Analysis of aged red wine pigments by capillary zone electrophoresis.

Red wines of different ages (1-14 years) were analysed by Capillary zone electrophoresis (CZE). Pigments were separated using a fused silica capillary with an effective length of 56 cm and an internal diameter of 75 cm. Disodium tetraborate at 50 mM with a pH of 9.4 was used as buffer solution with methanol as modifier. Electrophoregrams were recorded at 280, 520 and 599 nm and spectra were measured from 200 to 599 nm using a diode array detector. Several differences in the CZE signals obtained for different aged wines were observed, as well as between red and white wines. The signals of a group of seven peaks increased in mature wines. A decrease in free anthocyanins was also identified in aged wine. The migration times of these compounds corresponded to charge/size ratios higher than those of free anthocyanins, and their spectra suggested combinations of anthocyanins with flavanols or tannins. The global CZE response of these pigmented polyphenolic polymers was linearly correlated with the spectrophotometric determination of polymeric pigments (96%) and age (92%).