Absorptiometric determination of trace amounts of sulphide ion in water

Abstract

A sensitive and rapid method is described for the determination of minimal concentrations of soluble sulphide in water. It is based on the reductionof iron(III) to iron(II) by sulphide at pH 3 in the presence of 1,10-phenanthroline reagent, forming the orange-red complex[(C₁₂H₈N₂)₃Fe]²⁺. The method is subject to some interferences, which fortunately are not usually present in water supplies. Interferences of many acidic and basic radicals can be successfully overcome by recovery of hydrogen sulphide by steam distillation from the samples acidified with sulphuric acid. Down to 0·5 µg or a concentration of 33 µg l^–1 of sulphide, if 15 ml of sample are available, can be detected by the method.