Response surfaces for the determination of arsenic(III) by hydride generation atomic absorption spectrometry and flow injection

Abstract

The sensitivity of a flow injection hydride generation atomic absorption system for dissolved arsenite is reported as a function of pH and sodium tetrahydroborate concentration for several common buffers. The buffers considered are acetate, formate, propanoate, butanoate, citrate, phosphate and hydrochloric acid. For the acetate buffer, it was found that the response did not reach a plateau at low pH, but rather passed through a maximum around pH 6. This ‘ridge’ in the response surface was found to be more pronounced for lower tetrahydroborate concentrations, and a similar effect was observed to varying degrees for all of the organic buffers. The effect was most pronounced for propanoic acid. Response surfaces were obtained with an automated continuous-flow apparatus under computer control and an efficient experimental design based on continuous variations. The instrumentation and software are described.