Abstract:

A new method was developed for directly determining total Se, inorganic Se and Se(Ⅵ) using slurry sampling-hydride generation atomic fluorescence spectrometry (SS-HGAFS). For total Se determination, samples were extracted with 5 mL of concentrated HCl, followed by SS-HGAFS analysis. Cyclohexane extraction was used for the separation between inorganic Se and organic Se, and total inorganic Se and Se(Ⅵ) dragged into the water phase were determined by SS-HGAFS in concentrated HCl medium in the absence and presence of 5 g/L Na2SO3, respectively. Organic Se could be calculated by the difference between total Se and inorganic Se, and Se(Ⅳ) by difference of the inorganic Se and the Se(Ⅵ). The method detection limit (RSN = 3) was 0.10 μg/L for Se. Mean spike recoveries for total Se, total inorganic Se and Se(Ⅵ) in real samples of wheat flour, rice flour and Se rich salt were between 90.7% and 107%, with a relative standard deviation (RSD) ranging from 0.7% to 1.9%. The proposed method has the characteristics of accuracy, easy operation, rapidity and high sensitivity, and is most suitable for the speciation analysis of selenium in real samples.

Key words: slurry sampling, hydride generation, atomic fluorescence spectrometry, selenium, speciation, flour, selenium rich salt