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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment
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:
not specified
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Radiolabelling:
no
Test temperature:
30ºC
Details on study design: HPLC method:
Preparation of the solutions
Solution of the unretained compound
A 1.99 g/L stock solution of formamide in methanol was used. The test solution was prepared by adding 1000 µL of the stock solution to a 5 mL volumetric flask. The flask was filled up to the mark with mobile phase.

The formamide blank solution was prepared by adding 1000 µL of methanol to a 5 mL volumetric flask. The flask was filled up to the mark with mobile phase.

Reference substance solutions
Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol were used. Two mixtures of the reference substances were prepared. Each mixture contained four reference substances and was prepared by adding 1000 µL of each stock solution to a 10 mL volumetric flask. The flask was filled up to the mark with mobile phase.

The blank solution of reference substance was prepared by adding 4000 µL of methanol to a 10 mL volumetric flask. The flask was filled up to the mark with mobile phase.

Reference substance log Koc
Phenol 1.32
N,N-Dimethylbenzamide 1.52
Methylbenzoate 1.80
3,5-Dinitrobenzamide 2.31
Napthalene 2.75
Fenthion 3.31
Phenanthrene 4.09
2,4-DDT 5.63

Test solution
A 5730 mg/L stock solution of the test substance was prepared in methanol. The test solution was prepared by adding 750 µL of the stock solution to 250 µL water. The final test substance concentration of the test solution was 2149 mg/L.

The test substance blank solution was prepared by adding 750 µL of methanol to 250 µL water.

Injections

The reference substance and test substance solutions were injected in duplicate. Blank solutions were analysed by single injection.
Computational methods:
The capacity factor (k’) of each compound was calculated from its retention time. 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 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.
Key result
Type:
log Koc
Value:
4.29 dimensionless
Key result
Type:
Koc
Value:
19 600 L/kg
Details on results (HPLC method):
- Retention times of reference substances used for calibration:

Substance tr,1 tr,2
Formamide (t0) 1.755 1.774
Phenol 2.602 2.612
N,N-Dimethylbenzamide 2.366 2.381
Methylbenzoate 2.749 2.758
3,5-Dinitrobenzamide 3.089 3.099
Napthalene 3.605 3.620
Fenthion 5.593 5.624
Phenanthrene 5.226 5.252
2,4-DDT 9.495 9.537

Major component 5.990 5.996

- Average retention data for test substance: 5.993
Validity criteria fulfilled:
yes
Conclusions:
The Koc of the test substance is 1.96 x10^4 L/kg and the log Koc is 4.29.
Executive summary:

The HPLC method was used to determine the adsorption coefficient. The log Koc was calculated using linear regression analysis on the calibration curve. The Koc of the test substance is 1.96 x104 L/kg and the log Koc is 4.29.

Description of key information

The HPLC method was used to determine the adsorption coefficient. The log Koc was calculated using linear regression analysis on the calibration curve. A log Koc of 4.29 (19,600 L/kg) can be taken as representative for AC-6000.

Key value for chemical safety assessment

Koc at 20 °C:
19 600

Additional information

A GLP-compliant is available which is performed in accordance with OECD Guideline 121 (HPLC Method). (NOTOX B.V., 2008). A methanol/water 55/45 v/v % mixture at neutral pH was applied. AC-6000 has a log Koc value of 4.29 (equivalent Koc = 19,600 L/kg.

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