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Adsorption / desorption

KOCWIN model (v2.00) of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical (+)-Neomenthol (CAS No. 2216 -52 -6). The soil adsorption coefficient i.e Koc value of (+)-Neomenthol was estimated to be 88.15 L/kg (log Koc=1.9452) by means of MCI method (at 25 deg C). This Koc value indicates that the substance (+)-Neomenthol has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Adsorption / desorption

Various predicted data for the target compound (+)-Neomenthol (CAS No. 2216-52-6) and supporting weight of evidence study for its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In aprediction done using theKOCWIN Program(v2.00) of Estimation Programs Interface was used to predict the soil adsorption coefficient i.e Koc value of test chemical (+)-Neomenthol (CAS No. 2216 -52 -6). The soil adsorption coefficient i.e Koc value of (+)-Neomenthol was estimated to be 88.15 L/kg (log Koc=1.9452) by means of MCI method (at 25 deg C). This Koc value indicates that the substance (+)-Neomenthol has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test substance (+)-Neomenthol (CAS no. 2216 -52 -6) was estimated using Adsorption Coefficient module program as Koc 1318, 1317, 1311 and 1255  at pH range 1-11, 12, 13 and 14, respectively (logKoc = 3.1 ± 1.0) (ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017)). The log Koc value indicates that the test substance (+)-Neomenthol has a moderate sorption to soil and therefore have slow migration potential to groundwater.

 

Additional soil adsorption coefficient i.e Koc value of test chemicaltest chemical (+)-Neomenthol (CAS No. 2216 -52 -6)was estimated using the SciFinder database (2017).The soil adsorption coefficient i.e Koc value of (+)-Neomenthol was estimated to be 1340 at pH range 1-10, respectively (logKoc = 3.127) (at 25 deg C). The logKoc value indicates that the substance (+)-Neomenthol has a moderate sorption to soil and sediment and therefore have slow 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 substance (+)-Neomenthol was estimated to be 307 L/kg (log Koc = 2.487).The predicted KOC result based on the 5 OECD principles. This Koc value indicates that the substance (+)-Neomenthol has a moderate sorption to soil and sediment and therefore have slow migration potential to ground water.

 

In a supporting weight of evidence study from experimental study report (2018) for the test item,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 pipetting 4 microliter of test item and diluted with Methanol up to 10 ml. Thus, the test solution concentration was 356 mg/l. The pH of test substance was 6.2. 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 functional similarity with the test substance and calibration graph prepared. The reference substances were Benzamide, Nitrobenzene, 4- Nitrobenzamide, N,N-dimethylbenzamide, N-methylbenzamide, 2 - nitrophenol having Koc value ranging from 1.239 to 2.47. The Log Koc value of test chemical was determined to be 1.805 dimensionless at 25°C. This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore has moderate migration potential to ground water.

 

For the test chemical,adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical (HSDB, 2017). The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test substance was estimated to be 88 dimensionless (Log Koc = 1.944). This Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

On the basis of above overall results for target chemical (+)-Neomenthol (from modelling databases,2017), it can be concluded that the Koc value of test substance (+)-Neomenthol was estimated to be ranges from 307 to 1340, respectively, indicating that the test chemical (+)-Neomenthol has a low to moderate sorption to soil and sediment and therefore have moderate to slow migration potential to ground water.