Spatial and temporal dependence of the C-13 and C-14 isotopes of wine ethanols

More than 1000 authentic samples of ethanols were extracted by quantitative distillation from vintage wines and brandies prepared from grapes harvested in well-defined regions and years. The C-13 contents of these ethanols were determined by isotope ratio mass spectrometry (IRMS) and the C-14 activity of most of these samples was determined by liquid scintillation counting (LSC). We show that the C-13 content of a C-3 plant such as grape vine, which strongly depends on water availability, spans nearly a 10 parts per thousand range worldwide. The efficiency of the C-14 content of grape ethanols as a tracer of the CO2 turnover after the peak of the nuclear test in the 1960s is also discussed in terms of geographical effects. Finally, the necessity of a multi-isotopic approach, including C-13 and C-14 isotopes, for detecting sophisticated adulterations is illustrated in the case of wines and brandies.