Comparative study of the determination of peroxomonosulfate, in the presence of other oxidants, by capillary zone electrophoresis, ion chromatography, and photometry

Several methods for quantitative determination of peroxomonosulfate in dete rgents, in the presence of other oxidants, have been investigated. The phot ometric technique applied was based on the well-known starchiodine reaction . The oxidizing agent was quantified by determining the amount of iodine pr oduced. The influence of other oxidants present was examined. Ion analysis was performed by capillary zone electrophoresis (CZE) and ion chromatograph y (IC). Because peroxomonosulfate in detergents is always accompanied by su lfate, the main goal was to separate the sulfur species without causing the decomposition of the unstable peroxomonosulfate ion. The sulfur species co uld be separated within less than 4 min by CZE with a pyromellitic acid ele ctrolyte at pH 3.5 to 5.0. Sulfate and peroxomonosulfate were separated by IC within 11 min by use of a phthalic acid mobile phase at pH 3.0. The pero xomonosulfate content was determined by calibration. The calibration plot w as linear from 5 to 50 mug mL(-1) SO52- for IC and from 7.3 to 182.3 mug mL (-1) SO52- (corresponding to 20 to 500 mug mL(-1) triple salt) for CZE.