HG-AAS Deterimination of Selenium in Astragalus

The sample of astragalus was digested with HNO3 and H2O2, and the contents of total selenium, inorganic selenium and organic selenium were determined by HG-AAS. Hydride of Se ion was generated by reacting with 15 g·L-1 KBH4-3 g·L-1 NaOH solution. Flow-rate of 240 mL·min-1 for carrier gas was taken in the analysis. Linear relationship between values of absorbance and mass concentration of Se found was in the range within 60 μg·L-1, with detection limit (3σ) of 0.21 μg·L-1. The proposed method was applied to the determination of Se in astragalus, giving values of 105 μg·g-1 for total Se, 15 μg·g-1 for Se(Ⅳ), 9 μg·g-1 for Se(Ⅵ) and 81 μg·g-1 for organic Se. It was found that the main species of Se in astragalus was organic Se, amounting to 77% of the total Se.