Colorimetric Determination of micro amounts of Sulfate in Rainwater by Reagents of 2-Aminoperimedine coupled to Dinitrosulfonazo III

Abstract

An indirect method involving the combined use of 2-aminoperimidine and dinitrosulfonazo III was studied for the determination of sulfate ion in rainwater.
The advantages obtained with the proposed method are as follows.
This method was found to be 50 times as sensitive as the widely used barium chloranilate method which has been. The lower limits of determination was 0.2 ppm for rainwater.
The calibration curve obtained by the present method was linear for the range of 0 to 20 ppm, showing a satisfactory reproducibility as evidenced by the coefficient of variation of 3% found for repeated experiments.
No noticeable interference by foreign ions at concentrations of 10 to 20ppm was observed, and the color stability was satisfactory.
The sulfate ion concentrations in rainwater were found to be 3.4 to 17 ppm by the present method, showing a good agreement with the results obtained by the nephelometric method using barium chloride, one of the conventional methods for determining sulfate ion.