COMPARISON OF 4 MICROWAVE DIGESTION METHODS FOR THE DETERMINATION OF SELENIUM IN FISH TISSUE BY USING HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY

Four microwave digestion methods of fish tissue for selenium determina tion by hydride generation atomic absorption spectrometry were compare d, in which potassium hexacyanoferrate(III) was chosen as a masking ag ent for eliminating matrix interferences. The results showed that the methods employing HNO3/H2O2, HNO3/K2S2O8/H2O2 and HNO3/H3PO4/H2O2 dige stion media were unreliable. However, the decomposition using the dige stion media of HNO3/H2SO4/H2O2 enabled adequate digestion of fish tiss ue and retention of selenium in a state amenable for determination. Th erefore, the digestion procedures with HNO3/H2SO4/H2O2 media are propo sed for the determination of selenium in fish tissue by hydride genera tion atomic absorption spectrometry. The recoveries of the spiked samp les investigated ranged from 90 to 102%. The result obtained from anal yzing the NIES CRM No. 6 mussel was in good agreement with the referen ce value (reference value: 1.5 mug/g; found: 1.45 +/- 0.05 mug/g). The limit of detection for selenium was 0.03 mug/g dry mass for a 100 mg sample. The contents of selenium in local fish species investigated ra nged from 0.49 to 2.90 mug/g, and the relative standard deviation for the determination of selenium was less than 8%.