DETERMINATION OF MICROQUANTITIES OF THIOSULFATE BY KINETIC METHOD

A new redox indicator reaction between Cu2+, Mn2+ and S2O32- in the pr esence of 2,2'-bicinchoninic acid is investigated. Optimum reaction co nditions are determined. The influence of nonaqueous solvents on the r eaction rate is studied. It is shown that in the presence of acetone t he S2O32- determination limit is lowered 0.005 mu g ml(-1). Random err ors lie within the limits allowable at the determination of microconce ntrations. To raise the sensitivity of the determination of S2O32- in some inorganic salts (KCl, KNO3, CsNO3), this impurity was concentrate d by low-temperature directed crystallisation. Metrologic characterist ics of the developed technique are presented. (C) 1998 Elsevier Scienc e B.V. All rights reserved.