Journal of Chromatography A 2007-04-06

Quantitative determination of wine polyfunctional mercaptans at nanogram per liter level by gas chromatography-negative ion mass spectrometric analysis of their pentafluorobenzyl derivatives.

Laura Mateo-Vivaracho, Juan Cacho, Vicente Ferreira

Index: J. Chromatogr. A. 1146(2) , 242-50, (2007)

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Abstract

A fast method for the determination of aroma-powerful polyfunctional thiols at nanogram per liter level has been developed and applied to wine. A small volume of wine (6 mL) was extracted with 1.5 mL of benzene containing four internal standards. Pentafluorobenzyl derivatives of mercaptans were formed in the extract by adding small amounts (100 mg L(-1)) of pentafluorobenzyl bromide and a strong alkali: 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). After washing with a water:methanol (5:1) solution 0.5M in HCl, 20 microL of the extract was directly injected into a gas chromatograph. Derivatives were detected by negative ion mass spectrometry. The method makes it possible to simultaneously determine 2-furfurylthiol (2-furanmethanethiol) (FFT), 4-mercapto-4-methyl-2-pentanone (MP), 3-mercaptohexylacetate (MHA) and 3-mercaptohexanol (MH). Inconsistent results were obtained for 2-methyl-3-furanthiol (MF). Detection limits were 0.5 ng L(-1) (FFT), 0.1 ng L(-1) (MP), 0.6 ng L(-1) (MHA) and 7 ng L(-1) (MH), well below the corresponding odor detection thresholds. Method repeatability (10%