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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
07 June 2018 to 10 July 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study was conducted in accordance with international guidelines and in accordance with GLP
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)
Remarks:
Date of Inspection: 18 July 2017 - 20 July 2017 Date on Certfiicate: 28 November 2017
Type of method:
HPLC estimation method
Test temperature:
30 °C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Agilent Technologies 1100 Series
- Type: HPLC system
- Type, material and dimension of analytical (guard) column:
Eclipse XDB-CN 5μm (150 x 4.6 mm i.d.)
- Detection system: variable wavelength (VW); 210 nm (dead time and standards) 280 nm (sample)

MOBILE PHASES
- Type: Methanol: purified water (55:45 v/v)
- Experiments with additives carried out on separate columns: N/A
- pH: 6.1
- Solutes for dissolving test and reference substances:
Sample solution and reference standards: methanol
Dead time solution: mobile phase

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column

REFERENCE SUBSTANCES
- Identity: acetanilide, atrazine, triadimenol, linuron, naphthalene, endosulfan-diol, fenthion, α-Endosulfan, phenanthrene, diclofop-methyl, DDT

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 μL
- Quantity of reference substances: 10 µL

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k':
k' = (tr-t0)/t0
where:
k' = capacity factor
tr = retention time (min)
t0 = dead time (min)

- Construction of the calibration curve:
A correlation of log k' versus log Koc of the reference standards was plotted using linear regression. The capacity factors (k') for the reference standards were calculated using the equation above. Log10 Koc values are those quoted in Method 121 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

- Determination of the log Koc value:
log Koc = (log k' - A)/B
where:
Koc = adsorptopm coefficient
k' = capacity factor
A = intercept of the calibration curve
B = slope of the calibration curve
Key result
Sample No.:
#1
Type:
log Koc
Value:
2.08 dimensionless
Temp.:
30 °C
Matrix:
methanol
Key result
Sample No.:
#1
Type:
Koc
Value:
121 dimensionless
Temp.:
30 °C
Matrix:
methanol
Details on results (HPLC method):
- Retention times of reference substances used for calibration:
Shown in section 'Any other information on results incl. tables below (Tables 25 and 26)
- Details of fitted regression line (log k' vs. log Koc):
y = 0.3172x - 0.7983
R2 = 0.9462
- Graph of regression line attached:
Yes
- Average retention data for test substance:
Retention time - 2.928 mins
Capacity factor - k' = 0.728
Log10 k' = -0.138
Log10 Koc = 2.08

Calibration Data

The retention times of the dead time and the retention times, capacity factors (k') and log10 Koc values for the reference standards are shown in the following two tables.

Table 3

Dead Time

Retention Time (mins)

Mean Retention Time (mins)

Injection 1

Injection 2

Formamide

1.696

1.693

1.695

Table 4

Standard

Retention time (mins)

Mean Retention Time (mins)

Capacity factor (k’)

Log10k’

Log10Koc

 

 

Acetanilide

2.174

2.174

2.174

0.283

-0.549

1.25

Atrazine

2.569

2.569

2.569

0.516

-0.287

1.81

Triadimenol

3.372

3.370

3.371

0.989

-4.69 x 10-3

2.40

Linuron

3.899

3.899

3.899

1.30

0.114

2.59

Naphthalene

3.661

3.661

3.661

1.16

6.46 x 10-2

2.75

Endosulfan-diol

4.755

4.753

4.754

1.81

0.257

3.02

Fenthion

6.162

6.167

6.164

2.64

0.421

3.31

α-Endosulfan

7.319

7.317

7.318

3.32

0.521

4.09

Phenanthrene

7.188

7.191

7.189

3.24

0.511

4.20

Diclofop-methyl

6.189

6.194

6.191

2.65

0.424

4.09

DDT

14.964

14.971

14.967

7.83

0.894

5.63

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

Table 5

Injection

Retention time (mins)

Capacity Factor (k’)

Log10k’

Log10Koc

1

2.928

0.728

-0.138

2.08

2

2.928

0.728

-0.138

2.08

log10 Koc: 2.08

Adsorption coefficient: 121

Discussion

The chromatography demonstrated several minor peaks which are considered to be impurities and therefore have not been reported.

The test item has predicted dissociation constants of 4.1 ± 0.5 and 12.2 ± 0.6 (using ACD/Labs I-Lab 2.0 - ilab.acdlabs.com, algorithm version: v5.0.0.184). Therefore, testing was performed at pH 6.1 with the test item mostly in its non-ionized form.

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.

Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption coefficient of the test item has been determined to be 121, log10 Koc 2.08. These values indicate that the mobility of the test item will be high.
Executive summary:

The adsorption coefficient of the test item has been determined to be 121, log10Koc 2.08 using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001, Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008. These values indicate that the mobility of the test item will be high.

Description of key information

The adsorption coefficient of the test item has been determined to be 121, log10 Koc 2.08 at a temperature of 30 °C. These values indicate that the mobility of the test item will be high.

Key value for chemical safety assessment

Koc at 20 °C:
121

Additional information

The adsorption coefficient of the test item has been determined to be 121, log10 Koc 2.08 using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001, Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008. These values indicate that the mobility of the test item will be high.