Determination of selenium in biological materials by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS)

摘要

The selenium (Se) poor environment in the Scandinavian countries focused the interest on the development of an analytical method with high capacity, sensitivity, low limit of detection, including automated wet digestion, automated analysis and computer aided calculation. To facilitate the choice of an appropriate analytical method, procedures for determination in biological materials were discussed. The most frequently used sample-preparation procedures and various analytical techniques were compiled. Recent methods for determination of Se have more or less comparable sensitivity and detection limits. Thus, the choice of method is mainly influenced by economics and practical requirements such as available equipment, type of sample, length of sample series, expected Se-concentrations. Determinations of Se were performed after automated wet digestion using a mixture of HNO3/HClO4 with a home-made equipment from commercially available components used by application of flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) and an electrically heated quartz tube as atomiser. When analysing blank and Se-standard solutions after wet digestion an absorption signal at 196.0 nm was observed, which disturbed Se measurements at low concentrations. For explanation a great number of possible influencing factors were investigated, thus, the light absorption in the quartz tube depending on the gas flow rate and gas composition, and even acidity of carrier-, blank-, and standard solutions, as well as presence of HClO4 in the solutions. When the difference in acidity between carrier-, blank-, and standard-solutions was eliminated, the gas flow stabilised resulting in disappearance of this effect. The main cause of this light absorption was found in construction of the quartz tube adapted to the light path of the Varian instrument used. The final limit of detection was in the range of 0.1-0.3 ng Se/ml measuring solution (0.3 ml injection volume) and was limited by the noise of the equipment. Selenium determinations with FI-HG-AAS were applied to a great number of different kinds of biological materials. In routine work 2080 liver specimens of moose (Alces alces L.) from 14 regions of Sweden were analysed. The results indicated that the moose is useful for monitoring the amount of Se available for wild-grazing animals and confirmed that the Swedish environment is poor in Se.