Determination of micro-amounts of polythionates. Part XI. Spectrophotometric determination of two species of polythionates in their mixtures by cyanolysis and solvent extraction

Abstract

Two species of polythionates, when present in their mixtures, have been determined by solvent extraction and spectrophotometry of the thiocyanate formed by cyanolysis of polythionates in both the absence and presence of copper(II) ions. When 1 mol of polythionate, S_xO₆^2–(where x= 4, 5 or 6) undergoes cyanolysis, x–2 mol of thiocyanate are formed in the presence of copper(II) ions; in the absence of Cu(II), x–3 mol of thiocyanate are formed. Therefore, the value of x in S_xO₆^2– can be evaluated. By using these values, the composition of solutions containing two species of polythionates was calculated. The present method can be applied to the determination of two species of polythionates when mixed in various ratios at a concentration level of micromoles per litre.