Triacylglycerol profiling of microalgae strains for biofuel feedstock by liquid chromatography–high-resolution mass spectrometry

• Published in: Analytical and bioanalytical chemistry 2011-11, Vol.401 (8), p.2609-2616
• Main Authors: MacDougall, Karen M., McNichol, Jesse, McGinn, Patrick J., O’Leary, Stephen J. B., Melanson, Jeremy E.
• Format: Article
• Language: English
• Subjects: Algae; Analytical Chemistry; Biochemistry; Biofuels - analysis; Biosynthesis; Botryococcus braunii; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chromatographic methods and physical methods associated with chromatography; Chromatography; Chromatography, High Pressure Liquid - methods; Exact sciences and technology; Fatty acids; Food Science; Fuels; Gas chromatographic methods; Laboratory Medicine; Lipids; Liquids; Mass Spectrometry - methods; Microalgae - chemistry; Monitoring/Environmental Analysis; Original Paper; Other chromatographic methods; Properties; Scenedesmus obliquus; Spectrometric and optical methods; Strain; Tags; Triacylglycerols; Triglycerides; Triglycerides - analysis; Triglycerides - chemistry; Triglycerides - isolation & purification
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-011-5376-6

Biofuels from photosynthetic microalgae are quickly gaining interest as a viable carbon-neutral energy source. Typically, characterization of algal feedstock involves breaking down triacylglycerols (TAG) and other intact lipids, followed by derivatization of the fatty acids to fatty acid methyl esters prior to analysis by gas chromatography (GC). However, knowledge of the intact lipid profile could offer significant advantages for discovery stage biofuel research such as the selection of an algal strain or the optimization of growth and extraction conditions. Herein, lipid extracts from microalgae were directly analyzed by ultra-high pressure liquid chromatography–mass spectrometry (UHPLC-MS) using a benchtop Orbitrap mass spectrometer. Phospholipids, glycolipids, and TAGs were analyzed in the same chromatographic run, using a combination of accurate mass and diagnostic fragment ions for identification. Using this approach, greater than 100 unique TAGs were identified over the six algal strains studied and TAG profiles were obtained to assess their potential for biofuel applications. Under the growth conditions employed, Botryococcus braunii and Scenedesmus obliquus yielded the most comprehensive TAG profile with a high abundance of TAGs containing oleic acid. Figure Optical microscope image of Botryococcus braunii and high resolution mass spectrum of triacylglycerol 28:2/18:1/18:1 (inset)