Microwave digestion of fish tissue for selenium determination by differential pulse polarography

Abstract

In KIO3NH3NH4Cl medium, the selenium complex Se(O)SO2- 3, resulted from the reaction of selenite and sulphite in acid solution, gave a catalytic wave, which was applied to the determination of selenium in fish by differential pulse polarography. The sample was decomposed using the HNO3/H2SO4/H2O2 digestion mixture in a closed PTFE digestion vessel with microwave heating. The detection limit was 0.06 μg/dm3. The calibration curve was linear up to 8 μg/dm3. Selenate present was reduced with hot hydrochloric acid to selenite. The recoveries of the selenite and selenate in two spiked samples investigated ranged from 91 to 104%. The NIES CRM No. 6 mussel was analyzed and the results obtained agreed well with the reference value (reference value: 1.5 μg/g; found: 1.43 ± 0.05 μg/g). The results obtained by differential pulse polarography were in good agreement with those found by hydride generation atomic absorption spectrometry. © 1993.