Analytical Sciences

Optimization of a Chemical Modifier in the Determination of Selenium by Graphite Furnace Atomic Absorption Spectrometry and Its Application to Wheat and Wheat Flour Analysis

Viorica ALEXIU* and Luminita VLADESCU**

*Magistra C&C, 9th, Aviator Belghiru Street, 900133, Constanta, Romania
**University of Bucharest, 2-12th, Regina Elisabeta Boulevard, 030018, Bucharest, Romania

A method for the determination of total selenium in wheat and wheat flour using graphite furnace atomic absorption spectrometry (GFAAS) with palladium/ascorbic acid as a chemical modifier was studied. The effects of nickel nitrate, palladium/ascorbic acid, and palladium/magnesium nitrate as chemical modifiers on the sensitivity in the determination of selenite, selenate and selenomethionine by GFAAS were compared. The palladium/ascorbic acid modifier was used for the determination of total selenium in wheat and wheat flour, because the oxidation states of the selenium ion are not important in the determination. The detection limit was estimated to be 1 µg L^-1 (calculated as 3 σ of the blank); the calibration curve was linear for the concentration range 5 - 50 µg L^-1 and the recovery range was 96.66 - 101.80%. The optimal ashing and atomizing temperatures were 1300°C and 2250°C, respectively. The proposed method was successfully applied to the determination of total selenium in wheat and wheat flour.

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