Competing ligand exchange-solid phase extraction method of polyphenols from wine

Abstract

A simple and efficient solid phase extraction technique by a ligand-exchange scheme using functionalized silica nanocomposites has been developed and optimized for the extraction of phenolic compounds from wine. Five polyphenolic compounds - naringin, rutin, p-coumaric acid, quercetin, genistein from untreated wine samples were pre-concentrated and cleaned on adsorbent with covalently immobilized fragments of phosphonic acid – APA covered with Fe3+ ions – Fe/APA The cartridge was conditioned with 5 mL of methanol and equilibrated with 5 mL of 10% (v/v) aqueous MeOH. Co-extracted ballast substances were rinsed from the sorbent with 5 mL of 10% (v/v) aqueous MeOH. Retained phenolic compounds were selectively eluted with 1% formic acid in MeOH. A mobile phase gradient containing 0.1% formic acid and acetonitrile was used for the final baseline chromatographic separation on an RP C18 column. Limits of detection are in the range of 2.2 to 3.9 mg L−1. The method was applied to quantify five phenolic compounds in red and white wine samples.