Reaction mass of sodium hydrogen N-(1-oxooctadecyl)-L-glutamate and sodium hydrogen N-(1-oxohexadecyl)-L-glutamate

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:

28 May 2013 to 31 May 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with GLP and agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

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)

Type of method:

HPLC estimation method

Radiolabelling:

no

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: Merck-Hitachi LaChrom HPLC system
- Type, material and dimension of analytical (guard) column: LiChrospher CN 100A 250 × 4 mm, 5 μm
- Detection system: UV at 195, 215 and 254 nm

MOBILE PHASES
- Type: Acetonitrile:buffer = 6:4
- pH: 5.4
- Solutes for dissolving test and reference substances: Reference substances were dissolved in acetonitrile except the sodium nitrate. These stock solutions were diluted with eluent. Test material was dissolved in acetonitrile:water (6:4). This stock solution was diluted with eluent.

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (sodium nitrate solution)

REFERENCE SUBSTANCES
- Identity: Sodium nitrate, Acetanilide, Methyl benzoate, Triazophos, Naphthalene, Fenthion and α-Endosulfan

DETERMINATION OF RETENTION TIMES
- Quantity of test material introduced in the column: 10 µg/mL (20 µL injection volume)
- Quantity of reference substances: 10 µg/mL (20 µL injection volume)

REPETITIONS
- Number of determinations: The three calibration series and three test material series were measured alternately (two replicate injections per series).

EVALUATION
- Calculation of capacity factor k': k' =( tR - t0) / t0
- Calculation of retention times: Three series of the reference solutions and the test material were measured alternately. For the determination of the dead time t0 (t0 = retention time of the unretarded component) sodium nitrate solution was injected. The retention times were determined.
- Determination of the log Koc value: The adsorption coefficient Koc was based on the calibration curve prepared by plotting log k' versus log Koc. The capacity factors (k’) were calculated from the dead time and retention times of the reference substances. The log k’ data of the reference substances were plotted against their log Koc values.

Type:

Koc

Value:

< 9.1

Remarks on result:

other: The test material elutes with retention time of 1.57 minutes, before the first reference material; therefore the calibration cannot be applied.

Type:

log Koc

Value:

< 0.97

Remarks on result:

other: The test material elutes with retention time of 1.57 minutes, before the first reference material; therefore the calibration cannot be applied.

Details on results (HPLC method):

- Retention times of reference substances used for calibration: Sodium nitrate 1.56 minutes, Acetanilide 2.76 minutes, Methyl benzoate 3.10 minutes, Triazophos 3.49 minutes, Naphthalene 3.57 minutes, Fenthion 3.77 minutes and α-Endosulphan 4.16 minutes.
- Details of fitted regression line (log k' vs. log Koc): The equation of the curve fitted to the calibration plot is:
log k' = 0.1145 × log Koc - 0.2262 (r² = 0.9611)
- Graph of regression line attached
- Average retention data for test material: 1.57 minutes

Validity criteria fulfilled:

not applicable

Remarks:

the substance meets the specification for which the method is validated

Conclusions:

Under the conditions of the test, the test material eluted with a retention time of 1.57 minutes. This was less than the retention time of the first reference substance. Therefore calculation of the logKoc and Koc was not possible.
An accurate adsorption coefficient could not be determined, however it was concluded that the logKoc and Koc are lower than 0.97 and 9.1, respectively (the logKoc and Koc of the first reference substance).

Executive summary:

The adsorption coefficient of the test material was investigated using the HPLC method in accordance with the standardised guidelines OECD 121 and EU Method C.19. The study was performed under GLP conditions.

The study was carried out using an HPLC system with UV detection. The mobile phase was acetonitrile:buffer (pH 5.4) 6:4. The reference substances used to create the calibration curve were Sodium nitrate, Acetanilide, Methyl benzoate, Triazophos, Naphthalene, Fenthion and α-Endosulfan.

Under the conditions of the test, the test material eluted with a retention time of 1.57 minutes. This was less than the retention time of the first reference substance. Therefore calculation of the logKoc and Koc was not possible.

An accurate adsorption coefficient could not be determined, however it was concluded that the logKoc and Koc are lower than 0.97 and 9.1, respectively (the logKoc and Koc of the first reference substance).

Description of key information

Koc < 9.1 and logKoc < 0.97 (could not be accurately determined due to the low retention time), EU Method C.19, OECD 121, Szabo (2013)

Key value for chemical safety assessment

Koc at 20 °C:

9.1

Additional information

In the key study (Szabo 2013), the adsorption coefficient of the test material was investigated using the HPLC method in accordance with the standardised guidelines OECD 121 and EU Method C.19. The study was performed under GLP conditions. The study was therefore assigned a reliability score of 1 in accordance with the principles for assessing data quality as defined in Klimisch et al. (1997).

The study was carried out using an HPLC system with UV detection. The mobile phase was acetonitrile:buffer (pH 5.4) 6:4. The reference substances used to create the calibration curve were Sodium nitrate, Acetanilide, Methyl benzoate, Triazophos, Naphthalene, Fenthion and α-Endosulfan.

Under the conditions of the test, the test material eluted with a retention time of 1.57 minutes. This was less than the retention time of the first reference substance. Therefore calculation of the logKoc and Koc was not possible.

An accurate adsorption coefficient could not be determined, however it was concluded that the logKoc and Koc are lower than 0.97 and 9.1, respectively (the logKoc and Koc of the first reference substance).

[LogKoc: 0.97]