Determination of Sulfate in Environmental Water by Spectrophotometric Flow Injection Analysis

Sulfate ion in environmental water was determined by flow injection analysis using barium-dimethylsulfonazo-III complex as the reagent at a rate of 12 samples per hour. The linearity and sensitivity were investigated using ethanol-or dimethyl sulfoxide (DMSO)-water as solvent, respectively. DMSO-water medium was beneficial in the determination of a low concentration of sulfate below 3 mg l-1. The calibration curve was linear in the range of 0.1-7 mg l-1 with the correlation coefficient of 0.999. The detection limit was 0.1 mg l-1. The relative standard deviation for 10 injections of SO42- (5 mg l-1) was 1.8%. The results of actual sample analysis agreed satisfactorily with those obtained by ion chromatography.