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Adsorption/desorption:

The Soil Adsorption Coefficient i.e. Koc value of test chemical 4-[(3-aminobenzoyl)amino]-5-hydroxynaphthalene-1,7-disulphonic acid (CAS No. 70239-77-9) was estimated using EPI suite KOCWIN Program (v2.00) as 2231 L/kg (log Koc= 3.3484) by means of MCI method at 25 deg. C. This log Koc value indicates that test chemical 4-[(3-aminobenzoyl)amino]-5-hydroxynaphthalene-1,7-disulphonic acid has moderate sorption to soil and therefore have slow migration potential to ground water.

Additional information

Adsorption/desorption:

One predicted data study of target chemical 4-[(3-aminobenzoyl)amino]-5-hydroxynaphthalene-1,7-disulphonic acid (CAS No. 70239-77-9) and two experimental studies of its structurally similar red across chemical are summarized below for Adsorption endpoint.

 

In predicted data study the Soil Adsorption Coefficient i.e. Koc value of test chemical 4-[(3-aminobenzoyl)amino]-5-hydroxynaphthalene-1,7-disulphonic acid (CAS No. 70239-77-9) was estimated using Estimation Program Interface (EPI suite, 2017) KOCWIN Program (v2.00) as 2231 L/kg (log Koc= 3.3484) by means of MCI method at 25 deg. C.

 

Next weight of evidence study was experimental study done for read across chemical from journal of J. Environ. Eng. Manage., 17(1), 29-38 (2007) in this study the adsorption of Acid Red 1 on organoclay is dominated by ion exchange process. The Freundlich and Langmuir adsorption isotherm constants of Acid Red 1 on organoclay are as follows: Acid Red 1 adsorption on organoclay the coefficients for fitting are 0.995 < rL2 < 0.997 and 0.573 < rF2 < 0.751. It can be seen that the Langmuir model yields a much better fit than the Freundlich model when the r2 values are compared. The affinity parameter, KL, and its reciprocal indicate that the adsorption capacity of Acid Red 1 on organoclay is highly perceptible to changes in temperature. The Q max values indicate that Acid Red 1 possesses higher adsorption capacity at lower temperature.

 

Last weight of evidence study was also experimental study done for another read across chemical disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate (CAS No. 3567-66-6) from UERL laboratory (2016) in this study the adsorption coefficient Koc in soil and in sewage sludge disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate (CAS No. 3567-66-6) was determined by the Reverse Phase High Performance Liquid Chromatographic method. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Phenol, Aniline, Nitrobenzene, naphthalene, Phenanthrene and DDT were chosen having Koc value ranging from 1.32 to 5.63. The Log Koc value of read across chemical disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate was determined to be 3.679 dimensionless at 25°C. Based on the value of log Koc it is concluded that this read across chemical has strong sorption to soil and sediments and therefore has slow migration potential to ground water.

On the basis of all the study mentioned above it is concluded that test chemical 4-[(3-aminobenzoyl)amino]-5-hydroxynaphthalene-1,7-disulphonic acid (CAS No. 70239-77-9) has moderate to strong sorption to soil and sediment therefore it has slow migration potential to ground water.