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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data is from HSDB and PubChem authoritative database
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Soil adsorption coefficient (Koc) of test chemical was estimated using a logKow and a regression derived equation.
GLP compliance:
not specified
Type of method:
other: No data available
Media:
soil
Radiolabelling:
not specified
Analytical monitoring:
not specified
Computational methods:
- Other: Koc value of test chemical was estimated using a logKow of 5.82 and a regression derived equation.
Type:
Koc
Value:
35 000 dimensionless
Remarks on result:
other: Log Koc= 4.544
Transformation products:
not specified

According to a classification scheme, the estimated Koc value suggests that test chemical is expected to be immobile in soil.

Validity criteria fulfilled:
not specified
Conclusions:
The adsorption coefficient (Koc) value of test chemical was estimated to be 35,000 calculated using a logKow and a regression derived equation.
Executive summary:

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a logKow of 5.82 and a regression derived equation. The adsorption coefficient (Koc) value of test chemicall was estimated to be 35,000 (Log Koc = 4.544). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

Description of key information

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 solvents. A test item solution was prepared by accurately weighing 20 mg of test item and diluted with methanol up to 10 ml. Thus, the test solution concentration was 2000 mg/l. The sample was prepared by adjusting the pH with 0.005% formic acid and filtered through a 0.22 μm syringe filter. The pH of test substance was 3.5. 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.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 were 2-nitrobenzamide, 3-nitrobenzamide, Aniline, 3,5-dinitrobenzamide, 1,2,3-trichlorobenzene, phenanthrene and DDT were chosen having Koc value range from 1.19 to 4.83. The Log Koc value was determined to be 4.267 ± 0.007 at 25°C.This log Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

Key value for chemical safety assessment

Koc at 20 °C:
18 492

Additional information

Various experimental studies and predicted data of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

In an experimental study from study report, 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 solvents. A test item solution was prepared by accurately weighing 20 mg of test item and diluted with methanol up to 10 ml. Thus, the test solution concentration was 2000 mg/l. The sample was prepared by adjusting the pH with 0.005% formic acid and filtered through a 0.22 μm syringe filter. The pH of test substance was 3.5. 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.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 were 2-nitrobenzamide, 3-nitrobenzamide, Aniline, 3,5-dinitrobenzamide, 1,2,3-trichlorobenzene, phenanthrene and DDT were chosen having Koc value range from 1.19 to 4.83. The Log Koc value was determined to be 4.267 ± 0.007 at 25°C.This log Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

In an supporting study from authoritative database (HSDB and PubChem, 2017) for the target chemical, adsorption experiment was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a logKow of 5.82 and a regression derived equation. The adsorption coefficient (Koc) value of test chemical was estimated to be 35,000 (Log Koc = 4.544). This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

Another adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (OECD SIDS, 2006). The adsorption coefficient (Koc) value was calculated using a logKow of 5.51 and a QSAR TGD hydrophobic and non-hydrophobic method. The adsorption coefficient (Koc) value of test chemical was estimated to be 7677.1 (Log Koc = 3.89) by TGD-non-hydrophobic method and 36568 (Log Koc = 4.56) by TGD-hydrophobic method, respectively. This Koc value indicates that the test chemical has a strong to very strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

In a prediction done by using ChemSpider Database (2017),the Soil Adsorption Coefficient i.e Koc value of test chemical was estimated. The adsorption coefficient (Koc) value of test chemical was estimated to be 36113.19 (Log Koc = 4.557) at both pH 5.5 and 7.4, respectively. This Koc value indicates that the test chemical has a very strong sorption to soil and sediment and therefore have negligible migration potential to ground water.

 

Additional soil adsorption coefficient i.e Koc value of test chemical was estimated using the SciFinder database (American Chemical Society (ACS), 2017).The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 21300 at pH range 1-10, respectively (at 25 deg C). This Koc value indicates that the test chemical has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

On the basis of above overall results for test chemical, it can be concluded that the log Koc value of test chemical was estimated to be ranges from 4.2 to 4.55, respectively, indicating that the test chemical has a strong to very strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.