A hydride generation atomic fluorescence spectrometric procedure for selenium determination after flow injection on-line co-precipitate preconcentration

A flow injection (FI) on-line preconcentration procedure for ultra-trace inorganic selenium was developed with detection by atomic fluorescence spectrometry. Selenium (IV) is co-precipitated with lanthanum hydroxide and collected on a PTFE beads packed column, the precipitate is afterwards dissolved with hydrochloric acid followed by hydride generation with reduction by tetrahydroborate. A thorough scrutiny was made for chemical variables and FI parameters. With a sampling volume of 3.4 ml, quantitative retention of selenium (IV) was obtained, along with an enrichment factor of 11 and a sampling frequency of 38 h(-1). The detection limit, defined as 3 times the blank standard deviation (3 sigma), was 5 ng l(-1). The precision was characterized by a RSD value of 1.2% (at the 0.5 mu g l(-1) level, n = 11). The enrichment factor was further enhanced to 20 along with a detection limit of 3 ng l(-1), with a sample loading volume of 6.8 ml. The procedure was validated with certified reference materials and biological samples. It was also applied to the speciation of inorganic selenium in surface waters. (c) 2005 Elsevier B.V. All rights reserved.