Determination and Speciation of Selenium Species in Real Water and Food Samples Using Dispersive Liquid-liquid Microextraction and Electrothermal Atomic Absorption Spectrometry

A new method was developed for the determination and speciation of selenium species in real water and food samples using dispersive liquid-liquid microextraction and electrothermal AAS. Sodium dibenzyldithiocarbamate was used as the complexing agent and THE (tetrahydrofuran) and chloroform as a dispersing and extraction solvent. Excellent quantitative recovery for Se(IV) was obtained at pH 2, while the recovery for Se(VI) was below 14% at the pH ranging from 1-9. Determination of total selenium was performed after Se(VI) was reduced to Se(IV). The concentration of Se(VI) was obtained by calculating the difference between total selenium and Se(IV). The validation of this method was verified by using certified reference materials and good results were obtained. The limit of detection and the preconcentration factor of the described method were found to be 0.97 mu g L-1 and 75, respectively, with the relative standard deviation at <1.4%.