Characterization of microalgal lipid feedstock by direct-infusion FT-ICR mass spectrometry

We demonstrate the utility of direct-infusion FT-ICR mass spectrometry for comprehensive characterization of microalgal lipid extracts. High mass accuracy and mass resolving power combined with Kendrick mass sorting and isotopic fine structure analysis enable unambiguous determination of elemental composition for up to several thousand individual compounds present in these extracts. Elemental compositions are matched to an in-house assembled lipid database derived from Lipid Maps (Nature, Lipidomics Gateway) for tentative molecular identification and subsequent tandem mass measurement of select members of each Kendrick series confirms molecular assignments. These data may be used to highlight trends in lipid class distribution as well as changes in individual lipid species to enable comparison of lipid extraction techniques, comparison of algal species and analysis of variable process or growth conditions, for example. With this approach we identify a novel sulfate lipid class for Nannochloropsis salina and Scenedesmus obliquus and show that these compounds form alky-diols upon hydrolysis (which have previously been reported to have a role in algaenan synthesis from Eustigmatophyceae). (c) 2012 Elsevier B.V. All rights reserved.