HG-AFS Determination of Inorganic and Organic Selenium in Seafoods with Sequential Injection

The sample (2.500 0 g) of seafoods was extracted with HCl(1+1) solution 25 mL for 18 h at temperature of 60 ℃. After filtration on defatted cotton, the filtrate was extracted with 5 mL of n-hexane. An aliquot of 4.00 mL of the water phase was taken and the content of inorganic selenium was determined by HG-AFS with sequential injection. Total selenium in the sample was determined in a separate sample by AFS with microwave assisted sample treatment. The difference of total selenium and the inorganic selenium represents the organic selenium. Linear relationship between values of fluorescence intensity and mass concentration of inorganic selenium was kept in the range of 1.00-20.0 μg·L-1, with detection limit (3s) of 0.113 μg·L-1. Tests for recovery and precision were made by standard addition method at the concentration levels of 0.100, 1.00, 2.00 mg·kg-1, giving values of recovery and RSD′s (n=6) in the ranges of 84.8%-93.5% and 1.6%-2.5% respectively.