Highly selective and sensitive fluorescent determination of Fe3+ within alcoholic beverages with 1,5-diphenylcarbazone-functionalized graphene quantum dots
Mauricio Llaver, Santiago D. Barrionuevo, Horacio Troiani, Rodolfo G. Wuilloud, Francisco J. Ibáñez
Abstract
Herein, we report the synthesis of graphene quantum dots (GQDs) functionalized with 1,5-diphenylcarbazone for the selective quantification of Fe in wine, via front-face fluorescence. Crystalline GQDs are obtained via a clean and relatively size-controlled synthesis based on the electrochemical exfoliation from a graphene foam. The product of the synthesis was later functionalized to solely detect Fe3+ amongst various other ions present within the sample. The detection is based on quenching the fluorescence emission from the functionalized nanomaterial in the presence of the analyte, which follows a linear relationship with the concentration of the analyte, consistent with the Stern-Volmer model. Diverse parameters involved in the measurements, including the pH and excitation wavelength, were optimized, giving place to limits of detection (LOD) of 0.014 mg L−1 and 0.11 mg L−1 in waters and white wines, respectively. A soft UV-based digestion and a profound analysis of interferences were key factors to achieve such LODs. Furthermore, front-face fluorescence measurements improved the applicability of the method by avoiding the commonly occurring matrix shielding effects. We believe that the sensitive, selective, and fast detection of Fe3+ within real (i.e.; wine) samples represents a major step forward in the field.