Speciation of chromium in beverages and seasoning samples by magnetic solid-phase extraction and microsample injection system flame atomic absorption spectrometry

In this research, a magnetic solid phase extraction based on the use of magnetic polyaniline-polythiophene copolymer (Fe3O4@coPANI-PTH) nanoparticles is applied for chromium speciation from water, beverages and seasoning samples followed by microsample injection system-flame atomic absorption spectrometry(MIS-FAAS) analysis. The selective adsorption of Cr(III) in presence of Cr(VI) by Fe3O4@coPANI-PTH in the pH range of 9.0-10.5 was obtained and the total Cr, after reduction of chromium(VI) to chromium(III) by adding 0.5 mL of concentrated H2SO4 and 10 mL of 5% (w/v) hydroxylamine hydrochloride, was determined. The detection limit, enhancement factor, and repeatability of the optimized method for Cr(III) were calculated to be 1.5 µg L-1, 38.5, and 1.78%, respectively. The method was validated by the analysis of TMDW-500 drinking water and LGC7162 Strawberry Leaves as certified reference materials. The relative error for total chromium was found to be lower than 4.6%. Recoveries were obtained quantitatively using this method (≥95%).