Octanoic acid, 2-phenoxyethyl 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:

05 Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP 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))

Version / remarks:

adopted in 2001

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))

Version / remarks:

adopted in 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Food and Consumer Product Safety Authority, The Netherlands

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test temperature:

35 ± 0.1 °C

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: HPLC
- Type: Alliance Separation Module 2695 (Waters, Milford, MA, USA)
- Type, material and dimension of analytical (guard) column: Hypersil BDS-CN, 150 mm x 4.6 mm, dp = 5 µm (Thermo Fisher Scientific, Waltham, MA, USA)
- Detection system: Dual λ Absorbance Detector 2487 (Waters); 210 nm

MOBILE PHASES
- Type: 55/45 (v/v) methanol/water
- Experiments with additives carried out on separate columns: no
- pH: According to the guidelines, the determination of the Koc for test substances that are ionized for at least 10% within pH 5.5 to 7.5 should be performed with both the ionized and non-ionized form. Therefore, the pKa values of the test substance were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International San Francisco, CA, USA). Based on the calculations, the HPLC analysis was performed at neutral pH.
- Solutes for dissolving test and reference substances: 1) Test substance: An 2504n 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 25 mg/L. 2) Reference substances: Stock solutions of the reference substances at concentrations of ~ 1g/L in methanol were used. The stock solutions were diluted to obtain an end solution of 55/45 (v/v) methanol/water. 3) 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.

REFERENCE SUBSTANCES
- Identity: Acetanilide (103-84-4), Atrazine (1912-24-9), Monuron (150-68-5), 2,5-Dichloroaniline (95-82-9), Benzoic acid phenylester (93-99-2), Fenthion (55-38-9), Phenanthrene (85-01-8), 4,4'-DDT (50-29-3)

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 µL
- Quantity of reference substances: 10 µL

REPETITIONS
- Number of determinations: The reference substance and test substance solutions were injected in duplicate.

EVALUATION
- Calculation of capacity factors k': The capacity factor of each compound was calculated from its retention time.
- Determination of the log Koc value: The log k' values of the reference substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the last squares method. The coefficient of correlation was calculated. The log Koc value for the test substance was calculated by substituting its mean log k' in the calibration curve.

Type:

log Koc

Value:

4.16

Temp.:

35 °C

Type:

Koc

Value:

14 400

Temp.:

35 °C

Details on results (HPLC method):

- Retention times of reference substances used for calibration: see table 1
- Graph of regression line attached
- Average retention data for test substance: 3.869 min

Table 1: Retention times of reference substances

Substance	Tr, 1 [min]	Tr, 2 [min]
Formamide	2.002	2.002
Acetanilide	2.249	2.248
Monuron	2.432	2.430
2,5-Dichloroaniline	2.463	2.461
Benzoic acid phenylester	2.967	2.962
Fenthion	3.608	3.600
Phenanthrene	3.729	3.718
4,4’-DDT	5.877	5.853

Description of key information

The substance has a high adsorption potential. 

Key value for chemical safety assessment

Koc at 20 °C:

14 400

Additional information

The adsorption potential of 2-Phenoxyethyl octanoate (CAS 23511-73-1) was investigated in a GLP-study conducted according to OECD guideline 121 and guideline EC no. 440/2008, Part C. The HPLC analysis was performed at neutral pH and a temperature of 35°C. The determined Koc was 14400 (log Koc 4.16).