Gas chromatography analysis of varietal thiols in wines with application of derivatization and stable isotope dilution analysis

Razvijene su metode analize sortnih tiola u vinu. Sortni tioli i njihovi derivati akumulirani su ekstrakcijom na čvrstoj fazi i mikroekstrakcijom na čvrstoj fazi iz para iznad otopine. Optimirani su uvjeti derivatizacije etil-propiolatom i ekstrakcije sortnih tiola. Kalibracija je provedena tehnikom dodatka standarda u kombinaciji s tehnikom izotopnog razrjeđenja deuteriranim izotopomerima kao unutarnjim standardima. Kvalitativna i kvantitativna analiza sortnih tiola provedena je vezanim sustavom plinski kromatograf i tandemni spektrometar masa s trostrukim kvadrupolom uz praćenje višestrukih reakcija. Analiti su kvantificirani i detektorom kemiluminescencije sumpora te detektirani vezanim sustavom sveobuhvatne plinske kromatografije - spektrometrije masa. Po prvi puta određene su masene koncentracije sortnih tiola u hrvatskim vinima sorte Sauvignon bijeli, koje su bile u rasponu od 6,1 ng L-1 do 135,0 ng L-1. Istražen je utjecaj dodatka antioksidansa prilikom vinifikacije na koncentraciju sortnih tiola i očuvanje arome vina. Zastupljenost sortnih tiola bila je najviša kod tretmana vina kombinacijom kalijeva metabisulfita, askorbinske kiseline i galotanina, dok su najniže koncentracije izmjerene u vinima sumporenima dvostruko nižom dozom kalijeva metabisulfita u odnosu na kontrolu. Kombinacija antioksidansa potvrđuje sinergistički utjecaj askorbinske kiseline i sumporenja vina na očuvanje sortnih tiola radi sprječavanja reakcije tiola s kinonima.Methods for the analysis of varietal thiols in wines were developed and validated. Optimization conditions for the derivatization and extraction of varietal thiols was performed. Varietal thiols or derivatives thereof were extracted by solid-phase extraction or headspace solid-phase microextraction. Calibration was performed by standard addition combined with stable isotope dilution analysis with internal standards. The developed method was used for quantification of varietal thiols in wines by gas chromatography – tandem mass spectrometry with triple quadrupole and multiple reaction monitoring, by gas chromatography – sulfur chemiluminescence detector and for detection by comprehensive gas chromatography – mass spectrometry. For the first time, the mass concentration of varietal thiols in Croatian Sauvignon Blanc wines was determined, ranging from 6,1 ng L-1 to 135,0 ng L-1. The influence of addition of various antioxidants during the vinification step on the preservation of varietal thiols was investigated. The concentrations of thiols were highest in wines treated with a blend of potassium metabisulfite, ascorbic acid and gallotannins, while being lowest for the 50 % reduced sulfurization treatment. Synergistic effect of ascorbic acid and wine sulfurization on preservation of varietal thiols and inhibition of reaction with quinones was thereby confirmed