Graphene-based materials as solid phase extraction sorbent for chromium (VI) determination in red wine

We report a novel and selective method for the preconcentration and determination of Cr(VI) in red wine through their adsorption on a tertiary amine, ALIQUAT 336, a commercial anionic exchanger extractant, widely used for the selective extraction of Cr(VI) over Cr(III). The determinations were made directly on the solid, by Xray fluorescence spectrometry, method and large areas held by the graphene, making them a promising solid sorbent for preconcentration procedures, direct quantification of the analyte in the solid sorbent; there by reducing the number of reagents used thus minimizing handling of the sample. A high preconcentration factor was achieved for a very low volume of sample. The enrichment factor was calculated after considering that the thin film obtained from the 10 mL solution of 1 mg L-1 of Cr(VI) has a real thickness of 0.04 mm and a final diameter of 16.7 mm, so that the volume deposited on the pellet was 0.0088 cm(3) and the preconcentration factor can be calculated to be 10(4).