Studies on photochemical vapor generation of selenium with germicidal low power ultraviolet mercury lamp

Photochemical vapor generation (photo-CVG) with flow injection - atomic fluorescence spectrometry was investigated for the determination of selenium, using formic and acetic acids as photochemical reagents. Using a germicidal low power ultraviolet mercury-based lamp, emitting both the 185 and 254 nm Hg lines, mild reaction conditions can be achieved in formic acid medium, where optimal sensitivity was obtained, at 0.3-0.5% w/w acid concentrations, whereas the optimal sensitivity could be attained with acetic acid in the range from 12 to 35% w/w. The only volatile Se product identified by gas chromatography-mass spectrometry from formic acid based photo-CVG was selenium carbonyl. A series of dedicated experiments were performed using photo-CVG and pure dimethylselenide in order to identify reaction pathways contributing to the formation of non-volatile selenium species or to the degradation of volatile selenium species. Under the optimized conditions in formic add, using 250 mu L sample volume, the limits of detection and quantification were 0.10 and 035 mu g L-1, respectively. The effect of several interfering species was investigated and the method was tested in the analysis of certified reference materials. (C) 2016 Elsevier B.V. All rights reserved.