title: An improved method for the analysis of 2-aminoacetophenone in wine based on headspace solid-phase microextraction and heart-cut multidimensional gas chromatography with selective detection by tandem mass spectrometry.
abstract: Heart-cut multidimensional gas chromatography coupled to selective mass spectrometric detection (H/C MDGC-MS-MS) was shown to be a suitable combination for analysis of the key component for the wine off-flavor named "atypical aging off-flavor" (german: "Untypische Alterungsnote", UTA), 2-aminoacetophenone (2-AAP). Headspace solid phase microextraction (HS-SPME) was applied as an easy to automate sample preparation step suiting routine control situations. During method development two critical aspects were found, of which one is the chemical degradation of the neat substance, leading to signal reduction and a false response behavior. A second aspect is the pH stability of the deuterated isotopologue 1-(2-aminophenyl)-2,2,2-trideuterio-ethanone (2-AAP-d3) used for quantification via a stable isotope dilution assay. Despite an earlier suggestion to increase the extractable amount of 2-AAP and its isotopic standard in the headspace, alkalization of 2-AAP-d3 containing aqueous samples were found to be critical. In such a milieu a deuterium exchange can then cause erroneous quantitative results. The method proposed in our study thus uses native wine pH conditions and proved to be suitable for routine control with respect to the detection of the "atypical aging off-flavor" in wine at concentration levels below its sensory threshold of about 1μgL-1. Good linearity was obtained in the calibrated range from 0.1-8μgL-1(y=1,2338x+0,1029, R=0,9985) with limits of detection or quantification being 0.01 and 0.14μg/L, respectively.
authors.affiliation: Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Institute for Viticulture and Oenology, Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany; University Duisburg-Essen, Faculty for Chemistry, Instrumental Analytical Chemistry, Universitätsstraße 5, 45141 Essen, Germany. Electronic address: hans-georg.schmarr@dlr.rlp.de.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Schmarr
authors.affiliation: Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Institute for Viticulture and Oenology, Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Keiser
authors.affiliation: Dienstleistungszentrum Ländlicher Raum (DLR) Rheinpfalz, Institute for Viticulture and Oenology, Breitenweg 71, 67435 Neustadt an der Weinstraße, Germany.
authors.forename: Susann
authors.initials: S
authors.lastname: Krautwald
mesh_terms: D000098:Acetophenones / Q000032:analysis* / Q000737:chemistry; D000468:Alkalies / Q000737:chemistry; D002138:Calibration; D003903:Deuterium / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007201:Indicator Dilution Techniques; D012015:Reference Standards; D015203:Reproducibility of Results; D052617:Solid Phase Microextraction / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013997:Time Factors; D014920:Wine / Q000032:analysis*
chemical_list: D000098:Acetophenones; D000468:Alkalies; C055495:2-aminoacetophenone; D003903:Deuterium
keywords: 2-Aminoacetophenone; Atypical aging off-flavor of wine; Heart-cut multidimensional gas chromatography; Mass spectrometric detection; Proton exchange in alkaline pH; Stable isotope dilution assay