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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
weight of evidence
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 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 determined using a water solubility and a regression derived equation.
GLP compliance:
no
Type of method:
other: estimation
Media:
soil
Radiolabelling:
no
Analytical monitoring:
no
Key result
Type:
Koc
Value:
0.68 dimensionless
Remarks on result:
other: Log Koc = -0.167
Transformation products:
not specified

According to a classification scheme, the estimated Koc value suggests that chloral is expected to have very high mobility in soil (high mobile).

Validity criteria fulfilled:
not applicable
Conclusions:
The adsorption coefficient Koc) value of test chemical was determined to be 0.68 dimensionless calculated using a water solubility of 8300000 mg/L and 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 water solubility of 8300000 mg/L and regression derived equation. The adsorption coefficient (Koc) value of test chemical was determined to be 0.68 (Log Koc = -0.167). This Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have a rapid migration potential to groundwater.

Description of key information

Adsorption study was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a water solubility of 8300000 mg/L and regression derived equation. The adsorption coefficient (Koc) value of test chemical was determined to be 0.68 (Log Koc = -0.167). This Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have a rapid migration potential to groundwater.

Key value for chemical safety assessment

Koc at 20 °C:
0.68

Additional information

Various predicted data for the test chemical were reviewed for the adsorption end point and their results are summarized as below:

 

In first study the Adsorption experiment was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a water solubility of 8300000 mg/L and regression derived equation. The adsorption coefficient (Koc) value of test chemical was determined to be 0.68 (Log Koc = -0.167). This Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have a rapid migration potential to groundwater.

 

In next study the KOCWIN model (v2.00) of Estimation Programs Interface (EPI Suite, 2020) 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 2.138 L/kg (log Koc=0.33)  by means of MCI method at 25 °C. This Koc value indicates that the test chemical has a negligible sorption to soil and sediment, rapid migration to ground water.

 

In another study the Soil Adsorption Coefficient i.e Koc value of test chemical was estimated using Adsorption Coefficient module (v12.1.0.50374) program as Koc 179 (log Koc = 2.3 ± 1.0). This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration to ground water.

 

Last study was experimental study in this 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 50mg of test chemical and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 6.24. 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 structural similarity with the test substance and calibration graph was prepared. The reference substances were 2- Nitrobenzamide, p – Toluamide, 4 – methyl aniline, Aniline, N – methyl aniline, 2,5 Dichloroaniline having Koc value ranging from 1.45 to 2.58. The Log Koc value of test chemical was determined to be 1.645 ± 0.003 dimensionless 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.

 

On the basis of above results for test chemical it is concluded that the Koc value of test chemical ranges from -0.167 to- 2.3 dimensionless indicating that the test chemical has negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.