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 X-ray 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 cm3 and the preconcentration factor can be calculated to be 104.