Cholesterol, a powerful C isotopic biomarker.

Cholesterol is related to many health diseases and is considered as a metabolic disorder biomarker. This compound, present in all food products of animal origin, can also be used as food authentication biomarker. In this work and for the first time, positional C isotope contents were determined for such a high molecular weight compound. This was possible by means of NMR using adiabatic refocused INEPT. In order to test the potential of this approach for discrimination, hen eggs from different origins were collected. Quantitative extraction of egg yolk cholesterol was optimized, and partial reduced molar fractions of its different C isotopomers were used as predictors in discriminant analysis. Compared with the global C isotopic composition determined using isotope ratio monitoring by Mass Spectrometry, the relative content of cholesterol C isotopomers added valuable power to sample classifications according to their origins. This study paves the way to isotopomics of other steroids and similar molecular weight compounds.