Improved method of sampling and determination of traces of hydrogen sulphide

A sensitive spectrophotometric method for the determination of traces of hydrogen sulphide in environmental samples, after fixation as zinc sulphide, is reported. The method is based on the reaction between iodate and sulphide in the presence of excess of chloride ions. The resulting iodine chloride complex is ion-paired with Pyronine G and the product is extracted into benzene. The colour system obeys Beer's law over the range of 0.05–0.6 g of hydrogen sulphide. The coefficient of variation is 6.3% for 10 determinations of 0.3 g of hydrogen sulphide. The suitability of the method for monitoring hydrogen sulphide in atmospheric air in the vicinity of possible sources such as a sewage treatment plant and in wastewater has been evaluated.