Ethyl trans-2,2,6-trimethylcyclohexanecarboxylate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 January 1996 to 18 March 1996

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)

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Analysis of samples
Samples:
An aliquot (20.0 ml) of each sample was drawn through a C18 Bond Elut solid phase extraction cartridge before being eluted with methanol (5.0 ml).
Standards:
Standard solutions of test material were prepared in methanol at a nominal concentration of 20 mg/l.

Details on matrix:

Samples of the three soil types were air dried, ground to less than 2 mm and stored in the dark at ambient temperature until required for testing.
Soil 1 - very strongly to strongly acidic soil (pH 4.5 - 5.5)
Soil 2 - moderately to slightly acidic soil (pH 5.5 - 6.5)
Soil 3 - slightly alkaline soil (pH 7.1 - 8.0)
Each soil was characterised with respect to pH, organic carbon content, particle size distribution, cation exchange capacity and exchangeable cations.The moisture content of each soil was determined by drying samples at approximately 105 °C for a minimum time of 12 hours.
Equilibration of each soil sample with calcium chloride solution (0.01 M) was performed by gently shaking the soil and calcium chloride solution together for a period of 24 hours prior to the start of the test.

Details on test conditions:

Preliminary data
Preliminary information was obtained on the water solubility of the test material and its stability over the study testing period.A preliminary test was also performed on each soil type to confirm the validity of the analytical method.
Screening test : adsorption
Preparation of test solution:An aliquot (0.0850 g) of test material was diluted to 100 ml with methanol. This was further diluted by a factor of 100 with 0.01 M calcium chloride (CaCI2) solution.
Sample control preparation and treatment:
Duplicate wet soil/ test solution mixtures, and a wet soil/ 0.01M CaCI2 solution (blank) were prepared for each soil type. A control consisting of test solution with no soil was also prepared. Each sample was protected from light in order to minimise photodegradation.The samples were shaken continuously for a period of time sufficient to establish the adsorption equilibrium.
Agitation was adequate to maintain the soil in suspension, but not so vigorous as to cause the breakdown of the soil structure.
After equilibration, the samples were centrifuged to separate the phases and an aliquot (20.0 ml) taken for analysis by GC.
Screening test : desorption
The desorption step of the procedure was performed on samples that adsorbed significantly (i.e. > 25%).
The supernatant removed during the adsorption step was replaced with an equivalent volume (20.0 ml) of 0.01M CaCI2 solution. The samples were shielded from light then equilibrated by shaking continuously for a period of time equivalent to that in the adsorption step.After equilibration, the samples were centrifuged to separate the phases and an aliquot (20.0 ml) of the supernatant taken for analysis by GC.The desorption step was repeated using a further volume (20.0 ml) of 0.01M CaCI2 solution.

Key result

Type:

Koc

Value:

893 dimensionless

Temp.:

25 °C

Remarks on result:

other: soil type 1

Key result

Type:

Koc

Value:

596 dimensionless

Temp.:

25 °C

Remarks on result:

other: soil type 2

Key result

Type:

Koc

Value:

877 dimensionless

Temp.:

25 °C

Remarks on result:

other: soil type 3

adsorption

Soil type	Mean test material adsorbed (% w/w)	Mean adsorption coefficient, K	Mean adsorption coefficient as a function of organic carbon content, Koc
1	51.3	5.36	893
2	68.2	10.7	596
3	51.5	5.26	877

 desorption          

Soil type	Mean test material desorbed (% w/w)	Mean test material remaining on adsorbent after desorption step (% w/w)
1	35.5	64.5
2	34.4	65.6
3	33.9	66.1

Validity criteria fulfilled:

yes

Conclusions:

see below

Executive summary:

STUDY TITLE: SOIL ADSORPTION/ DESORPTION SCREENING TEST

TEST MATERIAL: ET-344-SP

The adsorption/ desorption characteristics in three different soil types have been determined in accordance with OECD Guideline 106, "Adsorption/Desorption", OECD Guidelines for the Testing of Chemicals, 12 May 1981. The results are summarized below:

adsorption

Soil type	Mean test material adsorbed (% w/w)	Mean adsorption coefficient, K	Mean adsorption coefficient as a function of organic carbon content, Koc
1	51.3	5.36	893
2	68.2	10.7	596
3	51.5	5.26	877

 desorption          

Soil type	Mean test material desorbed (% w/w)	Mean test material remaining on adsorbent after desorption step (% w/w)
1	35.5	64.5
2	34.4	65.6
3	33.9	66.1

Description of key information

STUDY TITLE: SOIL ADSORPTION/ DESORPTION SCREENING TEST

TEST MATERIAL: ET-344-SP

The adsorption/ desorption characteristics in three different soil types have been determined in accordance with OECD Guideline 106, "Adsorption/Desorption", OECD Guidelines for the Testing of Chemicals, 12 May 1981. The results are summarized below:

adsorption

Soil type	Mean test material adsorbed (% w/w)	Mean adsorption coefficient, K	Mean adsorption coefficient as a function of organic carbon content, Koc
1	51.3	5.36	893
2	68.2	10.7	596
3	51.5	5.26	877

 desorption          

Soil type	Mean test material desorbed (% w/w)	Mean test material remaining on adsorbent after desorption step (% w/w)
1	35.5	64.5
2	34.4	65.6
3	33.9	66.1

Key value for chemical safety assessment

Koc at 20 °C:

788.7

Additional information

The key Koc value for the chemical safety assessment is the mean value of the three mean Koc values for the three soil types as detailed in the table above.