Stable isotope analysis of grape juices and fermented products involving 2H-NMR spectroscopy and isotope ratio mass spectroscopy was carried out in combination with elemental determinations performed by atomic absorption spectroscopy using flame and thermal ionisation. One hundred and sixty five grape samples were carefully collected in well-defined vineyards of France situated in Alsace, Burgundy, Beaujolais and the Loire Valley. Moreover, the samples from Burgundy were picked from four typical Appellations (CBtes de Nuits, CBtes de Beaune, CBtes Chalonnaises and Mficonnais) in order to 'zoom' the approach to smaller production areas. An exhaustive statistical evaluation of the 165 x 16 data set was carried out by analysis of variance and principal component analysis. To conclude this study, the classification of the samples in typical Appellations was carried out by discriminant analysis with a nearly 100% degree of achievement.

A great variety of techniques has been used to study deuterium-protium partitioning in exchanging systems at equilibrium. In this context it is shown that the determination of site-specific isotope contents by ZH-NMR at natural abundance provides simple and direct access to thermodynamic isotope fractionation factors. This method avoids the recourse to deuterated species and therefore the approximations inherent in the analysis of complex isotopomeric mixtures. A number of slowly exchanging systems involving OH, NH, or SH groups and water offer suitable conditions (large chemical shift differences, moderate line widths, ...) for the relatively accurate determination of thermodynamic fractionation factors. Moreover multiple fractionations can be observed and compared in ternary mixtures.Knowledge of the thermodynanic fractionation factors in exchanging systems at equilibrium is of considerable interest for interpreting chemical or biochemical mechanisms. In this respect, hydrogen isotope exchange processes between water and exchangeable groups (OH, N H , SH, ...) occur frequently in biological media. A great aeal of effort has been devoted to the determination of the equilibrium partitioning of deuterium and 0002-7863/92/1514-7089$03.00/0 protium using a wide variety of e~perimenta1I-l~ and theoretical14 methods. The experimental determinations require the use of (1) (a) Rolston, J. H.; den Hartog, J.; Butler, J. P.

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Isotopic ratios 'H NMR

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