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Gradient and isocratic HPLC separated as many as 38 carotenoid components in extracts from fruit juices. Several oxygenated carotenoids (xanthophylls), hydrocarbon carotenoids, and carotenol mono- and bis-fatty acid esters were identified. Structural elucidation was based on UV/vis spectroscopy, matrix-assisted laser desorption ionization (MALDI) post-source-decay (PSD) mass spectrometry, and comparison with synthetic reference compounds. Straight-chain fatty acid esters (caprate, laurate, myristate, palmitoleate, palmitate, oleate) of β-cryptoxanthin were identified as major carotenoid constituents in tangerine juice concentrate. Fatty acid components were identified by MALDI PSD fragment ion analysis. The xanthophylls violaxanthin, luteoxanthin, neoxanthin, taraxanthin, antheraxanthin, mutatoxanthin, β-cryptoxanthin-5,6:5‘,6‘-diepoxide, lutein, zeaxanthin, α-cryptoxanthin, and β-cryptoxanthin were present in the extracts of saponified tangerine concentrate. The chromatographic profiles of orange juice concentrate showed marked differences from those of tangerine concentrate. In the saponified extract, the oxygenated carotenoid zeaxanthin predominated over β-cryptoxanthin. Keywords: Carotenoids; carotenol esters; carotenoid analysis; mass spectrometry; matrix-assisted laser desorption ionization

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Laser desorption/ionization mass spectrometry (LDI-MS) at 337 nm laser wavelength was used to analyze retinol and several long-chain fatty acid esters of retinol. Employing this ionization technique helped to overcome the inherent problems resulting from thermal instability of retinyl esters which render this group of compounds rather difficult for standard ionization techniques. Mass spectra were recorded with a linear time-of-flight instrument in positive ion mode. Under these conditions, retinyl esters formed radical molecular ions (M.+) and in addition fragmented by elimination of the fatty acyl chain to uniformly form a peak at m/z = 269 u. The elimination of carbon dioxide was also observed in the spectra. The method is suitable to identify specific retinyl esters in complex mixtures of these compounds. A gradient reversed-phase high-performance liquid chromatography (HPLC) is described for the separation of retinol and 15 related fatty acid esters within 28 min. HPLC was applied to separate retinyl esters from rat liver extracts. The LDI mass spectrum of the collected HPLC fraction of rat liver extract showed the molecular parent ions of retinyl myristate, pentadecanoate, palmitoleate, palmitate, heptadecanoate, linoleate, oleate, stearate, and 3,4-didehydroretinyl palmitate. LDI-MS was found to be more appropriate than matrix-assisted laser desorption/ionization for the described analytical task.