| Abstract
| - Considering the increasing nutritional and commercial importance of carotenoids, there is an interest in developing a reliable method for authenticity assessment of these compounds. Applying isotope ratio mass spectrometry using elemental analysis in the “combustion” (C) and “pyrolysis” (P) modes (EA−C/P−IRMS), the δ13CV-PDB and δ2HV-SMOW values of selected carotenoids and α/β-carotene-based commercial dietary supplements were determined in comparison to those of synthetic and “natural” references. The δ13CV-PDB and δ2HV-SMOW values of synthetic β-carotene samples (n = 4), ranging from −25.3‰ to −26.4‰ and from −144‰ to −155‰, respectively, differed clearly from the data determined for carotenoids from various natural sources, including C3 plant material (n = 9; δ13CV-PDB ranging from −28.5‰ to −32.8‰ and δ2HV-SMOW from −180‰ to −275‰) and microalgae Dunaliella salina (n = 1; δ13CV-PDB value of −15.6‰ and δ2HV-SMOW value of −191‰). From five commercial dietary supplements under study, two revealed δ13CV-PDB and δ2HV-SMOW values in areas as found for synthetic references, and the other three had values near those of biotechnological β-carotene produced by D. salina. The δ13CV-PDB and δ2HV-SMOW values recorded for natural lycopene (n = 4) and lutein (n = 5) ranged from −31.1‰ to −31.8‰ and from −180 to −201‰, as well as from −28.8‰ to −32.2‰ and from −186‰ to −245‰, respectively. Synthetic canthaxanthin (n = 3) exhibited δ13CV-PDB and δ2HV-SMOW values ranging from −25.0‰ to −28.6‰ and from −133‰ to −153‰, respectively. The EA−C/P−IRMS application of this study showed that the natural stable isotopic composition of carotenoids is a powerful tool for determining their origin.
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