Electrospray tandem mass spectrometric analysis of zeaxanthin and its oxidation products

Jeevan Kumar Prasain, Ray Moore, John S. Hurst, Stephen Barnes, Frederik J.G.M. Van Kuijk

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Carotenoids have been implicated in protection of the eye from light-mediated photo-toxicity caused by free radicals. Under conditions of normal oxidative stress the carotenoids serve as protective antioxidants; however, when the oxidative stress exceeds the antioxidant capacity, carotenoids can be oxidized into numerous cleavage products. The determination and identification of oxidized carotenoids in biological samples remains a major challenge due to the small sample size and low stability of these compounds. We investigated the reaction of various zeaxanthin cleavage products with O-ethyl hydroxylamine to evaluate their levels in a biological sample. For this, a sensitive and specific electrospray tandem mass spectrometry (ESI-MS/MS) was developed, avoiding the classical lower sensitive and specific HPLC-UV and fluorescence absorption methods. Protonated molecules [M + H]+ of carotenoids upon collision-induced dissociation produced a number of structurally characteristic product ions. A series of complicated clusters of product ions differing in 14 (CH2)and 26 (C2H 2)Da was characteristic of the polyene chain of intact carotenoids. All carotenoid ethyl oximes of zeaxanthin cleavage products were characterized by the losses of 60 and 61 Da in their MS/MS spectra. Through the application of the LC/MS/MS method, we identified two oxime derivatives of 3-hydroxy-β-ionone and 3-hydroxy-14′-apocarotenal with protonated molecules at ra/z 252 and mlz 370 respectively, in a human eye sample.

Original languageEnglish (US)
Pages (from-to)916-923
Number of pages8
JournalJournal of Mass Spectrometry
Issue number7
StatePublished - Jul 2005


  • Analysis
  • Electrospray ionization
  • Oxidized carotenoids
  • Oxime
  • Tandem mass spectrometry


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