cis-2-tert-butylcyclohexyl acetate

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:

9 Dec 2011 to 31 Aug 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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))

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

GLP compliance:

yes

Type of method:

HPLC estimation method

Radiolabelling:

no

Test temperature:

- Column temperature: 35 °C ± 1 °C

Details on study design: HPLC method:

- Equipment: Instrument: Alliance Separation Module 2695 (Waters, Milford, MA, USA), Detector: Dual λ Absorbance Detector 2487 (Waters) Column Hypersil BDS-CN, 150 mm x 4.6 mm i.d., dp = 5 µm (Thermo Fisher Scientific, Waltham, MA, USA), Column temperature: 35 °C ± 1 °C, Mobile phase: 55/45 (v/v) methanol/water, Flow: 1 mL/min, Injection volume: 10 µL, UV detection: 210 nm.
- Preparation of solutions: Solution of the unretained compound: A 4.81 g/L stock solution of formamide (99.8 %, [75-12-7], Acros Organics, Geel, Belgium) in methanol was used. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/water. The formamide blank solution was 55/45 (v/v) methanol/water. Reference substance solutions: Stock solutions of the reference substances (Acetanilide, Atrazine, Monuron, 2,5-Dichloroaniline, Benzoic acid phenylester, Fenthion, Phenanthrene) at concentrations of approximately 1 g/L in methanol were used. The stock solutions were diluted to obtain an end solution of 55/45 (v/v) methanol/water. The blank solution for the mixture of reference substances was 55/45 (v/v) methanol/water. Test solution: A 1172 mg/L stock solution of the test substance was prepared in methanol. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/water. The final concentration of the test substance solution was 128.9 mg/L. The test substance blank solution was 55/45 (v/v) methanol/water.
- The reference substance and test substance solutions were injected in duplicate. Blank solutions were analysed by single injection.

Key result

Type:

Koc

Value:

1 300 dimensionless

Temp.:

35 °C

Key result

Type:

log Koc

Value:

3.12 dimensionless

Temp.:

35 °C

Details on results (HPLC method):

- Calculation of pKa values: No pKa values for acidic and basic groups in the molecular structure of the test substance in the logarithm range of 1 - 14 were calculated.
- Determination of the Koc: In the chromatogram of the test solution, one test substance peak was observed. It indicated that the two isomers of the test substance eluted as a single peak. The equation of the regression line was: log k’ = 0.371 x log Koc – 1.137 (r = 0.972, n = 14).
- The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of Verdox. The Koc and log Koc value of the test substance at neutral pH was: Koc = 1.3E3 and log Koc 3.12.

Statistics:

A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Koc value for the test substance was calculated by substituting its mean log k’ in the calibration curve. The value of log Koc obtained from duplicate measurements was within  0.25 log units.

Validity criteria fulfilled:

yes

Conclusions:

The Koc value of the test substance at neutral pH was 1300 L/kg (log Koc = 3.12).

Executive summary:

A GLP-compliant study performed in accordance with OECD Guideline 121 (HPLC Method) is available. Solutions of reference substances with known log Koc values based on soil adsorption data and the test substance were analysed by HPLC using a Hypersil BDS-CN column. The log k’ values of reference substances were plotted against the known log Koc values. The log Koc value for the test substance was calculated by substituting its mean log k’ in the calibration curve. Under the conditions of the test, the Koc of Verdox was determined at 1300 L/kg (log Koc = 3.12).

Description of key information

The adsorption coefficient (Koc) of Verdox was determined in a HPLC screening test according to OECD Guideline 121. The log Koc was found to be 3.12 (Koc of 1300 L/kg). This value was used for further calculations. It can be concluded that the substance has a moderate adsorption potential to sediment/soil.

Key value for chemical safety assessment

Koc at 20 °C:

1 300

Additional information

LogKoc: 3.12 at 35 °C.

[LogKoc: 3.12]