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Adsorption / desorption

KOCWIN model of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 10 L/kg (log Koc=1) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a negligble sorption to soil and sediment and therefore have rapid migration potential to ground water.

Additional information

Adsorption / desorption

Various predicted data of the test chemical and supporting weight of evidence studies for its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In aprediction done using theKOCWIN Programof Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical. The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 10 L/kg (log Koc=1) by means of MCI method (at 25 deg C). This Koc value indicates that the test chemical has a negligble sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using Adsorption Coefficient module program as Koc 10 (logKoc = 1) at pH range 1-14, respectively (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)). The logKoc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

In an another 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 1 (Log Koc = 0) at both pH 5.5 and 7.4, respectively. This Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

Additional soil adsorption coefficient i.e Koc value of test chemicalwas estimated using the SciFinder database (2017).The soil adsorption coefficient i.e Koc value of test chemical was estimated to be 1 (logKoc = 0) at pH range 1-10, respectively (at 25 deg C). This Koc value indicates that the test chemical has a negligble sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the adsorption coefficient i.e KOC for test chemical was estimated to be 46.8 L/kg (log Koc = 1.67).The predicted KOC result based on the 5 OECD principles. This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

In a supporting weight of evidence study from study report (2018) for the test chemical, 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 4 mg of test item and diluted with ACN up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.8. 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 were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-

Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Phenol, N,Ndimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.850± 0.006 at 25°C. This log Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

For the test chemical, 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 (Experimental study report, 2018). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 5.4. 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 were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, 4-chloroaniline, 4-methylaniline(p-Tolouidine), N-methylaniline, ptoluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4 -Nitrobenzamide, 1 -naphthylamine, 1 -naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, Pentachlorophenol, Phenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, N-methylbenzamide, Benzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.430 ± 0.002 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid 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 evaluated to be ranges from 0 to 1.85, respectively, indicating that the test chemicalhas a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.