SOLID-PHASE EXTRACTION FOLLOWED BY DISPERSIVE LIQUID-LIQUID MICROEXTRACTION FOR GAS CHROMATOGRAPHY ACCURATE QUADRUPOLE TIME-OF-FLIGHT TANDEM MASS SPECTROMETRY DETERMINATION OF 3‑ALKYL‑2‑METHOXYPYRAZINES IN WINES

FONTANA, A.; CELA, R.; RODRIGUEZ, I.

Santiago de Compostela

Simposio; 19th International Symposium on Advances in Extraction Technologies; 2017

University of Santiago de Compostela, Center for Research in Environmental Technologies and Galician Institute for Food Quality-Agricultural and Agronomic Research Centre

Alkyl methoxypyrazines (MPs) are aroma active compounds which are transferred from grapes into wines, contributing to various green-herbaceous aroma notes [1]. MPs may be beneficial for wine quality, contributing to the specificity of certain varietals (i.e. Cabernet sauvignon). Although some styles of wines renowned for their MPs levels (e.g. New Zealand style Sauvignon blanc), consumers may reject wines even when MP concentrations are in the low ng L-1 range, due to they can mask other aroma compounds. Considering the relevant organoleptic impact of MPs on wine quality and authenticity at extremely low sensory detection thresholds (˂ 15 ng L-1), highly sensitive analytical methods to quantify MPs at trace levels are necessary. The aim of this work was the development and validation of a method for the accurate identification and quantification of MPs in wines using a sequential combination of SPE, as extraction technique, with DLLME concentration, and final selective determination of target compounds by GC-EI-QTOF-MS/MS. Under optimum conditions, extraction and purification of MPs from wines was carried out simultaneously with a reversed-phase Oasis HLB (200 mg) SPE cartridge, using acetonitrile as elution solvent. Afterwards, the extract was submitted to DLLME procedure. Considering matrix-matched calibration as quantification technique, the overall recoveries of the procedure ranged between 81% and 108% for red and white wine samples spiked at 5 ng L-1. Relative standard deviations of the above data stayed below 11% and the limits of quantification (LOQs) of the method, varied between 1 ng L-1 for 2-isobutyl-3-methoxypyrazine (IBMP) and 2.5 ng L-1 for 2-ethyl-3-methoxypyazine (EMP). The optimized method was applied to commercial wines from different countries, where IBMP was quantified at concentrations ranging from 2.2 to 9.9 ng L-1.