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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 May 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
Version / remarks:
(version 2001)
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))
Version / remarks:
(version 2008)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC estimation method
Media:
other: data compared with soil adsorption data of reference substances
Radiolabelling:
no
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Acquity UPLC system equipped with Acquity UPLC TUV detector (Waters, USA)
- Type, material and dimension of analytical column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
- Column temperature: 35°C +/- 1°C
- Flow rate: 0.4 mL/min
- Injection volume: 5 µL
- Detection system: UV (210 nm)

MOBILE PHASE
- Type: 55/45 (v/v) methanol/water
- Solutes for dissolving test and reference substances: stock solutions in methanol; end solutions were 55/45 (v/v) methanol/water

DETERMINATION OF DEAD TIME
- Method: by inert substance which is not retained by the column (formamide)

REFERENCE SUBSTANCES
- Identity: Acetanilide; Monuron; 2,5-Dichloroaniline; Naphthalene; Benzoic acid phenylester; Fenthion; Phenanthrene; 4,4’-DDT

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k': k' = (tr - t0)/t0 where tr = retention time and t0 = mean column dead time
- Determination of the log Koc value: by fitting the k' of test item related peaks into the calibration curve of the log k’ of the reference substances as function of their log Koc
Key result
Type:
Koc
Value:
21 380 dimensionless
Remarks on result:
other: peak 1, area-%: 99
Remarks:
log Koc = 4.33
Type:
Koc
Value:
29 510 dimensionless
Remarks on result:
other: peak 2, area-%: 1.2
Remarks:
log Koc = 4.47
Details on results (HPLC method):
- Retention times of reference substances used for calibration: see table in field 'any other information on results'
- Details of fitted regression line (log k' vs. log Koc): log k’ = 0.312 * log Koc – 0.864 (r = 0.98, n = 16)
- Graph of regression line attached
- Average retention data for test substance: peak 1 - 2.943 min (peak area: 99%), peak 2 - 3.181 min (peak area: 1.2%)

Presented Koc values were calculated by the reviewer from reported log Koc values, as reported Koc values were rounded and expressed in terms of 'value x10^4'

Table: adsorption data of reference substances and test item

Substance

tr,1

[min]

tr,2

[min]

Mean t

(n=2)

Log Koc

Koc

Area-%

Formamide (t0)

0.720

0.726

0.723

 

 

 

Acetanilide

0.926

0.931

 

1.26

 

 

Monuron

1.121

1.121

 

1.99

 

 

2,5-Dichloroaniline

1.267

1.274

 

2.55

 

 

Naphthalene

1.456

1.455

 

2.75

 

 

Benzoic acid phenylester

1.688

1.694

 

2.87

 

 

Fenthion

2.191

2.188

 

3.31

 

 

Phenanthrene

2.428

2.438

 

4.09

 

 

4,4’-DDT

5.663

5.666

 

5.63

 

 

Test item – peak 1

2.944

2.941

2.943

4.33

2.1E+04

99

Test item – peak 2

3.182

3.179

3.181

4.47

2.9E+04

1.2

Notes:

1. In the HPLC chromatogram of the test substance solution, one major peak and several small test item peaks were observed. No further explanation is provided in the report for why only the minor peak with peak area-% of 1.2 was considerd in the Koc evaluation.

2. Log Koc values are based on soil adsorption reference data (according to OECD 121).

Validity criteria fulfilled:
yes
Conclusions:
In the HPLC screening test, the log Koc value of the test item at neutral pH was determined to be 4.33 (Koc = 21380) for the main constituent (peak area: 99%). The log Koc values of a minor constituent (peak area: 1.2%) was determined to be 4.47 (Koc = 29510).
Executive summary:

The potential of Hexalon to adsorb to soil was determined by means of the HPLC estimation method according to OECD TG 121 and in compliance with GLP criteria. In this study, at neutral pH soil-adsorption reference data was used for the determination of the adsorption coefficient (Koc) of the substance. The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 35±1 °C. In the HPLC chromatogram of the test substance solution, one major peak and several small test item peaks were observed (major peak accounting for 99% of the total peak area). The log Koc value of the major component is 4.33 (Koc: 21380), which is selected as key value. The log Koc value of the minor component (1.2% of total peak area) is 4.47 (Koc: 29510).

Description of key information

The potential of Hexalon to adsorb to soil was determined by means of the HPLC estimation method according to OECD TG 121 and in compliance with GLP criteria. In this study, at neutral pH soil-adsorption reference data was used for the determination of the adsorption coefficient (Koc) of the substance. The mobile phase was 55/45 (v/v) methanol/water. The column temperature was 35±1 °C. In the HPLC chromatogram of the test substance solution, one major peak and several small test item peaks were observed (major peak accounting for 99% of the total peak area). The log Koc value of the major component is 4.33 (Koc: 21380), which is selected as key value. The log Koc value of the minor component (1.2% of total peak area) is 4.47 (Koc: 29510).

Key value for chemical safety assessment

Koc at 20 °C:
21 380

Additional information

[LogKoc: 4.33]

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