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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 648 L/kg (log Koc= 2.81) by means of MCI method at 25 °C. This Koc value indicates that the test chemical has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

Additional information

Adsorption / desorption

Various studies predicted have been conducted for test chemical and experimental study was reviewed for its structurally similar read across chemical and their results are summarized below. 

 

In first study the 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 648 L/kg (log Koc= 2.81) by means of MCI method at 25 °C.

 

In another study the Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using ChemSpider Database. The adsorption coefficient (Koc) value of test chemical was estimated to be 143.46 (Log Koc = 2.156) at pH 5.5 and 143.48 (Log Koc = 2.156) at pH 7.4.

 

In last 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 solvents. A test chemical solution was prepared by accurately weighing 4 mg of test chemical and diluted with Methanol up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 7.15. 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 chosen according to functional similarity with the test substance and calibration graph prepared. The reference substances were 2 - nitrophenol, Nitrobenzene, 4-Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, Benzamide having Koc value ranging from 1.239 to 2.47. The Log Koc value of test chemical was determined to be 1.8124 ± 0.002 dimensionless at 25°C.

 

By considering results of all the studies mentioned above the Log koc value of test chemical was determined to be in range of 1.8 to 2.81 dimensionless. This range log Koc value indicates that test substance has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.