Investigation of a new reaction for the determination of microquantities of sulfite in some inorganic salts

A new redox indicator reaction between Cu2+, Mn2+ and SO2−3 in the presence of 2,2′-bicinchoninic acid is investigated. Optimum reaction conditions are determined. The influence of nonaqueous solvents on the reaction rate is studied. It is shown that in the presence of isopropyl alcohol the sensitivity of sulfite determination increases up to 0.3 μg/ml. Random errors lie within the limits allowable at the determination of microconcentrations. To raise the sensitivity of the determination of sulfite in some inorganic salts (KCl, KNO3, CsNO3), this impurity was concentrated by the method of low-temperature directed crystallization. The metrological characteristics of the developed technique are presented.