Registration Dossier

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Adsorption / desorption

The Soil Adsorption Coefficient i.e Koc value of 1-phenylazo-2-naphthol  was estimated using EPI suite  KOCWIN Program (v2.00) program and the value was reported as Koc 53250 L/kg (log Koc=4.726)  by means of MCI method at 25 deg.C. This Koc value indicates that the substance 1-phenylazo-2-naphthol has a very strong sorption to soil and  sediment and show negligible migration potential to groundwater.

Additional information

Adsorption / desorption

Predicted and experimental data of adsorption endpoint for the target chemical 1-phenylazo-2-naphthol (CAS No. 842-07-9) and its read across chemical were reviewed to summarize as follows:  

 

The Soil Adsorption Coefficient i.e Koc value of 1-phenylazo-2-naphthol  was estimated using EPI suite  KOCWIN Program (v2.00) program and the value was reported as Koc 53250 L/kg (log Koc=4.726)  by means of MCI method at 25 deg.C. This Koc value indicates that the substance 1-phenylazo-2-naphthol has a very strong sorption to soil and sediment and show negligible migration potential to groundwater.

 

Whereas Chemspider - ACD/PhysChem Suite prediction model indicates that the soil adsorption coefficient i.e Koc value of test substance 1-phenylazo-2-naphthol was estimated to be 6358.49  i.e Log Koc= 3.8033 at pH 5.5 and 6358.48  i.e Log Koc=3.8034 at pH 7.4.This Koc value indicates that the substance 1-phenylazo-2-naphthol has a strong sorption to soil and sediment and show negligible to slow migration potential to groundwater.

 

Information for the read across chemical Oil pink (CAS No. 1229-55-6) From HSDB authorative database (2017) indicates the adsorption coefficient (Koc) of substance Oil pink i.e 1-[(2-methoxyphenyl)azo]-2-naphthol as 290000 using a measured log Kow of 7.5 and regression derived equation. This Koc value indicates that oil pink will be immobile in soil.

 

Information for another read across substance 1 -[(2,5 -dimethoxyphenyl)diazenyl]-2-naphthol (CAS No. 6358 -53 -8) from same data source i.e HSDB indicate that using a structure estimation method based on molecular connectivity indices, the Koc of 1 -[(2,5 -dimethoxyphenyl)diazenyl]-2-naphthol can be estimated to be 23000. This Koc value indicates that the substance 1-[(2,5 -dimethoxyphenyl)diazenyl]-2-naphthol has strong sorption to soil and sediment and show negligible to slow migration potential to ground water.

Thus based on the above all studies it is concluded that the test substance 1-phenylazo-2-naphthol (CAS No. 842-07-9) has very strong sorption to soil and sediment.