Speciation and preconcentration of chromium in real samples by magnetic polythiophene nanoparticle solid-phase extraction (SPE) coupled with microsampling injection - flame atomic absorption spectrometry (FAAS)

Magnetic solid-phase extraction was evaluated using polythiophene nanoparticles (Fe3O4@PTh) as the adsorbent for chromium speciation from water samples and total chromium preconcentration from food, biological, and soil samples. Chromium concentrations were determined by microsample injection system - flame atomic absorption spectrometry (MIS-FAAS). Chromium speciation was achieved with selective adsorption of Cr(III) in the presence of Cr(VI) by Fe3O4@PTh from pH 6.5 to 10.0. Total chromium was preconcentrated after the reduction of Cr(VI) to Cr(III). The linear range, detection limit, enrichment factor, and repeatability of the optimized method for Cr(III) in aqueous solution were 4-60 mu g L-1, 1.3 mu g L-1, 124.7, and 2.2%, respectively. The method was validated by analyzing SPS-WW2 Batch 114, NCS DC 78302 Tibet soil, and LGC7162 strawberry leaves as standard reference materials (SRMs). The results are in good agreement with the certified values. Good recovery, precision, and relative error values were obtained for chromium in real samples by the optimized method.