Cyclopropanecarboxylic acid, 2-[1-(3,3-dimethylcyclohexyl)ethoxy]-2-methylpropyl ester

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:

24-07-2009 to 30-07-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

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))

Deviations:

no

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))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: March 2008 ; signature: June 2008

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

35 °C

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: Perkin Elmer (series 200) HPLC with RI detector
- Type: Nuclleodur 100-5-CN-RP (250 x 4.6 mm id)
- Type, material and dimension of analytical (guard) column: None reported.
- Detection system: RI detection

MOBILE PHASES
- Type: Methanol : purified water (55:45 v/v) Flow rate 1 mL per minute.
- Experiments with additives carried out on separate columns: No
- pH: mobile phase: pH = 7.08
- Solutes for dissolving test and reference substances: None.

DETERMINATION OF DEAD TIME
- Method: The dead time was determined by measuring the retention time of formamide (purity: 99.6%, as certified by supplier), 4000 mg/L solution in methanol : purified water (55:45 v/v). Determined in duplicate.

REFERENCE SUBSTANCES
- Identity: 2-Nitrobenzamide, CAS 610-15-1, Purity > or = 98.7%, log Koc 1.45 (OECD Guideline 121); concentration 500mg/L
- Identity: Methyl benzoate, CAS 93-58-3, Purity 100%, log Koc 1.80 (OECD Guideline 121); concentration 500mg/L
- Identity: Naphthalene, CAS 91-20-3, Purity > or = 99%, log Koc 2.75 (OECD Guideline 121); concentration 500mg/L
- Identity: 1,2,3-trichlorobenzene, CAS 87-61-6, Purity > or = 99.9%, log Koc 3.16 (OECD Guideline 121); concentration 500mg/L
- Identity: Phenanthrene, CAS 85-01-8, Purity > or = 99.2%, log Koc 4.09 (OECD Guideline 121); concentration 500 mg/L
- Identity: DDT, CAS 50-29-3, Purity 98.2%, log Koc 5.63 (OECD Guideline 121); concentration 500 mg/L

DETERMINATION OF RETENTION TIMES
- Quantity of test item introduced in the column: 100 μL per injection for dead time and reference items and/or 100 μL for test item; an aliquot of test item (25.1 mg) was diluted in 50 mL methanol.
- Quantity of reference substances: 100 μL per injection of 2 mL mixture of each reference substances above; the concentration of each reference substance is indicated above injected in duplicate.
- Intervals of calibration: The calibration was performed once specific for the study; with a range of log Koc suitable for the test item which cover both substances suitable for sewage sludge and soil under OECD TG 121 guideline.

REPETITIONS
- Number of determinations: Two.

EVALUATION
- Calculation of capacity factors k': Calculated as a ratio of retention time of retained compounds relative to unretained substances after determination of the column dead time.
- Calculation of retention times: Determined empirically relative to the known column dead time.
- Determination of the log Koc value: Capacity factors (log k') for reference substances were plotted against absorption coefficients (log Koc). The log Koc for the test item was then calculated using the resultant equation for the calibration curve and the experimentally determined log k'.

Type:

log Koc

Value:

ca. 3.88 dimensionless

pH:

7

Temp.:

35 °C

Type:

Koc

Value:

ca. 7 585.78 L/kg

pH:

7

Temp.:

35 °C

Details on results (HPLC method):

EVALUATION
- Calculation of capacity factors k': Calculated as a ratio of retention time of retained compounds relative to unretained substances after determination of the column dead time.
- Calculation of retention times: Determined empirically relative to the known column dead time.
- Determination of the log Koc value: Capacity factors (log k') for reference substances were plotted against absorption coefficients (log Koc). The log Koc for the test item was then calculated using the resultant equation for the calibration curve and the experimentally determined log k'.
- Retention times of reference substances used for calibration: Reference sample injections completed in duplicate.
- Identity: formamide, Retention time average: 3.20 minutes
- Identity: 2-Nitrobenzamide, Retention time average: 3.88 minutes
- Identity: Methyl benzoate, Retention time average: 4.43 minutes
- Identity: Naphthalene, Retention time average: 37.59 minutes
- Identity: 1,2,3-trichlorobenzene, Retention time average: 8.56 minutes
- Identity: Phenanthrene, Retention time average: 12.17 minutes
- Identity: DDT, CAS 50-29-3, Retention time average: 28.29 minutes

- Dead-Time: 3.20 minutes
- Details of fitted regression line (log k' vs. log Koc): Linear regression of all reference substances; A = - 2.245 , B = 2.8812 and R = 0.9738
- Retention data for test item: Single peak. The average retention time; peak 1: 10.91 minutes (Log Koc = 3.88)

Validity criteria fulfilled:

yes

Conclusions:

The test item adsorption coefficient (log Koc) for soil/sewage sludge according to OECD Guideline 121 was estimated to be log Koc = 3.88 at 35°C and ca. pH 7 by HPLC analysis.

Executive summary:

The study was performed to OECD TG 121 guideline under GLP to assess the adsorption coefficient (Koc) of the test item in accordance with GLP using a high-performance chromatography system. The retention times of the test item and selected reference items were accurately measured using HPLC fitted with a cyanopropyl column. The retention times were consistent over the course of the study. The dead time of the instrument was also measured, and capacity factors were calculated for each substance. Calibration curves were constructed by plotting the capacity factor (log k') for the reference substances against their adsorption coefficients (log Koc). Linear regression analysis was performed, and this showed a reasonable relationship between the capacity factors and the adsorption coefficients. The test was performed at a singular approximately neutral pH (pH 7). The adsorption coefficient of the test item was estimated using the calibration curve constructed from all reference items. Under the conditions of this study, the test item adsorption coefficient (log Koc) for soil/sewage sludge was estimated to be log Koc 3.88 at 35°C and ca. pH 7 by HPLC analysis.

Description of key information

log Koc = 3.88, 35 °C, ca. pH 7 and 1 atm, OECD TG 121, 2009

The determination was performed at 35°C (column temperature), however the values can be considered to represent the values at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Kow values were determined. Partition coefficients of the test and reference substances are assumed to vary with temperature in the same way

Key value for chemical safety assessment

Koc at 20 °C:

7 586

Additional information

Key study: OECD TG 121, 2009 : The study was performed to OECD TG 121 guideline under GLP to assess the adsorption coefficient (Koc) of the test item in accordance with GLP using a high-performance chromatography system. The retention times of the test item and selected reference items were accurately measured using HPLC fitted with a cyanopropyl column. The retention times were consistent over the course of the study. The dead time of the instrument was also measured, and capacity factors were calculated for each substance. Calibration curves were constructed by plotting the capacity factor (log k') for the reference substances against their adsorption coefficients (log Koc). Linear regression analysis was performed, and this showed a reasonable relationship between the capacity factors and the adsorption coefficients. The test was performed at a singular approximately neutral pH (pH 7). The adsorption coefficient of the test item was estimated using the calibration curve constructed from all reference items. Under the conditions of this study, the test item adsorption coefficient (log Koc) for soil/sewage sludge was estimated to be log Koc 3.88 at 35°C and ca. pH 7 by HPLC analysis.