AUTOMATION OF SAMPLE PREPARATION AS A PRELIMINARY STAGE IN THE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF POLYPHENOLIC COMPOUNDS IN SHERRY WINES

The procedure for automating the method of sample preparation by solid -phase extraction prior to the HPLC analysis of polyphenolic compounds in sherry wine is described. This method consists of two stages, the first being sample preconcentration and cleaning using a C-18 cartridg e and the second fractionation using a SAX anion exchanger. The first direct application of the method, using a semi-flexible robot system, did not produce satisfactory results, thus requiring a series of modif ications and optimization of the variables inherent in the device itse lf. The automated method as modified produced considerable improvement s over the manual method with respect to the recovery and repeatabilit y values obtained with the different polyphenolic species used in its optimization. Subsequent testing of the method with real samples of sh erry wine proved its applicability for tracking the evolution of polyp henolic species in wine.