Optimization of supramolecular solvent microextraction prior to graphite furnace atomic absorption spectrometry for total selenium determination in food and environmental samples

In this work, two formats of supramolecular solvent microextraction have been made up of (i) inverted hexagonal aggregates of 1-octanol (rod-like micelle) and (ii) reverse micelles of octanoic acid in tetrahydrofuran (THF):water coupled with graphite-furnace atomic absorption spectroscopy (GF-AAS) were compared. Se(IV) was combined with ammonium pyrrolidine dithiocarbamate (APDC) to obtain hydrophobic complex and extracted to supramolecular solvent phase. The effective parameters on the extraction efficiency were studied and optimized utilizing two different optimization methods: one variable at a time (OVAT) and box-behnken design (BBD). Under the optimum conditions (rod-like micelle; pH = 2; volume of 1-octanol, 125 μL; volume of THF, 1.4 mL; concentration of APDC, 25 ppm), the limit of detection of the method was 0.1 μg L− 1 and the repeatability of the proposed method, expressed as relative deviation, was 4.3%. Linearity was found to be in the range of 0.4-100 μg L− 1 and under the optimum conditions, the enhancement factor was 58. Optimized method was applied to water, urine, cosmetic (including skin cream, sunblock and perfume) and food samples (including garlic, mint and tea) for determination of total selenium.