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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 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1 -(4 -sulphophenyl)-1H-pyrazole-3 -carboxylic acid (CAS No. 11049 -98 -1). The soil adsorption coefficient i.e Koc value of 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid was estimated to be 11.76 L/kg (log Koc=1.0705) by means of MCI method (at 25 deg C). This Koc value indicates that the substance 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3- carboxylic acid has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Additional information

Adsorption / desorption

Various predicted data for the target compound 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid (CAS No. 10149-98-1) 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 (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1 -(4 -sulphophenyl)-1H-pyrazole-3 -carboxylic acid (CAS No. 11049 -98 -1). The soil adsorption coefficient i.e Koc value of 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid was estimated to be 11.76 L/kg (log Koc=1.0705) by means of MCI method (at 25 deg C).

 

The Soil Adsorption Coefficient i.e Koc value of test substance 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acide (CAS no. 10149 -98 -1) was estimated using Adsorption Coefficient module (v12.1.0.50374) program as Koc 1 (log Koc = 0) at pH range 1-14 respectively(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017).

 

In an another prediction done by using ChemSpider Database (2017),the Soil Adsorption Coefficient i.e Koc value of test substance 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid (CAS no. 10149 -98 -1) was estimated. The adsorption coefficient (Koc) value of test substance 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1 -(4 -sulphophenyl)-1H-pyrazole-3 -carboxylic acid was estimated to be 1 (Log Koc = 0) at pH 5.5 and 7.4, respectively.

 

Additional soil adsorption coefficient i.e Koc value of test chemical4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy) ethyl]sulphonyl]phenyl]azo]-1 -(4 -sulphophenyl)-1H-pyrazole-3 -carboxylic acid (CAS No. 10149 -98 -1)was estimated using the SciFinder database (American Chemical Society (ACS), 2017). The soil adsorption coefficient i.e Koc value of 4,5 -dihydro-5 -oxo-4 -[[4 -[[2 -(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1 -(4 -sulphophenyl)-1H-pyrazole-3 -carboxylic acid was estimated to be 1 (log Koc = 0) (at 25 deg C).

 

In a supporting weight of evidence study from experimental study report (Sustainability Support Services (Europe) AB, Report no. UERL/PC/010-03, 2017) for the read across chemical 3,4-dimethylaniline (CAS no. 12225-21-7),the adsorption coefficient Koc in soil and in sewage sludge of read across chemical aluminum tris(4-{[3-carboxy-5-oxo-1-(4-sulfophenyl)-4,5-dihydro-1H-pyrazol-4-yl]diazenyl}benzenesulfonate) (CAS No. 12225-21-7) 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 weighing 3 mg of test item and diluted with methanol up to 10ml. Thus, the test solution concentration was 300 mg/l. The pH of test substance was 6.71. 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 2-nitrophenol, nitrobenzene, 4-nitrobenzamide, N, N-dimethylbenzamide, N-methylbenzamide and benzamide having Koc value ranging from 1.239 to 2.47. The Log Koc value of test chemical aluminum tris(4 -{[3 -carboxy-5 -oxo-1 -(4 -sulfophenyl)-4,5 -dihydro-1H-pyrazol-4 -yl]diazenyl}benzenesulfonate) was determined to be 0.7040 ± 0.01 at 25°C.

 

On the basis of above overall results for target chemical 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid (from EPI suite, ACD labs,ChemSpider and Scifinder,2017) and for its read across substance from study report (UERL study report, 2017), it can be concluded that the Koc value of test substance 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid ranges from1– 11.76, indicating that the test chemical 4,5-dihydro-5-oxo-4-[[4-[[2-(sulphooxy)ethyl]sulphonyl]phenyl]azo]-1-(4-sulphophenyl)-1H-pyrazole-3-carboxylic acid has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.