A kinetic method for the determination of selenium(IV) in ethanol solution

Abstract

A kinetic method for the determination of selenium(IV) in ethanol solution is proposed. The method is based on the action of selenium(IV) upon the oxidation of Nile Blue A by hydrogen peroxide in the presence of phosphate buffer (pH 10.8). The reaction rate was followed spectrophotometrically at 637.5 nm. It was established that the action of selenium(IV) on the indicator reaction is maximal with a 0.25% ethanol solution. The kinetic expression for the reaction in the presence and absence of selenium(IV) are postulated. Optimal experimental conditions for the determination of selenium(IV) were established and selenium(IV) was determined in concentrations from 0.95×10 -2 to 12.6×10 -2 ng cm -3 , with a relative standard deviation of 5.2% A lower detection limit (1.6×10 -3 ng cm -3 ) and higher selectivity compared to the determination in aqueous solution are obtained. The method was applied for the determination of selenium(IV) in mineral water.