Vanillin isotopic analysis

The price of synthetic vanillin has dropped to about 10 kg-1 due to increased production in China, which is now the number one supplier. In view of the very large price difference, analytical methods (isotope analysis) have been developed to distinguish between natural and synthetic vanillin. 

As vanilla, as a result of its high price, is often adulterated or diluted, a number of publications deal with the detection of piperonal, coumarin, ethyl vanillin, vanitrop and others. Whereas these adulterations can be detected rather easily, the addition of synthetic vanillin, as long as it remains within certain proportions, can only be certified by the expensive isotope analysis (deuterium, C content) [296, 297, 298, 299[. 

J. Bricout, J.Ch. Fontes, L. Merlivat (1974) Detection of synthetic vanillin in vanilla extracts by isotopic analysis. J. Assoc. Off. Anal. Chem. 57, 713-715... 

The following points will be presented successively to illustrate the ability of isotopic analysis to trace back the origin of vanillin ... 

The biosynthetic origins of vanillin can be determined by the analysis of naturally occurring isotope ratios (in practice, chiefly 2H/1H and 13C/12C), using isotope ratio-mass spectrometry (IR-MS) and nuclear magnetic resonance (site-specific natural isotope fractionation SNIF-NMR ). Isotopic ratio... 

The coupling of SNIF-NMR with stable isotope ratio analysis/mass spectrometry has been the basis of a method for detection of adulteration of maple syrup with beet, cane, or com sugar.192 Adulteration of mustard oil by the addition of synthetic allyl isothiocyanate, its major component, is of economic interest, and therefore a combined NMR and mass spectrometry method was developed, enabling the distinction between the natural and the synthetic compound, as well as the determination of the geographical origin of natural mustard oils.193 Similar methods have been used for the analysis of flavourings such as vanilla flavour (vanillin and p-hydroxybenzaldehyde),194195 benzaldehyde,196 and others.197... 

Hoffman, P. Salb, M. Isolation and stable isotope ratio analysis of vanillin. J. Agric. Food Ghent. 1979, 27, 352- 355. 

The determination of the isotopic composition of the carbon in organic compounds has become a useful tool in differentiating between natural and synthetic products. Both the determination of the stable isotopic ratio of and and the determination of the 0 have been sucessfully applied to a variety of products to determine sophistication (10, 11). Since the application of GC isolation and stable isotope ratio analysis was successful in the detection of vanilla/vanillin sophistication (4), it was decided to apply the same methodology to cinnamon/cinnamic aldehyde. As can be seen from Table 1, this procedure could not differentiate between natural and synthetic cinnamic aldehyde the natural compound apparently is biosynthesized via the Calvin cycle, and synthetic... 

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