Pervaporation-flow injection determination of arsenic based on hydride generation and the molybdenum blue reaction

Abstract

A pervaporation-flow injection system for the determination of As(III) by the molybdenum blue method is described. Samples containing As(V) were pretreated with KI and HCl prior to injection to reduce As(V) to As(III). As(III) samples were injected into a 0.5 M HNO3 stream and then mixed with a stream containing 0.5% sodium borohydride. The arsine generated was transported in the pervaporation unit across a semi-permeable membrane into a 1.97×10-3 M I3- acceptor solution where it was oxidised to As(V). The acceptor stream was merged with a reagent stream containing 0.01% SnCl2, 0.1% hydrazine sulfate and 0.5% ammonium molybdate thermostated at 70°C. The concentration of arsenomolybdenum blue..