Magnesium octadecylbenzenesulphonate

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:

03 April 2019 to 29 May 2019

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))

Qualifier:

according to guideline

Guideline:

other: EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot/batch No.of test material: E01255-297
- Expiration date of the lot/batch: 31 December 2022

Radiolabelling:

no

Details on study design: HPLC method:

ANALYTICAL CONDITIONS
- Apparatus: Acquity UPLC system (Waters, Milford, MA, USA)
- Type: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
- Type, material and dimension of analytical (guard) column:
- Detection system: Acquity UPLC TUV detector (Waters)
- Column temperature: 35 °C ± 1 °C
- Injection volume: 5 µL
- Mobile phase: methanol/water
- Flow: 0.4 mL/min
- UV detection: 210 nm

SOLUTION PREPARATIONS
- Unretained compound: Formamide
- Reference substances: Acetanilide (purity >99.9 %); Monuron (purity 99.9 %); 2,5-Dichloroaniline (purity 99.9 %); Naphthalene (purity 100 %); Benzoic acid phenylester (purity >99.9 %); Fenthion (purity 98.6 %); Phenanthrene (purity 98.5 %); 4,4’-DDT (purity 98.7 %). The log Koc values of the reference substances are based on soil adsorption data reported in OECD 121 guideline.
- Methodology:
A 5 g/L stock solution of formamide (99.2 %) 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.

Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol or acetonitrile 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.

A 2000 mg/L stock solution of the test item was prepared in THF. The stock solution was 100-fold diluted with 55/45 (v/v) methanol/water. The final concentration of the test item solution was 20.0 mg/L. A test item blank solution in THF was 100-fold diluted with 55/45 (v/v) methanol/water.

Reference substance and test item solutions were injected in duplicate. Blank solutions were analyzed by single injection.

Key result

Type:

log Koc

Value:

2.75 dimensionless

Temp.:

35 °C

Remarks on result:

other: 91 % peak area. This peak is a cluster of peaks with a retention time range from 1.28 - 1.86 minutes which corresponds to a log Koc range of 1.99 - 3.31.

Type:

log Koc

Value:

> 5.63 dimensionless

Temp.:

35 °C

Remarks on result:

other: 5.8 % peak area

Type:

log Koc

Value:

> 5.63 dimensionless

Temp.:

35 °C

Remarks on result:

other: 2.9 % peak area

Details on results (HPLC method):

In the chromatogram of the test solution, one major peak and two small test item peaks were observed. Detailed results of the HPLC method are given in the table below. The calibration curve of the log k’ of the reference substances as function of log Koc are attached. The equation of the regression line was: log k’ = 0.325 x log Koc – 0.823 (r = 0.98, n = 16).

Validity criteria fulfilled:

yes

Conclusions:

Using the HPLC method at a neutral pH, soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test material. The log Koc value for the major peak was determined to be 2.75 (this peak is a cluster of peaks with a retention time range from 1.28 - 1.86 minutes, this corresponds with a log Koc range of 1.99 - 3.31).

Executive summary:

The study was performed based on procedures in the OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC); EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC); EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption. Using the HPLC method at a neutral pH, soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test material. The log Koc value for the major peak was determined to be 2.75 (this peak is a cluster of peaks with a retention time range from 1.28 - 1.86 minutes, this corresponds with a log Koc range of 1.99 - 3.31).

Description of key information

The study was performed based on procedures in the OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC); EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC); EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption. Using the HPLC method at a neutral pH, soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test material. The log Koc value for the major peak was determined to be 2.75 (this peak is a cluster of peaks with a retention time range from 1.28 - 1.86 minutes, this corresponds with a log Koc range of 1.99 - 3.31).