Analysis of pigmented high-molecular-mass grape phenolics using ion-pair, normal-phase high-performance liquid chromatography.

A normal-phase LC method has been developed to analyze high-molecular-mass grape phenolic compounds. Samples are prepared by first isolating phenolics using C18-SPE. The analytical method uses a silica column and gradient elution with mobile phases of methylene chloride, methanol, formic acid and heptanesulfonic acid. This separation enables the analysis of these compounds from grape and wine samples in the presence of anthocyanins without extensive purification. Based on the elution order of proanthocyanidins and anthocyanins, phenolics elute in order of increasing molecular mass. Currently, it is not possible to identify all of the components separated in the chromatogram.