Determination of low concentrations of dibenzyl sulfoxide in aqueous solutions

Abstract

A spectrophotometric method was developed for the determination of low concentrations of sulfoxide in water, relying on the formation of a leuco-compound from the reaction of L-tryptophan with p-dimethylaminobenzaldehyde and its oxidation by sulfoxide in hydrochloric acid medium. The optimum conditions for the determination were found by using the simplex method. The calibration curve, measured at 620 nm, is linear up to the sulfoxide concentration 7.5 . 10^-5 mol l^-1 (i.e. 17.3 ppm), the limit of determination is 0.1 ppm, the reproducibility, expressed as the relative standard deviation (for n = 6) is 3-4%. Oxidants interfere with the determination. Nitrates can be removed by means of a strongly basic anion exchanger in the chloride form. Mixture water-acetone (6 + 1) passing with a low flow rate should be applied to the elution of the partly sorbed sulfoxide.