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)

A simple how injection manifold coupled to a hydride generation atomic abso rption 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 hy drochloric acid, through a conventionally heated water bath. Complete conve rsion into Se(IV) is achieved in about 1 min. Conventional on-line heating has proved to be a good alternative for the fa st conversion of Se(VI) into Se(IV). Its performance, in comparison to micr owave 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 f orms, with a precision (relative standard deviation, n = 10, 3 s) better th an 3%. The sample throughput is 60 samples/h, better than other flow inject ion systems reported up to date. (C) 2000 Elsevier Science B.V. All rights reserved.