Pre-concentration and determination of aquatic sulphide by visible spectrophotometry

Abstract

The concentration of sulphide in aqueous environmental samples was determined by first pre-concentrating the samples on a cadmium(II)-exchanged zeolite sorbent, followed by conversion to methylene blue. Sulphide was finally quantified by visible spectrophotometry. The various parameters affecting the sulphide recovery of this method, such as flow-rate, zeolite column bed height, sample size, sample volume and aspiration time, were investigated. A comparison of this method with the currently accepted sulphide spectrophotometric method indicated that the pre-concentration technique yields a lower limit of detection, a greater certainty of results and the highest sensitivity. The application of the standard additions technique as a means to circumvent potential sample matrix problems in aqueous samples is also discussed.