Determination of carotenoids and their esters in fruits of Lycium barbarum Linnaeus by HPLC–DAD–APCI–MS

The fruit of Lycium barbarum Linnaeus, a traditional Chinese herb containing functional components such as carotenoids, flavonoids and polysaccharides, has been widely used in the health food industry because of its possible role in the prevention of chronic disease like age-related macular degeneration. The objectives of this study were to develop a high performance liquid chromatography–photo diode array detection–mass spectrometry (HPLC–DAD–MS) method with atmospheric pressure chemical ionization (APCI) mode for qualitative and quantitative analyses of carotenoids in fruits of L. barbarum. Dried samples of L. barbarum were subjected to extraction without saponification or extraction followed by saponification. A C30 column with a gradient mobile phase of methylene chloride (100%) and methanol–acetonitrile–water (81:14:5, v/v/v) was used to separate carotenoids, with a total of 11 free carotenoids and 7 carotenoid esters being resolved from unsaponified and saponified L. barbarum extracts within 51 and 41 min, respectively. The fatty acid composition of carotenoid esters was confirmed by gas chromatography. Zeaxanthin dipalmitate (1143.7 μg/g) was present in the largest amount, followed by β-cryptoxanthin monopalmitate and its two isomers (32.9–68.5 μg/g), zeaxanthin monopalmitate and its two isomers (11.3–62.8 μg/g), all-trans-β-carotene (23.7 μg/g) and all-trans-zeaxanthin (1.4 μg/g).