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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12 January 2016 to 24 February 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
GLP Guideline Study
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
Specific details on test material used for the study:
- Physical state: yellow semi-solid
- Analytical purity: 100%
- Expiration date of the lot/batch: 23 November 2017
- Storage condition of test material: room temperature in the dark
Radiolabelling:
no
Test temperature:
30 °C
Details on study design: HPLC method:
EQUIPMENT
- Test utilized a high performance liquid chromatograph. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

DETERMINATION OF DEAD TIME
- Method: The dead time was determined by measuring the retention time of formamide (purity: 99.94%) at 590 mg/L in methanol.

REFERENCE SUBSTANCES
- Solutions of reference standards were prepared in methanol (see table 6).

PREPARATION OF THE SAMPLE SOLUTION
- Test item (0.0555 g) was diluted to 100 mL with methanol to give a concentration of 0.555 g/L.

DETERMINATION OF RETENTION TIMES
- The sample, dead time and reference standard solutions were injected in duplicate using the high performance liquid chromatography (HPLC) parameters as attached. (See Retention time - HPLC parameters document, attached).

- The mobile phase was ramped to 100% tetrahydrofuran shortly after the elution of the last reference standard to elute the highly retained test item components. This was carried out for the sample and sample blank injections only.

EVALUATION OF DATA
Construction of the calibration curve:
- A calibration curve was constructed from the retention time data of the dead time and reference standard solutions (Figure 1, attached).
- Calculation of capacity factors k':
The capacity factors were determined using the following equation:
k’ = (tr– t0)/ t0
where:
k’: capacity factor; tr: retention time (min); t0: dead time (min)

- Calculation of adsorption coefficient:
Log10 Koc value was determined using the following equation:
Log10 Koc = Log10 k’ – A / B
Where:
Koc = adsorption coefficient; k’ = capacity factor; A = intercept of the calibration curve (figure 1, attached); B = slope of the calibration curve (figure 1, attached).

A correlation of log10 k’ versus Log10Koc of the calibration standards was plotted using linear regression. The capacity factor (k’) for the reference standards was calculated from the retention time data of the dead time and reference standard solutions.
Key result
Type:
Koc
Value:
< 17.8 dimensionless
Temp.:
30 °C
Key result
Type:
log Koc
Value:
< 1.25 dimensionless
Temp.:
30 °C
Details on results (HPLC method):
- Typical chromatograms are attached.
- Retention times of the dead time and the retention times, capacity factors and log10 Koc values for the reference standards are shown in Tables7 (attached).
- The calibration curve is shown in Figure 1 (attached).
- The retention times, capacity factor and log10 Koc value determined for the sample are shown in Table 8 (attached).
Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient (Koc) of the test item has been determined to be less than 17.8, log10 Koc <1.25.
Executive summary:

Less than 17.8, log10Koc<1.25, using the HPLC screening method, designed to be compatible with 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

The adsorption coefficient (Koc) of the test item has been determined to be less than 17.8; log10 Koc <1.25 (OECD 121 and EU Method C.19). The result indicates that the substance has a very high mobility in soils (according to P.J. McCall et al., 1981).

Key value for chemical safety assessment

Koc at 20 °C:
17.8

Additional information

Less than 17.8, log10 Koc <1.25, using the HPLC screening method, designed to be compatible with 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 result indicates that the substance has a very high mobility in soils (according to P.J. McCall et al., 19811).

1McCall P.J., Laskowski D.A., Swann R.L., and Dishburger H.J., (1981), “Measurement of sorption coefficients of organic chemicals and their use, in environmental fate analysis”, in Test Protocols for Environmental Fate and Movement of Toxicants. Proceedings of AOAC Symposium, AOAC,

Washington DC.

 

Mobility classification scheme:

Range of Koc

Mobility class

0 - 50

Very high

50 - 150

High

150 - 500

Medium

500 - 2000

Low

2000 – 5000

Slightly

> 5000

Immobile

[LogKoc: 1.25]