Confirmation of the identity of the carotenoids of tropical fruits by HPLC-DAD and HPLC-MS

The color and the biological activities of carotenoids are intimately related to their structures. Thus, conclusive identification is an important part of carotenoid analysis. Brazil has a wide variety of carotenoid-rich fruits with markedly varied carotenoid composition, qualitatively and quantitatively. Identification of the carotenoids can therefore be a delicate task. The present work had the objective of confirming the identity of carotenoids in acerola (Malpighia glabra L.), camu-camu (Myrciaria dubia), pequi (Caryocar brasiliense Camb.) and pitanga (Eugenia uniflora L.). The following identifying parameters were employed: chromatographic behavior in HPLC and TLC, UV–visible absorption spectra, chemical reactions and mass spectra. The HPLC analyses were carried out with a liquid chromatograph equipped with photodiode array and mass detectors and a monomeric C18 column ODS2, 3 μm, 4.6 i.d×150 mm. With carotenoids of known structures, conclusive identification in HPLC can be achieved by the combined use of the retention times and co-chromatography with authentic carotenoid standards, the UV–visible absorption spectra and the mass spectra. In the absence of a mass detector, the identification is conclusive if chemical tests, particularly with the xanthophylls, are done, along with the chromatographic data and UV–visible absorption spectra.