Authentication of Bitter Almond Oil and Cinnamon Oil: Application of the SNIF-NMR Method to Benzaldehyde

The detection of adulterated bitter almond and cinnamon oils can be achieved by means of the SNIF-NMR method using benzaldehyde as a molecular probe. It is demonstrated that the site specific deuterium contents of benzaldehyde allow the determination of the origin of the molecule:  synthetic (ex-toluene and ex-benzal chloride), natural (ex-kernels from apricots, peaches, and cherries and ex-bitter almond) and semisynthetic (ex-cinnamaldehyde extracted from cinnamon). A strategy resorting to the transformation of cinnamaldehyde into benzaldehyde has been exploited to study the origin of cinnamaldehyde. An analytical method for routine characterization of the genuineness of bitter almond and cinnamon oils is proposed. The repeatability of the 2H-NMR measurements on benzaldehyde and the capability for both proving and quantifying adulterations are estimated. Keywords: Benzaldehyde; cinnamaldehyde; bitter almond oil; cinnamon oil; SNIF-NMR; authentication; adulteration; retroaldolization