Carotenoids mass separation

This chapter focuses on the extraction and handling of retinoids and carotenoids, their separation by various chromatographic techniques, and their detection and quantitation, primarily by absorption spectrophotometry, fluorescence, and mass spectrometry. A variety of other methods exist for their identification and characterization, including circular dichroism (333), infrared spectroscopy (334), resonance Raman spectroscopy (335), NMR spectroscopy (336), and x-ray crystallography (337). Although some of these procedures require substantial amounts of a retinoid or a carotenoid in an essentially pure form for study, others, such as resonance Raman spectroscopy, are extremely sensitive and can be used to detect the localization of carotenoids in single cells (338,339). 

Because of their considerable role in human wellfare, carotenoids have been measured not only in plants as primary sources and in human and animal tissues but also in a wide variety of other matrices to find new and economical sources for carotenoids. Thus, the carotenoid accumulation capacity of algae and microalgae have been vigorously investigated. A validated liquid chromatography-electrospray mass spectrometry method have been developed and employed for the separation and quantitative determination of... 

The original reference for LC-APCI-MS of carotenoids, containing essential information for carrying out C30 HPLC separations with on-line APCI mass spectrometric detection. 

Lacker T, Strohschein S and Albert K, Separation and identification of various carotenoids by C30 reversed-phase high-performance liquid chromatography coupled to UV and atmospheric pressure chemical ionization mass spectrometric detection. J Chromatogr A 854 37 14 (1999). 

Often a mass spectrometer is interfaced with an HPLC-PDA system. This technique is especially useful because isobaric species can be chromatographically separated before entering the MS. Interestingly, there are a large number of isobaric species in the field of carotenoids, such as lycopene, [3-carotene, oc-carotene, and y-carotene which all have a parent mass of 536 mu, or (3-cryptoxanthin, oc-cryptoxanthin, zeinox-anthin, and rubixanthin which all have a parent mass of 552 mu. 

In addition, the development of even softer (i.e. gentler) ionization techniques (beyond those already discussed) will improve the sensitivity of mass spectrometry as a tool for carotenoid identification and quantitation. Interfacing future ionization techniques with other MS tools may further expand opportunities. For example, a softer ionization technique that preserves carotenoid geometrical isomers in-source might allow isomers to be successfully separated via IMS and eliminate the need for prior separation by HPLC. 

Physical Methods.—Electronic absorption, mass, n.m.r., and increasingly c.d. spectra are used routinely in the elucidation of new carotenoid structures and the characterization of synthetic products. Spectroscopic data for individual carotenoids may be found in many of the papers already cited. The papers quoted in this section are those which are concerned largely or entirely with one or more of the physical methods used for the separation, assay, and spectroscopic analysis of carotenoids and related compounds. 

Degraded Carotenoids Physical Methods Separation and Assay N.M.R. Spectroscopy Mass Spectrometry Chiroptical Methods Electronic Absorption Spectroscopy Infrared and Resonance Raman Spectroscopy Other Spectroscopic Techniques Miscellaneous Physical Chemistry Photoreceptor Pigments Biosynthesis and Metabolism Stereochemistry Enzyme Systems Inhibition and Regulation... 

Essays in the older hterature (42, 43) deahng with the purification and characterisation of carotenoids have been superseded by recent accounts of the application of HPLC to carotenoid analysis and separation (551) and of modern techniques of high field n.m.r. spectroscopy to elucidation of their structures (216). The mass spectra of several of the fungal carotenoids discussed above have been studied in detail by Liaaen-Jensen (217). 

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