Benzene extraction and cobalt(iii) oxide powder collection for the determination of total selenium in food and biological samples by electrothermal atomic absorption spectrometry using a tungsten furnace

Abstract

Benzene extraction and cobalt(III) oxide powder collection were studied for the determination of total selenium in food and biological samples by electrothermal atomic absorption spectrometry using a tungsten furnace. Selenium was extracted into benzene using hydrochloric acid with the addition of potassium iodide, and cobalt(III) oxide powder was added to the benzene to collect the extracted selenium. The cobalt(III) oxide powder was separated from benzene by vacuum filtration and then suspended in 1 ml of water. Part of the slurry thus obtained was introduced into the tungsten furnace and the determination of selenium performed. As a result, 100% recoveries of selenium(IV) and selenium(VI) were obtained for 8 M hydrochloric acid containing 1.0 M potassium iodide. The relative standard deviation using the slurry at the 0.20 mg l–1 selenium level with the proposed method was 3.4% (n = 6). The calibration curve was linear up to 0.50 mg l–1 (5.0 ng per 10 µl) and the detection limit (3σ) was 16.0 µg l–1 (0.16 ng per 10 µl). The proposed method was applied to food and biological samples.