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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:
19 January 2017 to 27 January 2017
Reliability:
1 (reliable without restriction)
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
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
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
30 °C
Details on study design: HPLC method:
PREPARATION OF THE DEAD TIME SOLUTION
- The dead time was determined by measuring the retention time of formamide (purity quoted by supplier: 99.94%) at 666 mg/L in methanol.

PREPARATION OF REFERENCE STANDARD SOLUTIONS
- Solutions of reference standards were prepared in methanol as shown in Table 1 (below).

PREPARATION OF THE SAMPLE SOLUTION
- Test item (0.4885 g) was diluted to 10 mL tetrahydrofuran to give a concentration of 48.9 g/L.

DETERMINATION OF RETENTION TIME
- The sample, dead time and reference standard solutions were injected in duplicate using the High Performance Liquid Chromatography (HPLC) parameters shown in the table below.
- The mobile phase was ramped to 100 % tetrahydrofuran shortly after the elution of the last reference standard in order to elute any highly retained test item components. This was carried out for the sample and sample blank injections only.

CALCULATION OF CAPACITY FACTORS
- Capacity factors were determined using the equation k’ = (tr – t0) / t0 where k’ = capacity factor; tr = retention time (min); t0 = dead time (min)

CONSTRUCTION OF THE CALIBRATON CURVE
- A correlation of Log10 k' versus log10 Koc of the reference items was plotted using linear regression (see Figure 1, attached).
- The Log10 Koc values of the reference standards were those quoted in OECD Method 121.

ADSORPTION COEFFICIENT
- The Log10 Koc value was calculated using the equation Log10 Koc = (Log10 k’ – A) / B where Koc = adsorption coefficient; k’ = capacity factor; A = intercept of the calibration curve; B = slope of the calibration curve.
Key result
Type:
log Koc
Value:
> 5.63 dimensionless
pH:
6.3
Temp.:
30 °C
Details on results (HPLC method):
- Typical chromatographs are presented in Appendix 1 (attached).
- The retention times of the dead time and the retention times, capacity factors and Log10 K0c values for the reference standards are shown in Table 2 (attached).
- The calibration curve from which the sample results were taken is presented in Figure 1 (attached).
- The retention times, capacity factors and Log10 Koc values for the sample are shown in Table 3 (below).

TABLE 3 – RETENTION TIMES, CAPACITY FACTOR AND LOG10 Koc VALUES FOR THE SAMPLE

Injection

Retention time (min)

Capacity factor (k’)

Log10 k’

Log10 Koc

1

≥ 43.826

> 12.6

> 1.1

> 5.63

2

≥ 43.828

> 12.6

> 1.1

> 5.63

Overall Log10 Koc range: > 5.63

Mean Log10 Koc: > 5.63

Adsorption coefficient range: > 4.27 x 10E05

Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient of the test item was determined to be > 4.27 x 10E05 with Log10 Koc > 5.63.
Executive summary:

GUIDELINE

The determination was carried out 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. The test utilised a High Performance Liquid Chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

 

RESULTS

The adsorption coefficient of the test item was determined to be > 4.27 x 10E05 with Log10 Koc > 5.63.

Description of key information

The adsorption coefficient of the test item was determined to be > 4.27 x 10E05 with Log10 Koc > 5.63 (OECD 121 and EU Method C.19).

Key value for chemical safety assessment

Additional information

GUIDELINE

The determination was carried out 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. The test utilised a High Performance Liquid Chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

 

RESULTS

The adsorption coefficient of the test item was determined to be > 4.27 x 10E05 with Log10 Koc > 5.63.