IDENTIFICATION OF FLAVAN-3-OLS AND PROCYANIDINS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND CHEMICAL-REACTION DETECTION

A method for characterizing flavan-3-ols and procyanidins by HPLC sepa ration in connection with on-line UV detection and chemical reaction d etection (CRD) is described. The post-column derivatization of the pol yphenols with 4-dimethylaminocinnamaldehyde in the presence of sulphur ic acid improves the sensitivity as compared to UV detection. The exte nt of improvement strongly depends on the structure of the procyanidin , hence resulting in characteristic absorbance ratios (CRD/UV) for the individual compounds under given reaction conditions. The ratios are further influenced by the solvent composition, by reaction time and by temperature.