Comparison of Methods for Determination of Polyphenols in Wine by HPLC-UV/VIS, LC/MS/MS and Spectrophotometry

Vesna Weingerl,^1,* Matija Strlič² and Drago Kočar³

¹ University of Maribor, Faculty of Agriculture and Life sciences, Vrbanska 30, SI-2000 Maribor, Slovenia
² University College London, Centre for Sustainable Heritage, The Bartlett School of Graduate Studies, Gower Street, London WCIE 6BT, UK
³ University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, SI-1000 Ljubljana, Slovenia

* Corresponding author: E-mail: vesna.weingerl@uni-mb.si

Abstract
Phenolic antioxidants are usually grouped into flavonoids and non-flavonoids, according to their structure. With regard to the tannic character, phenolic antioxidants are further subdivided to tannic phenols and non-tannic phenols. Collectively, these compounds contribute to the high antioxidant capacity of wine. In this work, we compare determination of gallic acid, catechin, epicatechin, resveratrol, quercetin, dihydrobenzoic acid, sinapic acid, vanillic acid, caffeic acid, chlorogenic acid, ferullic acid, ellagic acid, p-coumaric acid and caftaric acid in 141 wine samples using two liquid chromatographic methods and detection systems, i.e. with UV detection and mass-spectrometric detection. In addition, we applied the conventional Folin-Ciocalteu spectrophotometric method for determination of the total phenolic content in wine samples and compared the results with those obtained using the chromatographic methods. Despite satisfactory correlations statistically significant differences between HPLC-UV/VIS and LC/MS/MS were established, which could be related to coelution not detectable with UV/VIS detectors. The correlations between results of the spectrophotometric method and sum of LC/MS/MS determinations are not satisfactory and are different for white, red, and rosé wines.

Keywords: Food analysis; wine; antioxidants; chromatography