As a result of the atmospheric atomic experiments carried out in the 1960s a method for short-term dating of wines and spirits could be based on the determination of the 14C radioactivity of ethanol. However, due to the turnover of atmospheric this method is no longer applicable to the most recent 14CO 2 samples. The aptitude of stable isotopes of carbon and hydrogen to provide new probes for dating brandies such as cognacs and armagnacs is evaluated. The overall carbon isotope ratio of ethanol is measured by isotope ratio mass spectrometry and the site-speciÐc hydrogen parameters of the methyl, and (D/H) I , methylene, sites are determined by the SNIF-NMR method. The iso-(D/H) II , topic results can be interpreted in terms of fractionation phenomena associated with thermo-kinetic evaporation undergone in the casks during the ageing period. A theoretical estimation of the vintage founded on this isotopic evolution requires the knowledge of the isotope ratios of the starting product. In principle, these values can be estimated on the basis of the meteorological parameters associated with the growing period of the corresponding vine. However, although the combined contributions of climatic e †ects and of evaporation phenomena conveniently explain the general isotopic behaviour, the inÑuence of oenological practices such as ullage (replacement of the amount of a liquid lost in a cask by evaporation) must also be considered. Further progress towards an unequivocal dating procedure using stable isotope ratios is expected from the access to isotope databanks of the wine precursors.
1998 SCI.