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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:
4 October 2017 to 12 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
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))
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))
Qualifier:
according to
Guideline:
other: EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption. 2003.
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC estimation method
Media:
soil
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Sponsor and ZMG-197685
- Expiration date of the lot/batch: 09 December 2017
- Purity test date: 28 December 2016
Radiolabelling:
no
Details on study design: HPLC method:

HPLC CONDITIONS
- Instrument: Acquity UPLC system (Waters,USA)
- Detector: Acquity UPLC TUV (Waters)
- Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 μm (Waters)
- Column temperature: 35°C ± 1°C
- Mobile phase: 55/45 (v/v) methanol/water
- Flow: 0.4 mL/min
- Injection volume: 5 μL

RI Detection:

- Temperature: 30°C
- Time constant: 0.2 seconds
- Polarity: positive

UNRETAINED SUBSTANCE, REFERENCE SUBSTANCES AND TEST SUBSTANCE SOLUTIONS
Solution of Unretained Compound
Pure formamide (99.2%, [75-12-7], Alfa Aesar, Karlsruhe, Germany) was used. The solution was prepared by diluting pure formamide in a 1:9 (v:v) ratio with 50/50 (v/v) methanol/water.
The formamide blank solution was 55/45 (v/v) methanol/water.
The formamide solution was prepared in a slightly lower methanol/water ratio in regard to the mobile phase as well as the reference and test item solutions (i.e. 50/50 (v/v) methanol/water instead of 55/45 (v/v) methanol/water). Since the water content is higher than the mobile phase, this small difference would not affect the retention time of an unretained compound such as formamide which was used to determine the dead time. Therefore, the t0 was considered correctly measured with this solution.

Reference Substance Solution
Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol were used. The stock solutions were diluted to obtain an end solution of
55/45 (v/v) methanol/water.
The blank solution for the mixture of reference substances was 55/45 (v/v) methanol/water.

Test Solution
A 25.5 g/L stock solution of the test item was prepared in methanol. The stock solution was 2.5 fold diluted with 55/45 (v/v) methanol/water. The final concentration of the test item solution was 10.2 mg/L.
The test item blank solution was 55/45 (v/v) methanol/water.

INJECTIONS
Reference substance and test item solutions were injected in duplicate. Blank solutions were analyzed by single injection.

DATA HANDLING
- Dead time (t0)= mean retention time of the unretained substance
- Duplicate capacity factors (k') for each reference substance were calculated from the retention times (tr): k'= (tr-t0)/t0
- Log k’ values of the references substances were plotted against the known log Koc values.
- Linear regression analysis (least squares method) resulted in the regression line log k’ = 0.323 log Koc – 0.812 (r=0.98, n=16)
- Capacity factor (k') of the substance was calculated from its retention time and the dead time.
- Log Koc of the substance was calculated by substituting its mean log k’ in the regression line.
- The value of log Koc obtained from duplicate measurements was within ± 0.25 log units.
Key result
Type:
Koc
Value:
4.3 dimensionless
Temp.:
20 °C
Key result
Type:
log Koc
Value:
0.63 dimensionless
Temp.:
20 °C
Details on results (HPLC method):
The chromatogram of the 10.2 mg/L test substance solution showed one major peak.

Table: Results Adsorption coefficient (HPLC estimation method)

Substance

Retention time (min)

log Koc

Koc

tr,1

tr,2

mean

Formamide (t0)

0.698

0.698

0.698

 

 

Acetanilide

0.934

0.933

 

1.26

 

Monuron

1.146

1.144

 

1.99

 

2,5-Dichloroaniline

1.300

1.300

 

2.55

 

Naphthalene

1.511

1.510

 

2.75

 

Fenthion

2.385

2.385

 

3.31

 

Phenanthrene

2.617

2.615

 

4.09

 

4,4’-DDT

6.547

6.550

 

5.63

 

Test item –

peak 1

0.864

0.863

0.864

  0.631

4.3

Validity criteria fulfilled:
yes
Conclusions:
The log Koc was determined to be 0.63 (Koc= 4.3).
Executive summary:

The HPLC estimation method based on soil-adsorption reference data was used for the determination of the adsorption coefficient (Koc) of the substance. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. The mobile phase was 55/45 (v/v) methanol/water and the wavelength of detection 210 nm. The stationary phase contained cyanopropyl chains chemically bonded to silica. Duplicate measurements were performed.

The corresponding log Koc value was determined to be 0.63 (Koc= 4.3).

Description of key information

The HPLC estimation method based on soil-adsorption reference data was used for the determination of the adsorption coefficient (Koc) of the substance. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. The mobile phase was 55/45 (v/v) methanol/water and the wavelength of detection 210 nm. The stationary phase contained cyanopropyl chains chemically bonded to silica. Duplicate measurements were performed.

The corresponding Koc value was determined to be 4.3 (log Koc= 0.63).

Key value for chemical safety assessment

Koc at 20 °C:
4.3

Additional information