Octadecanedioic acid, 1,18-dimethyl 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:

2013

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))

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Radiolabelling:

no

Test temperature:

30°C

Details on study design: HPLC method:

Preparation of sample solution:
Test item (0.1099 g) was diluted to 100 m: with methanol (MeOH) to give a concentration of 1.10 g/L.

Preparation of dead time solution:
The dead time was determined by measuring the retention time of formamide (668 mg/L solution in MeOH:water 55~:45 v/v).

Preparation of reference standards solutions:
Solutions of reference standards (below) were prepared in methonol
- Acetanilide
- Phenol
- Atrazine
- Isoproturon
- Triadimenol
- Linuron
- Naphthalene
- Endosulfan-diol
- Fenthion
- α-Endosulfan
- Diclofop-methyl
- Phenanthrene
- DDT

Determination of retention time
The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:
HPLC System : Agilent Technologies 1100 Series, incorporating autosampler
Column : XSelect CN 5μ (150 x 4.6 mm id)
Column temperature : 30 ºC
Mobile phase : Methanol:water (55:45 v/v), ramped to 100% methanol for sample injections after the retention time of DDT
pH of mobile phase : 6.05
Flow-rate : 1.0 mL/min
Injection volume : 25 μL
UV detector wavelength : 210 nm

As the test item had a high affinity for the stationary phase of the column, the mobile phase was adjusted to 100% methanol shortly after the retention time of DDT to elute the sample.

Data handling:
A calibration curve was constructed from the retention time data of the dead time and reference standard solutions. Capacity factors (k') for the reference standards were calculated.

The adsorption coefficient was caluclated using equation:
Log10 Koc = log10 k' - A / B
where:
k' = capacity factor
A = intercept of the calibration curve
B = slope of the calibration curve

Type:

Koc

Value:

> 427 000 dimensionless

Temp.:

30 °C

Type:

log Koc

Value:

> 5.63 dimensionless

Temp.:

30 °C

Details on results (HPLC method):

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

The retention times, capacity factor anmd log₁₀ Koc value determined for the sample are shown in the following table:

Injection	Retention Time (mins)	Capacity Factor (k)	Log10K	Log10Koc
1	39.645	>13.4	>1.13	>5.63
2	39.645	>13.4	>1.13	>5.63

Overal log₁₀Koc: >5.63

Adsorption coefficient: >4.27 x 10⁵

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient of the test material was assessed according to OECD Guideline 121 and determined to be greater than 4.27 x 10E5, log10Koc >5.63.

Executive summary:

A study was performed to assess the adsorption coefficient of the test item, using the HPLC screening method, designed to be compatible with method 121 of the OECD guidelines for testing of chemicals, 22 January 2001 and method C19 adsorption coefficient of commission regulation (EC) No 440/2008 of 30 May 2008. The adsorption coefficient (Koc) of the test item was determined to be 4.27 x 10⁵, log₁₀Koc >5.63. As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure (Harlan Laboratories Ltd, 2013).

Description of key information

The adsorption coefficient of the test material was assessed according to OECD Guideline 121 and determined to be greater than 4.27 x 10⁵, log₁₀Koc >5.63.

As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

Key value for chemical safety assessment

Koc at 20 °C:

427 000

Additional information

A study was performed to assess the adsorption coefficient of the test item, using the HPLC screening method, designed to be compatible with method 121 of the OECD guidelines for testing of chemicals, 22 January 2001 and method C19 adsorption coefficient of commission regulation (EC) No 440/2008 of 30 May 2008. The adsorption coefficient (Koc) of the test item was determined to be 4.27 x 10⁵, log₁₀Koc >5.63. As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient. Based on the chromatographic data, the test item was considered to be stable during the test procedure (Harlan Laboratories Ltd, 2013).