Optimization and validation of a methodology to quantify enolones and vanillines in wines by an automated solid phase extraction followed by their analysis through gas chromatography-mass spectrometry

Póster presentado en la XVI Reunión Científica de la Sociedad Española de Cromatografía y Técnicas Afines (SECyTA 2016), celebrada en Sevilla del 2 al 4 de noviembre de 2016.
This paper focuses on the analysis of two groups of molecules in wine, enolones and vanillines. Both types of molecules present a common characteristic, their great polarity. Sotolon, maltol, furaneol and homofuraneol belong to the first group. Their chemical structures present certain similarity among them, which leads to similar physicochemical and olfactory properties. This group of compounds is described with the terms “burnt sugar, candy sugar, caramel and maple”. Sotolon and furaneol are the most powerful aromatic molecules within them, being their odor thresholds estimated in water‐ethanol matrix around 5 μg/L [1, 2]. The other group of molecules, vanillines, contributes to the oak related notes of alcoholic beverages. This work presents an automatized strategy to quantify the following aromatic compounds in wine: maltol, furaneol, homofuraneol, sotolon, vanillin, methyl vanillate, ethyl vanillate and acetovanillone. The development of this strategy implied the use of Gilson system (GX‐ 274 liquid handler). The proposed method is based on a solid phase extraction (SPE) using LiChrolut EN resins (50 mg). Three mL of wine were passed through a LiChrolut EN cartridge. After this, two consecutive washing up steps were applied. The first one consisted of 2mL of an aqueous solution at pH 8.0 containing 1 % of NaHCO3. The second one was 2 mL of pentane containing 5 % (v/v) of dichloromethane. The elution of both kinds of compounds was carried out with 600 μL of dichloromethane with 5% (v/v) of methanol. The extract obtained was injected directly in a gas chromatograph with a quadrupole mass spectrometric detection system (GC‐MS). The method showed good linearity in the range of occurrence for all compounds with a squared correlation coefficient higher than 0.9900, except for the ethyl vanillate that was lower. Matrix effects were not found. The detection limits obtained for all analyzed compounds were lower or equal to 0.7 μg/L. The precision was evaluated in reproducibility terms, obtaining in all cases DSR (%) below 12%. This methodology once optimized and validated was applied to quantify these compounds in a wide set of wines. As a result of these analyses, furaneol and vanillin exhibited odour aroma values, (OAV), higher than the unit in most of the samples.