On-line determination of sulphite in brine by flow-injection analysis

A spectrophotometric flow-injection procedure for the determination of sulphite in aqueous media over the range 0.5-20 mg 1-1 is described. The reagent used was the organic disulphide 5,5′-dithiobis(2-nitrobenzoic acid). Results are presented for a laboratory-based method for sulphite in water and a potential on-line method for sulphite in high ionic strength potassium chloride brine. The general attractions of flow-injection-based monitors for the on-line analysis of liquid process streams are also discussed.