Comparison of methods for determination of polyphenols in wine by HPLC-UV/VIS, LC/MS/MS and spectrophotometry

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.Glede na kemijsko sestavo delimo fenolne antioksidante na flavonoide in neflavonoide. Glede na taninski značaj jih delimo na taninske in netaninske fenole. Omenjene fenolne komponente so odgovorne za visok antioksidativni potencial vina. Primerjali smo določanje galne kisline, katehina, epikatehina, resveratrola, kvercetina dihidrobenzojske kisline, sinapinske kisline, vanilinske kisline, kavne kisline, klorogenske kisline, ferulne kisline, elaginske kisline, p-kumarne kisline in kaftarjeve kisline v številnih vzorcih vin z uporabo dveh metod tekočinske kromatografije z UV/VIS detekcijo in z masnospektrometrično detekcijo (LC/MS/MS). Uporabili smo konvencionalno spektrofotometrično metodo s Folin-Ciocalteu-jevim reagentom za določanje vsebnosti skupnih fenolov in rezultate primerjali z rezultati kromatografskih metod. Kljub zadovoljivim korelacijam smo ugotovili statistično signifikantne razlike med HPLC-UV/VIS in LC/MS/MS, kar je lahko posledica koelucije, ki je z UV/VIS detektorjem ne zaznamo. Primerjava med rezultati, dobljenimi s spektrofotometrično metodo in vsoto fenolnih komponent, določanih z LC/MS/MS je pokazala različne korelacijske premice za rdeča, rosé in bela vina