Determination of Inorganic Selenium in Rice by Atomic Fluorescence Spectrometry with Solid Phase Extraction

A method was established for determination of inorganic selenium in rice by atomic fluorescence spectrometry with solid phase extraction. The rice sample of 0.5 g was extracted with 20 mL of water. After centrifugation, 5 g·L^-1 sodium hydroxide solution was added into the supernatant solution to adjust pH to 4-7. The extract obtained by filtration was passing through solid phase extraction with SAX strong anion exchange column, and the eluate of 10 mL was collected in order to separate inorganic selenium. Then the content of inorganic selenium in rice was determined by atomic fluorescence spectrometry. As shown by the results, linear relationship between values of mass concentration of inorganic selenium and its respective fluorescence intensity was kept within 10 μg·L^-1, with detection limit (3s) of 2.52 μg·kg^-1. Test for recovery was made by standard addition method, giving results in the range of 90.3%-98.2%, with RSDs (n=6) of the determined values ranged from 9.9% to 19%.