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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Between 22 March and 02 April 2012.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.
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))
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
other: Not applicable.
Radiolabelling:
no
Details on study design: HPLC method:
Preparation of sample solution
Test item (4.0974 g) was diluted to 100 mL with methanol for a concentration of 4.10 x 104 mg/L.

Preparation of dead time solution
The dead time was determined by measuring the retention time of formamide (purity* 99%, 682 mg/L solution in mobile phase). * Value quoted by supplier

Preparation of reference standard solution
Solution of reference standards were prepared in methanol (Please see table below in materials and methods section of this summary).

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, Polymer Laboratories Evaporative Light Scattering Detector 2100 (ELSD)
Column : Luna CN 5µ (150 x 4.6 mm id)
Column temperature: 30 ºC
Mobile phase : Methanol:water (55:45 v/v)
pH of mobile phase: 7.1 adjusted with 0.1 M sodium hydroxide
Flow-rate : 1.0 mL/min
Injection volume: 5 µL
UV detector wavelength : dead time and reference standards: 210 nm
ELSD Gas flow: 1.0 SLM
Nebulizer temperature: 40 degrees centigrade
Evaporator temperature: 60 degrees centigrade

The dead time and reference standards were detected using UV, while the test item was detected using an ELSD. Although there was a time difference in analyte detection between these detectors as they are connected in series, it was consider not significant.

Construction of calibration curve
A calibration curve was constructed from the retention time data of the dead time and reference standard solutions (Figure 3.1). The capacity factors k' for the reference standards were calculated using Equation 3.1.

Adsorption coefficient of sample
The capacity factor was calculated using Equation 3.1 (Attachment 1) and the log10Koc value determined using Equation 3.2 (Attachment 1) with reference to the calibration curve (Figure 3.1 - Attachment 2).

















Analytical monitoring:
no
Type:
log Koc
Value:
3.25 dimensionless
Type:
Koc
Value:
1 770 dimensionless
Transformation products:
not measured
Details on results (Batch equilibrium method):
In this case Not applicable.
Statistics:
None stated.

Calibration

The retention times of the dead time and the retention times, capacity factors (k') and log10Kocvalues for the reference standards are shown in the two following tables:

 

Table 3.2

 

Dead Time

Retention Time (mins)

Mean Retention Time (mins)

Injection 1

Injection 2

Formamide

2.002

1.997

2.000

 

 

Table 3.3

 

Standard

Retention Time (mins)

Mean Retention Time (mins)

Capacity Factor (k)

Log10 k

Log10 Koc

Injection 1

Injection 2

Acetanilide

2.357

2.357

2.357

0.179

-0.748

1.25

Phenol

2.303

2.303

2.303

0.152

-0.819

1.32

Atrazine

2.556

2.556

2.556

0.278

-0.555

1.81

Isoproturon

2.745

2.745

2.745

0.373

-0.428

1.86

Triadimenol

2.886

2.881

2.884

0.442

-0.354

2.40

Linuron

3.129

3.134

3.132

0.566

-0.247

2.59

Naphthalene

3.780

3.780

3.780

0.890

-5.04 x 102

2.75

Endosulfan-Diol

3.120

3.120

3.120

0.560

-0.252

3.02

Fenthion

4.373

4.368

4.371

1.19

7.40 x 10-2

3.31

Phenanthrene

5.792

5.797

5.795

1.90

0.278

4.09

Diclofop-methyl

5.350

5.350

5.350

1.68

0.224

4.2

DDT

12.119

12.119

12.119

5.06

0.704

5.63

Adsorption coefficient of sample

The retention times, capacity factor and log10Kocvalue determined for the sample are shown in the following table:

 

Table 3.4

 

Injection

Retention Time (mins)

Capacity Factor (k)

Log10k

Log10Koc

1

3.817

0.909

-4.15 x 10-2

3.27

2

3.767

0.884

-5.36 x 10-2

3.23

 

Mean log10Koc:                      3.25

Adsorption coefficient:          1.77 x 103

Validity criteria fulfilled:
yes
Conclusions:
The adsorption coefficient (Koc) of the test item has been determined to be 1.77 x 103,log10 Koc 3.25. This value indicates that the test item has low mobility.
Executive summary:

Test System

The determination was carried out 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.

Discussion

The test item had no dissociation constants within the environmentally relevant pH range.

 

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.

 

A estimate of the adsorption coefficient was calculated as log Koc2.71 using KOCWIN v2.00 (Feb 2009) © 2000 U.S. Environmental Protection Agency based on information on the test item provided by the Sponsor. This result used the calculated partition coefficient, but if the test result is used from Harlan Laboratories Ltd project 41200268, log Pow4.11, then the estimate is revised to log Koc3.13.

Conclusion

The adsorption coefficient (Koc) of the test item has been determined to be 1.77 x 103, log10 Koc 3.25. This value indicates that the test item has low mobility.

Description of key information

Koc was determined to be 1770; study conducted in accordance with OECD 121; Fox (2012)

Key value for chemical safety assessment

Koc at 20 °C:
1 770

Additional information

In a GLP compliant adsorption coefficient study conducted in accordance with standardised guidelines, the adsorption coefficient of the test substance was determined using the HPLC screening method. Under the conditions of the test, the Koc of the substance was determined to be 1770.

[LogKoc: 3.25]