title: Ethyl propiolate derivatisation for the analysis of varietal thiols in wine.
abstract: Varietal thiols [3-mercaptohexan-1-ol (3MH), 3-mercaptohexyl acetate (3MHA) and 4-mercapto-4-methylpentan-2-one (4MMP)] have been extensively studied in the recent literature. Nonetheless the hardest obstacle for research focussing on this class of compounds is the lack of quick, user-friendly and sensitive analytical methods. The current paper presents the use of ethyl propriolate (ETP) as a novel derivatising agent to quantify varietal thiols and the first time quantification of the thiol-ETP adducts via gas chromatography-mass spectrometry. Method optimisation including choice of the best SPE cartridge, derivatisation pH and adducts stability is presented. Validation of the method via stable isotope dilution was carried out. Detection limits in both model wine (4MMP 7.2ng/L, 3MHA 40.0ng/L and 3MH 91.2ng/L) and white wine (4MMP 24.5ng/L, 3MHA 120.9ng/L and 3MH 194.6ng/L) for the novel ETP-based method were lower than those obtained with the p-HMB method. Finally, 14 New Zealand Sauvignon blanc were analysed with both the new method and the organo-mercury based procure: good correlations were obtained for 3MH and 3MHA. Detection limits obtained with the new methods, its rapidity and reproducibility make this protocol perfectly suitable for oenological purposes.
authors.affiliation: School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: Mandy
authors.initials: M
authors.lastname: Herbst-Johnstone
authors.forename: Federico
authors.initials: F
authors.lastname: Piano
authors.forename: Nina
authors.initials: N
authors.lastname: Duhamel
authors.forename: David
authors.initials: D
authors.lastname: Barker
authors.forename: Bruno
authors.initials: B
authors.lastname: Fedrizzi
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D016014:Linear Models; D009812:Odorants / Q000032:analysis; D011422:Propionates / Q000737:chemistry*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D013438:Sulfhydryl Compounds / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D014920:Wine / Q000032:analysis*
chemical_list: D000480:Alkynes; D011422:Propionates; D013438:Sulfhydryl Compounds; C544697:ethyl propiolate
keywords: Aroma; Ethyl propiolate; SPE-GC–MS; Varietal thiols; Wine