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Adsorption/desorption

KOCWIN model (v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical

1 -[(2,4 -dimethylphenyl)diazenyl]-2-naphthol (CAS No. 3118 -97 -6). The estimated soil adsorption coefficient i.e Koc value of 1 - (2, 4 -dimethylphenylazo)-2 -naphthol was estimated to be 139900 L/kg (log Koc=5.1457)  by means of MCI method (at 25 deg C). This Koc value indicates that the substance 1 -[(2,4 -dimethylphenyl)diazenyl]-2 -naphthol has a very strong sorption  to soil and sediment and therefore have negligible migration potential to ground water.

Additional information

Adsorption/desorption

Various predicted data for the target compound1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol(CAS No. 3118-97-6) and the supporting weight of evidence studies for its 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 (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical 1 -[(2,4 -dimethylphenyl)diazenyl]-2-naphthol (CAS No. 3118 -97 -6). The estimated soil adsorption coefficient i.e Koc value of 1 - (2, 4 -dimethylphenylazo)-2 -naphthol was estimated to be 139900 L/kg (log Koc=5.1457)  by means of MCI method (at 25 deg C). This Koc value indicates that the substance 1 -[(2,4 -dimethylphenyl)diazenyl]-2 -naphthol has a very strong sorption  to soil and sediment and therefore have negligible migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS no. 3118 -97 -6) was estimated using Adsorption Coefficient module (v12.1.0.50374) program as Koc approx. 15192 at pH range 0-8, Koc as 15191, 15187, 15146, 14746, 11667 and 3784 at pH 9.0, 10.0, 11.0, 12.0, 13.0 and 14.0, respectively (log Koc value ranges from  3.6 ± 1.0 to 4.2 ± 1.0)(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017). This Koc value indicates that the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol has a strong sorption to soil and therefore have negligible to slow migration potential to groundwater.

 

Adsorption study from authoritative database (SRC PhysProp database, 2017) was conducted for estimating the adsorption coefficient (Koc) value of test chemical 1- (2, 4-dimethylphenylazo)-2-naphthol (CAS no. 3118-97-6). The adsorption coefficient (Koc) value of test substance 1- (2, 4-dimethylphenylazo)-2-naphthol was determined to be 28575 (log Koc = 4.455). This Koc value indicates that the substance 1- (2, 4-dimethylphenylazo)-2-naphthol has a very strong sorption to soil and sediment and therefore have negligible 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 substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS no. 3118 -97 -6) was estimated. The adsorption coefficient (Koc) value of test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol was estimated to be 19891.39 at pH 5.5 and 19891.36 at pH 7.4, respectively (Log Koc = 4.298). This Koc value indicates that the substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to groundwater.

 

Additional soil adsorption coefficient i.e Koc value of test chemical1 -[(2,4 -dimethylphenyl)diazenyl]-2 -naphthol (CAS No. 3118 -97 -6)was estimated using the SciFinder database (American Chemical Society (ACS), 2017).The estimated soil adsorption coefficient i.e Koc value of 1 -[(2,4 -dimethylphenyl)diazenyl]-2 -naphthol was estimated to be 22600 (log Koc =  4.354) (at 25 deg C). This Koc value indicates that the test substance 1 -[(2,4 -dimethylphenyl)diazenyl]-2 -naphthol has a strong sorption to soil and therefore have negligible to slow migration potential to groundwater.

 

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 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol (CAS no. 3118 -97 -6) was estimated to be 4770 L/kg (log Koc = 3.678) .The predicted KOC result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol has a strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

In a supporting study for the read across chemical 1-(phenyldiazenyl)-2-naphthol (CAS no. 842-07-9), adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 1-(phenyldiazenyl)-2-naphthol (SRC PhysProp Database, 2017). The adsorption coefficient (Koc) value of substance 1-(phenyldiazenyl)-2-naphthol was determined to be 3794.7 (log Koc = 3.579). This Koc value indicates that the substance 1-(phenyldiazenyl)-2-naphthol hasa strong sorption to soil and sediment and therefore have negligible to slow migration potential to ground water.

 

For the another read across chemical 1-[(2,5-dimethoxyphenyl)diazenyl]-2-naphthol (CAS no. 6358 -53 -8) from authoritative database (HSDB, 2017), soil adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 1 -[(2,5 -dimethoxyphenyl)diazenyl]-2 -naphthol. The adsorption coefficient (Koc) value was calculated using a structure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of 1 -[(2,5 -dimethoxyphenyl)diazenyl]-2 -naphthol was determined to be 23000 (Log Koc = 4.361). This Koc value indicates that the substance 1 -[(2,5 -dimethoxyphenyl)diazenyl]-2 -naphthol has 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 target chemical1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol(from EPI suite, ACD labs, SRC PhysProp database,ChemSpider, SciFinder database and CompTox Chemistry Dashboard,2017) and for its read across substance from SRC PhysProp Database and HSDB, it can be concluded that the Koc value of test substance1-[(2,4-dimethylphenyl)diazenyl]-2-naphthol ranges from4770–139900indicating that the chemical 1-[(2,4-dimethylphenyl)diazenyl]-2-naphtholhas a strong sorption to soil and therefore have negligible to slow migration potential to groundwater.