Flavor authenticity studies by 2H/1H ratio determination using on-line gas chromatography pyrolysis isotope ratio mass spectrometry

Based on H-2/H-1 ratio measurements of commercial synthetic and "natural" references, the recently developed on-line gas chromatography pyrolysis isotope ratio mass spectrometry (HRGC-P-IRMS) technique was used to determine the delta H-2(SMOW) values of the flavor compounds decanal, linalool, and linalyl acetate, as well as those of E-2-hexenal and E-2-hexenol in foods and essential oils. In preceding model studies, the influence of sample preparation steps (simultaneous distillation extraction, SDE; solvent extraction, SE; liquid liquid extraction, LLE) on the delta H-2 values was found to be negligible. For decanal, the typical H-2 abundance, with higher content of 2H for synthetic material (delta H-2(SMOW) from -90 to -156 parts per thousand) and lower H-2 content for natural references (delta H-2(SMOW) from -138 to -262 parts per thousand) was observed. Although the delta H-2 data recorded for linalool did not allow one to distinguish between synthetic (delta H-2(SMOW) from -207 to -301 parts per thousand) and natural (delta H-2(SMOW) from -234 to -333 parts per thousand) materials, the situation was somewhat more encouraging for linalyl acetate; delta H-2(SMOW) values from -199 to -239 parts per thousand and from -213 to -333 parts per thousand were found for synthetic and natural samples, respectively. E-2-Hexenal and E-2-hexenol showed clear-cut origin-dependent differences in their H-2/H-1 ratios; that is, delta H-2(SMOW) values from -14 to -109 parts per thousand and from -263 to -415 parts per thousand as well as from -41 to -131 parts per thousand and from -238 to -348 parts per thousand were recorded for products from synthetic and natural origins, respectively.