Solid-phase extraction for sample preparation, in the HPLC analysis of polyphenolic compounds in ''fino'' sherry wine

Wine samples are extremely complex in their content of polyphenolic compounds; this necessitates an initial fractionation prior to their analysis by KPLC, to simplify the chromatograms obtained so that they can be reliably identified and quantified. Solid-phase extraction is one of the appropriate techniques for this purpose. This paper presents the work undertaken to devise a method of fractionating polyphenolic compounds in wine; this comprises a sequence of two stages: first, one of cleaning and preconcentration, using a reversed-phase C18 cartridge, and second, one of fractionation into two groups, acid and neutral polyphenols, using a SAX-type anionic exchanger. Both of these stages have been optimized, using standard solutions, to achieve maximum recovery and reproducibility.