Size exclusion coupled to reversed-phase líquid chromatography for the characterization of cranberry products

Abstract

A combination of solvent extraction, size exclusion purification and reversed-phase liquid chromatography with UV absorption and fluorescence detection was here used for the determination of flavan-3-ols and related oligomeric compounds in cranberry products. The method relied on robust, simple and inexpensive instrumental equipment present in most of routine analytical laboratories. Sample extracts in methanol/water/hydrochloric acid solution (60:39:1, v:v:v) were subjected to sizeexclusion chromatography (SEC) using Sephadex LH-20 as the sorbent to separate simple phenolic and oligomeric components. As a novel aspect of this work, the implementation of the SEC process in a reusable packed column was practically and economically highly advantageous. Fractions were analyzed by reversed-phase chromatography using a C18 core-shell analytical column and 0.1% formic acid aqueous solution and methanol as the components of the mobile phase. Chromatograms were recorded by UV absorption spectroscopy at 280 nm and by fluorescence spectroscopy at lex 280 nm / lem 347 nm. The method was applied to the determination of flavan-3-ols in various cranberry samples. Catechin, epicatechin and procyanidins A2 and B2 were found in different amounts depending on the cranberry varieties.