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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
Study period:
26 July 2016 to 23 April 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Specific details on test material used for the study:
- Purity: 96.6%
- Description: yellow viscous liquid
Details on study design: HPLC method:
Preparation of sample solution
Test item (0.1071 g) was diluted to 100 mL with MeCN to give a concentration of 1.07 g/L.

Preparation of dead time solution
The dead time was determined by measuring the retention time of formamide (purity 99.94%, value quoted by supplier, 752 mg/L solution in MeCN:water 55:45 v/v).

Preparation of reference standard solutions
Solutions of reference standards were prepared in methanol.

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 1200 Series
- Detector type: Ultraviolet (UV)
- Column: Luna CN (150 x 4.6 mm id)
- Column temperature: 30ºC
- Mobile phase: MeCN:water (55:45 v/v)
- pH of mobile phase: 6.35
- Flow-rate: 1.0 mL/min
- Injection volume: 10 μL
- UV detector wavelength: dead time and reference standards: 210 nm
sample: 264 nm
Key result
Sample No.:
#1
Type:
log Koc
Value:
> 5.63
Key result
Sample No.:
#2
Type:
log Koc
Value:
> 5.63
Key result
Sample No.:
#3
Type:
log Koc
Value:
> 5.63
Details on results (HPLC method):
Overall log10 Koc: greater than 5.63
Adsorption coefficient: greater than 4.27 x 10^5

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

 

Peak

Injection

Retention time (mins)

Capacity factor (k')

Log10 k'

Log10 Koc

Mean log10 Koc

Adsorption Coefficient

1

1

22.445

10.5

1.02

>5.63

>5.63

>4.27 x 105

2

22.310

10.4

1.02

>5.63

2

1

36.557

17.8

1.25

>5.63

>5.63

>4.27 x 105

2

34.437

16.7

1.22

>5.63

3

1

60.708

30.1

1.48

>5.63

>5.63

>4.27 x 105

2

54.471

26.9

1.43

>5.63

 

Overall log10 Koc: greater than 5.63

Adsorption coefficient: greater than 4.27 x 105

 

Discussion

As the test item had a high affinity for the stationary phase of the column, the mobile phase was prepared using acetonitrile instead of methanol.

Several peaks were observed with early retention times however these have not been reported as they comprised less than 5% (by area) of the test item.

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.

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the study, the adsorption coefficient of the test item has been determined to be greater than 4.27 x 10^5, log10Koc> 5.63, using the HPLC screening method.
Executive summary:

Under the conditions of the study, the adsorption coefficient of the test item has been determined to be greater than 4.27 x 105, log10Koc> 5.63, using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Description of key information

Under the conditions of the study, the adsorption coefficient of the test item has been determined to be greater than 4.27 x 105, log10Koc> 5.63, using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Key value for chemical safety assessment

Koc at 20 °C:
0

Additional information