Development of a new stir bar sorptive extraction method for the determination of medium‐level volatile thiols in wine

• Published in: Journal of separation science Vol. 37; no. 14; pp. 1867 - 1872
• Main Authors: Elpa, Decibel, Durán‐Guerrero, Enrique, Castro, Remedios, Natera, Ramón, Barroso, Carmelo G
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley-VCH 01.07.2014; Blackwell Publishing Ltd; Wiley; Wiley Subscription Services, Inc
• Subjects: Acetates; Adsorption; Bars; Biological and medical sciences; Coating; desorption; detection limit; EG-Silicone Twister; ethylene glycol; Extraction; Extraction processes; Factorial design; Fermented food industries; Food industries; Fundamental and applied biological sciences. Psychology; gas chromatography; Gas Chromatography-Mass Spectrometry; Linearity; mass spectrometry; mixing; odors; Optimization; silicone; sodium chloride; Solid Phase Extraction - instrumentation; Solid Phase Extraction - methods; Sorption; Stir bar sorptive extraction; Sulfhydryl Compounds - chemistry; Sulfhydryl Compounds - isolation & purification; Thiols; Vitaceae; Volatile thiols; Volatilization; Wine; Wine - analysis; Wines; Wines and vinegars; Trace analysis; Wine; Ethylene glycol; Thiol; Chemical analysis; Coating material; Coupled method; Thermodesorption; Volatile organic compound; Optimization; Chemical enrichment; Gas chromatography; Sample preparation; Experimental design; EG-Silicone Twister; Volatile thiols; Aroma; Stir bar sorptive extraction; Factorial design; Siloxane polymer; Mass spectrometry; Chemometrics; Glycol; Quantitative analysis
• ISSN: 1615-9306; 1615-9314
• DOI: 10.1002/jssc.201400308

A fast, simple, and reliable analytical method for the determination of medium‐level volatile thiols in wines is presented. Stir bar sorptive extraction using ethylene glycol‐silicone coated stir bars has been used in combination with thermal desorption gas chromatography with mass spectrometry for the analysis of 4‐mercapto‐4‐methylpentan‐2‐one, 2‐furanmethanethiol, 3‐mercaptohexyl acetate, and 3‐mercaptohexanol in wine. Optimization of the extraction technique was performed using a two‐level fractional factorial design. For the extraction step, the optimum conditions were: Ethylene glycol and silicone coated stir bars, pH at 3.5, sample volume of 25 mL, extraction time of 90 min, NaCl content 4.0 g, and stirring speed at 500 rpm. The optimized method achieved good linearity for all studied compounds (r² > 0.995) and it provided detection limits of 21.52, 0.36, 0.73, and 2.55 μg/L for 4‐mercapto‐4‐methylpentan‐2‐one, 2‐furanmethanethiol, 3‐mercaptohexyl acetate, and 3‐mercaptohexanol, respectively. It was repeatable, with precisions lower than 18% relative standard deviation for both intraday and interday repeatability. The developed procedure is suitable for the determination of these kinds of compounds when they are present at medium concentration levels. It was finally applied to real wine samples with negative aroma derived from the high concentration levels of these compounds.