Selective preconcentration of volatile mercaptans in small SPE cartridges: Quantitative determination of trace odor‐active polyfunctional mercaptans in wine

Abstract

A general procedure for the selective preconcentration and purification of mercaptans has been developed. Mercaptans are strongly retained in a small (20 mg) SPE cartridge containing p-hydroxymercurybenzoate. The cartridge can then be rinsed with relatively high volumes of polar (water/methanol mixtures) and non-polar (pentane or pentane/ ether mixtures) rinsing solutions to remove nearly all volatile compounds lacking a thiol functionality. Retained analytes are further eluted with a small volume of an organic solvent containing 1,4-dithioerythritol. Some basic aspects of the strategy, such as the retention of p-hydroxymercurybenzoate in the sorbent and its stability versus different rinsing and eluting systems, have been studied in depth. Light sulfur compounds contained in water or wine, including mercaptans such as methanethiol or thioethers, such as diethyl sulfide, can be quantitatively extracted, although only mercaptans can be quantitatively recovered if a polar rinsing is applied. The strategy has been applied to the GC-MS quantitative determination of some trace polyfunctional mercaptans that are key aromas in wine, such as 2-methyl-3-furanthiol, 2-furfurylthiol, 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexyl acetate or 3-mercaptohexanol. The developed method reaches detection limits in the ng/L range and has a satisfactory analytical behavior, being quite simple and fast.

Application of Gas Chromatography on the Evaluation of Grape and Wine Aroma in Atlantic Viticulture (NW Iberian Peninsula)

“…polyfunctional mercaptans, methoxypyrazines and terpenoids (Culleré et al, 2003;López et al, 2002López et al, , 2011Mateo-Vivaracho et al, 2009;Weldegergis et al, 2011). However, its major advantage is the application to determine the nature and concentration of free and glycosidically bound volatile compounds in grape juices and wines.…”

Review of the role and methodology of high resolution approaches in aroma analysis

“…To-date such compounds are separated and purified on the basis of p-hydroxymercuribenzoate (pHMB)-volatile thiol conjugate formation on a Dowex resin, which dissociated in cysteamine solution, and may then be extracted by organic solvent for GC-O analysis [41,43,45]. Mateo-Vivaracho et al [40] proposed a micro-size SPE separation approach consisting of PS-DVB conjugated with pHMB for selective preconcentration and purification of mercaptans in wine aroma extract. The method was claimed to be simple and fast, and successfully recovered trace polyfunctional mercaptans that are key aromas in wine, such as 2-methyl-3-furanthiol, 2-furfurylthiol, 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexyl acetate or 3-mercaptohexanol, down to ng L À1 range.…”

“…Ion-exchange chromatography, based on electrostatic interactions, allows specific analytes or groups such as acids and thiols to be targeted for separation in the aroma extract [24,[40][41][42][43][44][45]]. An amino ion-exchange column was used to fractionate the long chain acid target from an extract of wine and cheese, when classic acid/ base separation failed to do so [24].…”

Micro versus macro solid phase extraction for monitoring water contaminants: A preliminary study using trihalomethanes

“…Most of the studies that have been published relate to extracting compounds such as proteins (Tong et al, 1999), cannabinoids (Montesano et al, 2014) or pharmaceuticals (Shen et al, 2006) from biological matrices such as blood or urine. There have also been a few studies looking at contaminants in food (Huang et al, 2012) and wine (Mateo-Vivaracho et al, 2009) but the use of micro SPE in environmental assessment appears to be limited to a paper on assessing the use of one form of the technology for trace cadmium and lead determination, and this required the use of a special PVC adapter rather than a commercial system as used in this research (Anthemidis et al, 2011).…”