified for the radio labelled material.
Radiolabelling:
yes

Study design

Test temperature:
No temperature specified for the test system. Samples were centrifuged at 4oC.

Batch equilibrium or other method

Analytical monitoring:
no
Duration of adsorption equilibrationopen allclose all
Sample No.:
#1
Duration:
24 h
Initial conc. measured:
25 other: mg/L test substance
pH:
5.7
Sample No.:
#2
Duration:
24 h
Initial conc. measured:
25 other: mg/L test substance
pH:
6.2
Sample No.:
#3
Duration:
24 h
Initial conc. measured:
25 other: mg/L test substance
pH:
8.2
Duration of desorption equilibrationopen allclose all
Sample no.:
#1
Duration:
24 h
pH:
5.7
Sample no.:
#2
Duration:
24 h
pH:
6.2
Sample no.:
#3
Duration:
24 h
pH:
8.2

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
< 9.1
% Org. carbon:
0.3
Remarks on result:
other: Measured at pH 5.7, sandy soil
Type:
Koc
Value:
2.1
% Org. carbon:
1.3
Remarks on result:
other: Measured at pH 6.2, sandy loam soil
Type:
Koc
Value:
2
% Org. carbon:
16.8
Remarks on result:
other: Measured at pH 8.2, loam soil

Any other information on results incl. tables

Summary of Results

Soil

% Adsorption

Mean Kd

Mean Koc

% Desorption

pH 5.7 Sand

A

<0.41

<0.027

<9.1

<1

B

0.81

<1

C

0.41

<1

pH 6.2 Loamy Sand

A

0.41

0.27

2.1

<1

B

0.41

<1

C

0.82

<1

pH 8.2 Loam

A

4.9

0.033

2.0

<1

B

4.9

<1

C

5.3

<1

 

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The soil kinetics test results showed <1% adsorption of [14C]L-2-chloropropionic acid on the sand and sandy loam soils, with an average of 5% being adsorbed onto the loam soil. Equilibrium was attained after 2 hours. The soil adsorption data was ultimately used to determine the mean adsorption distribution coefficient (Koc) of the test substance. In pH 5.7 sand the Koc was <9.1, in pH 6.2 sandy loam, 2.1 and in pH 8.2 loam, 2.0.

The results from the soil desorption test showed, 1% desorption for all three soil types.
The overall recoveries for the soil sorption and desorption gave a recovery of 95 – 100% of the applied radioactivity, indicating that the data is quantitative.


Executive summary:

A GLP study was performed in accordance with OECD 106 to determine the soil sorption and desorption of radio labelled L-2-chlorpropionic acid.

 The test was performed in triplicate in three different soil types, sand (pH 5.7), sandy loam (pH 6.2) and loam (pH 8.2) with an initial nominal concentration of 25 mg/L of the test substance.

Liquid scintillation counting (LSC) was used to determine the concentration of the test substance in the aqueous medium.

A preliminary test was performed to validate the analytical method and assess the adsorption characteristics of the test substance with respect to PTFE and glass.

The soil kinetic test was performed in triplicate for each test system. For each soil type, a test substance blank, a soil-less control and a full test system were performed. After 2, 4, 8 and 24 hours, tubes were removed, centrifuged for 10 minutes at 10000rpm and triplicate 4ml aliquots of the supernatant removed for analysis.

No tubes were returned to the test system after sampling; sufficient tubes were set up for each sampling period.

After the 24 hour sample had been completed the remaining supernatant volume was measured. This volume, in addition to the 12mls removed for the analysis, formed the initial volume for the calcium chloride solution in the subsequent desorption test.

 

For the desorption test the appropriate volume of 0.01M Calcium chloride solution was added to the respective centrifuge tubes containing the soil subjected to the adsorption process. These tubes were ‘rolled’ for 24 hours. After centrifugation and removal of triplicate 4ml aliquots for analysis, the remaining supernatant was removed and the original volume of fresh calcium chloride solution added. After a further 24 hours the centrifugation and sampling process was repeated.

 

The preliminary test showed no appreciable adsorption of the test substance to PTFE or glass and that the analytical method was reproducible and sufficiently sensitive for the study.

The soil kinetics test results showed <1% adsorption of the test substance on the sand and sandy loam soils with an average of 5% being adsorbed onto the loam soil. Equilibrium was attained after 2 hours. The soil adsorption data was ultimately used to determine the mean adsorption distribution coefficient (Koc) of the test substance. In pH 5.7 sand the Koc was <9.1, in pH 6.2 sandy loam, 2.1 and in pH 8.2 loam, 2.0.

 

The results from the soil desorption test showed, 1% desorption for all three soil types.

The overall recoveries for the soil sorption and desorption gave a recovery of 95 – 100% of the applied radioactivity, indicating that the data are quantitative.