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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard test guidelines
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))
Principles of method if other than guideline:
Adsorption coefficient of test chemical 2,3-dimethylphenol (526-75-0) was determined by using HPLC method.
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
25°C
Details on study design: HPLC method:
HPLC Procedure:
The solutions of the test substance and reference substances were prepared in solvent mentioned in 4.3. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(table 3).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor.

Operating Conditions:
HPLC Model No. : Agilent Technologies,1260 Infinity
Flow Rate : 1.0ml/min
Column : ZORBAX Eclipse Plus C18, 4.6×100mm, 3.5 μm
Mobile phase : ACN : water (55:45)
Temperature : 25°C
Detector : Diode Array Detector @210nm
Injector : Autosampler
Injector volume : 10μl
Data Acquisition software : ChemStationOpen lab Control Panel
Analytical monitoring:
not specified
Key result
Sample No.:
#1
Type:
log Koc
Value:
1.759 dimensionless
Temp.:
25 °C
Remarks on result:
other: other details not specified
Details on results (HPLC method):
The Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical 2,3-dimethylphenol (526-75-0) was determined to be 1.759 ± 0.001 at 25°C
Transformation products:
not specified

Table 1:

Reference substance

 

Log Koc

Rt1

Rt2

Rt3

Mean Rt ± S.D.

k

Log k

Urea

NA

0.887

0.887

0.888

0.887±0.001

0

0

Xylene

2.58

6.241

6.232

NA

6.2365±0.006

6.031

0.7804

Ethylbenzene

2.649

6.359

6.355

NA

6.357±0.003

6.1669

0.7901

Toluene

2.369

4.378

4.382

NA

4.38±0.003

3.938

0.5953

Naphthalene

2.75

6.127

6.218

NA

6.1725±0.064

5.9589

0.7752

Phenol

1.32

1.455

1.455

NA

1.455±0.000

0.6404

-0.1936

phenanthrene

4.09

11.996

11.779

NA

11.8875±0.153

12.4019

1.0935

 

Table 2:

Test substance

K

Log k

Koc by Generalized Calibration

Graph

 

Mean of Log Koc ± S.D.

 

Rt1

2.203

1.483

0.171

1.76

1.759±0.001

 

Rt2

2.201

1.481

0.17

1.759

 

Validity criteria fulfilled:
yes
Conclusions:
The Adsorption Coefficient of test substance 2,3-dimethylphenol (526-75-0) was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 1.759 ± 0.001 at 25°C. Thus based on the result it is concluded that the test substance 2,3-dimethylphenol (526-75-0) has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.
Executive summary:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solventsA test item solution was prepared by accurately weighing 5 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 500 mg/l. The pH of test substance was 6.6.Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances Xylene, Ethylbenzene, Toluene, Naphthalene, Phenol, phenanthrene were chosen having Koc value range from 1.32 to 4.09.The Log Koc value of test chemical was determined to be 1.759 ± 0.001dimensionless at 25°C.This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Description of key information

The Adsorption Coefficient of test substance 2,3-dimethylphenol (526-75-0) was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 1.759 ± 0.001 at 25°C. Thus based on the result it is concluded that the test substance 2,3-dimethylphenol (526-75-0) has a low sorption to soil and sediment and therefore has  moderate migration potential to ground water.

Key value for chemical safety assessment

Koc at 20 °C:
57.41

Additional information

Various studies including experimental studies and studiy from authorative database for adsorption (KOC) endpoint of target chemical 2,3-dimethylphenol (Cas no. 526-75-0) were summarized as follows:

In an experimental study,the adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solventsA test item solution was prepared by accurately weighing 5 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 500 mg/l. The pH of test substance was 6.6.Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances Xylene, Ethylbenzene, Toluene, Naphthalene, Phenol, phenanthrene were chosen having Koc value range from 1.32 to 4.09.The Log Koc value of test chemical was determined to be 1.759 ± 0.001dimensionless at 25°C.This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

In another study from authorative database (HSDB by US EPA; 2017) indicate the Koc of 2,3-dimethylphenol as 630,using a structure estimation method based on molecular connectivity indices. This estimated Koc value suggests that 2,3dimethylphenol is expected to have low mobility in soil.

Thus all available studies for adsorption endpoint concluded that the test substance 2,3-dimethylphenol (Cas no. 526-75-0) is expected to have low mobility in soil and sediment compartment.