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 determination by hydride generation atomic absorption spectrometry were compared, in which potassium hexacyanoferrate(III) was chosen as a masking agent for eliminating matrix interferences. The results showed that the methods employing HNO3/H2O2, HNO3/K2S2O8/H2O2 and HNO3/H3PO4/H2O2 digestion media were unreliable. However, the decomposition using the digestion media of HNO3/H2SO4/H2O2 enabled adequate digestion of fish tissue and retention of selenium in a state amenable for determination. Therefore, the digestion procedures with HNO3/H2SO4/H2O2 media are proposed for the determination of selenium in fish tissue by hydride generation atomic absorption spectrometry. The recoveries of the spiked samples investigated ranged from 90 to 102%. The result obtained from analyzing the NIES CRM No. 6 mussel was in good agreement with the reference 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 ranged from 0.49 to 2.90 mug/g, and the relative standard deviation for the determination of selenium was less than 8%.