Extraction, purification, and determination by HPLC of quercetin in some Italian wines
In this paper, we report a simple method for the determination of quercetin, a typical antioxidant compound ubiquitously present in vegetable food products including grapes and wine. To this aim, 12 Italian wines were analyzed and the amount of quercetin was determined by high-performance liquid chromatography with ultraviolet detector. To reduce the interferences, a minimal sample preparation was performed on solid phase cartridge, then the samples were eluted through a narrow bore C18 column under gradient elution in less than 25 min. Nine wines were red and three white. The amount of quercetin ranged from 0.5 to 4.3 mg L−1. The method was evaluated in terms of reproducibility, linearity, recovery, and limits of detection and quantification, and it resulted relatively fast, economical, and suitable for those laboratories involved in routine analysis. In addition, the possibility to determine the content of quercetin derivates, as free quercetin, after acidic hydrolysis was investigated. Despite the limited number of analyzed samples, the results from this explorative study are in agreement to those from other surveys. Moreover, due to the problems arising from hydrolysis, further research are needed for determining each single quercetin derivate in wine, in order to better characterize its active compounds