Determination of free molecular phenolics and catechins in wine by solid phase extraction on polymeric cartridges and liquid chromatography with diode array detection

The use of HLB Oasis polymeric cartridges to extract phenolic acids and aldehydes from red wines has been assayed and compared with the combination of ODS and SAX cartridges. The recoveries on the polymeric cartridges resulted to be notably higher with good precisions. The best operation conditions (cartridge conditioning, sample volume, clean-up and elution) for these latter were selected by experiments carried out on a synthetic wine sample spiked with 14 compounds and on red wine samples. A matrix-matched calibration was advisable to reduce the influence of the matrix in the quantification of the analytes as it was verified from the application of standard addition calibrations on several wine samples. Determination of the analytes in the extracts was performed by reversed-phase HPLC using mobile-phase and flow gradients and detection at 250, 280 and 340 nm.