Determination of Total Selenium in Geochemical Samples by Hydride Generation Atomic Fluorescence Spectrometry with Four Acids Digestion

Hydrochloric acid (2.5 mL), nitric acid (2.5 mL), hydrofluoric acid (2.5 mL) and perchloric acid (5 mL) were used as acid system, and 0.250 0 g of the sample was digested at 110-150 ℃. After digestion, 5 mL of hydrochloric acid as the reductant and 5 mL of 10 g·L^-1 ferric chloride solution as the masking agent were added when it was hot, and the sample solution obtained was diluted to 25 mL with water for test, in which total selenium was determined by hydride generation atomic fluorescence spectrometry. As shown by the results, linear relationship between mass concentration of selenium and its response value was kept within 20.00 μg·L^-1, with detection limit (3s/k) of 0.06 μg·L^-1. The national standard substances of rock, soil and stream sediment were verified, and RSDs of the determined values were ranged from 0.68% to 2.5%, with values of recovery in the range of 94.0%-110%.