QuEChERS Method for the Determination of 3‑Alkyl‑2‑Methoxypyrazines in Wines by Gas Chromatography-Mass Spectrometry

Abstract

A new method for determining 3-isopropyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine, and 3-isobutyl-2-methoxypyrazine in wines is presented. A modified quick, easy, cheap, effective, rugged, and safe method and gas chromatography-mass spectrometry (GC-MS) were used for sample preparation and compound determination, respectively. The analytes were extracted from wine (30 mL) with 1 mL toluene, in the presence of 12 g anhydrous MgSO4 and 3 g NaCl. Cleanup of the toluene phase was performed by a miniaturized dispersive solid-phase extraction with a combination of anhydrous CaCl2 (25 mg), anhydrous MgSO4 (25 mg), and primary-secondary amine (10 mg), which was effective for minimizing co-extractives and matrix effects. GC-MS parameters were also tuned up to optimize limits of detection between 4.2 and 7.1 ng L−1. The overall recoveries (trueness) of the method ranged between 71 and 87 % for the white and red wine samples, respectively, spiked at 40 and 100 ng L−1, with relative standard deviations below 21 %. The method was applied for the determination of target methoxypyrazines in the samples of commercial wines from Argentina.