Automated determination of sulphide by gas-phase molecular absorption spectrometry

Abstract

An automated method for the determination of sulphide in solution that involves the interfacing of an automatic sampler, a proportioning pump and a gas–liquid separator to an atomic absorption spectrometer is described. Sulphide ions react with 3 mol dm^–3 hydrochloric acid and the released hydrogen sulphide is swept into a gas–liquid separator by an air stream. The absorbance was measured at 200 nm using a deuterium hollow cathode lamp. The method is relatively free from interference with a detection limit for sulphide of 0.06 µg ml^–1 and relative standard deviations of 1.4–3.3% for repeated analyses. The calibration graph is linear up to 100 µg ml^–1 of sulphide. Twenty samples can be analysed in 1 h. The method has been applied to the determination of sulphate-sulphur in plants.