Flow injection-hydride generation atomic absorption spectrometric determination of Se(VI) and Se(IV): utility of a conventionally heated water bath for the on-line reduction of Se(VI) Original Research Article

A simple flow injection manifold coupled to a hydride generation atomic absorption spectrometer has been designed for Se(VI) and Se(IV) determination. On-line reduction of Se(VI) is performed by passing the sample, in 6.8 M hydrochloric acid, through a conventionally heated water bath. Complete conversion into Se(IV) is achieved in about 1 min. Conventional on-line heating has proved to be a good alternative for the fast conversion of Se(VI) into Se(IV). Its performance, in comparison to microwave heating, is discussed. Reaction kinetic parameters have been obtained via on-line experiments for the first time. A comparison with those values already reported is also presented. A limit of detection of 0.05 ng ml−1 (n=10, 3 s) is obtained for both forms, with a precision (relative standard deviation, n=10, 3 s) better than 3%. The sample throughput is 60 samples/h, better than other flow injection systems reported up to date.