Sodiation as a tool for enhancing the diagnostic value of MALDI-TOF/TOF-MS spectra of complex astaxanthin ester mixtures from Haematococcus pluvialis

Y.J.A. Weesepoel, J.P. Vincken, R.M. Pop, K. Liu, H. Gruppen

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

The microalga Haematococcus pluvialis produces the pigment astaxanthin mainly in esterified form with a multitude of fatty acids, which results in a complex mixture of carotenol mono- and diesters. For rapid fingerprinting of these esters, matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF/TOF-MS) might be an alternative to traditional chromatographic separation combined with MS. Investigation of ionization and fragmentation of astaxanthin mono- and diester palmitate standards in MALDI-TOF/TOF-MS showed that sodium adduct parent masses [M + Na]+ gave much simpler MS2 spectra than radical / protonated [M]+¿ / [M+H]+ parents. [M + Na]+ fragments yielded diagnostic polyene-specific eliminations and fatty acid neutral losses, whereas [M]+¿ / [M+H]+ fragmentation resulted in a multitude of non-diagnostic daughters. For diesters, a benzonium fragment, formed by polyene elimination, was required for identification of the second fatty acid attached to the astaxanthin backbone. Parents were forced into [M + Na]+ ionization by addition of sodium acetate, and best signal-to-noise ratios were obtained in the 0.1 to 1.0mM range. This method was applied to fingerprinting astaxanthin esters in a crude H. pluvialis extract. Prior to MALDI-TOF/TOF-MS, the extract was fractionated by normal phase Flash chromatography to obtain fractions enriched in mono- and diesters and to remove pheophytin a, which compromised monoester signals. All 12 types of all-trans esterified esters found in LC were identified with MALDI-TOF/TOF-MS, with the exception of two minor monoesters.
Original languageEnglish
Pages (from-to)862-874
JournalJournal of Mass Spectrometry
Volume48
Issue number7
DOIs
Publication statusPublished - 2013

Keywords

  • tandem mass-spectrometry
  • desorption ionization maldi
  • fatty-acid esters
  • carotenoids
  • identification
  • microalgae

Fingerprint Dive into the research topics of 'Sodiation as a tool for enhancing the diagnostic value of MALDI-TOF/TOF-MS spectra of complex astaxanthin ester mixtures from Haematococcus pluvialis'. Together they form a unique fingerprint.

Cite this