A practical exercise for the determination of As(III) by flow injection hydride generation-atomic absorption spectrometry

A practical exercise is presented for determination of very low amounts (ng/l) of As(III) by flow injection (FI) and hydride generation and atomic absorption spectrometry detection. The exercise is directed towards students at the advanced undergraduate level, and it is intended to be an introduction to procedures of FI, which by relatively uncomplicated equipment provide analysis with excellent performance. With the method presented, it can be shown that assays of As(III) in natural waters can be performed only if an on-line preconcentration step is incorporated into the FI manifold. The method offers a unique illustration of the versatility of the FI approach in sample manipulation to reach low detection limits as well as a demonstration of cleverly exploiting kinetic discrimination schemes for promoting the main reaction and eliminating potential side reactions and interferences.