Quantitative determination of α-ionone, β-ionone, and β-damascenone and enantiodifferentiation of α-ionone in wine for authenticity control using multidimensional gas chromatography with tandem mass spectrometric detection

Native concentrations of alpha-ionone, beta-ionone, and beta-damascenone were studied in various authentic and commercial wines. In addition, the enantiomeric distribution of alpha-ionone was determined and its merits as a potential marker for aroma adulteration in wine were discussed. For extraction of volatiles, headspace solid-phase microextraction (HS-SPME) was applied, followed by heart-cut multidimensional gas chromatography coupled to tandem mass spectrometric detection for trace-level analysis. The enantioselective analysis of alpha-ionone was achieved with octakis(2,3-di-O-pentyl-6-O-methyl)-gamma-cyclodextrin as the chiral selector in the separation column for gas chromatography (GC). In all the authentic wines studied, alpha-ionone showed a high enantiomeric ratio in favor of the (R)-enantiomer. Since an illegal addition of alpha-ionone in a racemic form changes the enantiomeric ratio, this ratio may serve as an adulteration marker. Concentrations varied between < LOD to 0.081 mu g/L for alpha-ionone, < LOD to 1.0 mu g/L for beta-ionone, and 0.03-10.3 mu g/L for beta-damascenone. Commercial wines of suspiciously strong flavor yielded concentrations up to 4.6 mu g/L for alpha-ionone, 3.6 mu g/L for beta-ionone, and 4.3 mu g/L for beta-damascenone. Elevated alpha- and beta-ionone concentrations serve as additional indicators for a potential adulteration. In order to classify the concentrations of the analytes in the context of their odor activity in wine, odor thresholds were determined.