BioEnergy Research

, Volume 8, Issue 4, pp 1962–1972

Temperature-Dependent Lipid Conversion and Nonlipid Composition of Microalgal Hydrothermal Liquefaction Oils Monitored by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

  • Nilusha Sudasinghe
  • Harvind Reddy
  • Nicholas Csakan
  • Shuguang Deng
  • Peter Lammers
  • Tanner Schaub
Article

DOI: 10.1007/s12155-015-9635-9

Cite this article as:
Sudasinghe, N., Reddy, H., Csakan, N. et al. Bioenerg. Res. (2015) 8: 1962. doi:10.1007/s12155-015-9635-9

Abstract

We illustrate a detailed compositional characterization of hydrothermal liquefaction (HTL) oils derived from two biochemically distinct microalgae, Nannochloropsis gaditana and Chlorella sp. (DOE 1412), for a range of reaction temperature as observed by high-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The unique capability to unequivocally derive molecular formulae directly from FT-ICR MS-measured mass-to-charge ratio (for several thousand compounds in each oil) shows that lipids are completely reacted/converted for any reaction temperature above 200 °C and reveals the formation of nonlipid reaction products with increasing temperature. Specifically, lipid-rich oil is obtained at low reaction temperature (<225 °C) for both microalgal strains. For positive ion mode, the major lipid components in Chlorella sp. and N. gaditana HTL oils are betaine lipids and acylglycerols, respectively. Acidic species in the HTL oils (observed by negative ion mode) are dominated by free fatty acids (FFA) regardless of reaction temperature. HTL oils obtained at higher temperatures (≥225 °C) are composed of a variety of basic nitrogen- and oxygen-containing compounds that originate from protein and carbohydrate degradation at elevated temperature. Similar structural features are observed for the abundant nitrogen heterocyclics between the two strains with slightly lower carbon number for Chlorella sp., overall.

Keywords

Nannochloropsis Chlorella Hydrothermal liquefaction Lipids FT-ICR MS Mass spectrometry 

Supplementary material

12155_2015_9635_MOESM1_ESM.pdf (37 kb)
Online Resource 1Positive-ion ESI MS2 spectrum of 16:0 monoacylglyceryl-N,N,N-trimethylhomoserine (MGTS) (top) and MS3 spectrum of 456 Da ion from Chlorella sp. HTL oil produced at 180 °C (PDF 36 kb)
12155_2015_9635_MOESM2_ESM.pdf (48 kb)
Online Resource 2Positive-ion ESI MS2 spectrum of 16:0/20:5 diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) (top) and 16:0/16:1 DGTS (bottom) from Chlorella sp. HTL oil produced at 180 °C (PDF 48 kb)
12155_2015_9635_MOESM3_ESM.pdf (127 kb)
Online Resource 3Positive-ion ESI MS2 spectrum of 16:0/16:1 diacylglycerol (DAG) (top) and 16:0/16:0/16:1 TAG (bottom) from N. gaditana HTL oil produced at 180 °C (PDF 126 kb)
12155_2015_9635_MOESM4_ESM.pdf (43 kb)
Online Resource 4Acid- and base-catalyzed FAME profiles for N. gaditana (top) and Chlorella sp. (bottom) biomass (PDF 42 kb)
12155_2015_9635_MOESM5_ESM.pdf (44 kb)
Online Resource 5Negative-ion ESI FT-ICR MS abundance-contoured plots of DBE versus carbon number for oxidized fatty acids observed for Chlorella sp. (left) and N. gaditana (right) HTL oils produced at 300 °C (PDF 43 kb)
12155_2015_9635_MOESM6_ESM.pdf (39 kb)
Online Resource 6Negative-ion ESI MS2 spectrum of the predominant O5 sulfate lipid (C32H65O5S1) (top) and O4 sulfate lipid (C32H63O4S1) (bottom) from N. gaditana HTL oil produced at 180 °C (PDF 38 kb)
12155_2015_9635_MOESM7_ESM.pdf (29 kb)
Online Resource 7Negative-ion ESI MS2 spectrum of 16:0 sulfoquinovosyl monoacylglycerol (SQMG) from Chlorella sp. HTL oil produced at 180 °C (PDF 29 kb)

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Nilusha Sudasinghe
    • 1
  • Harvind Reddy
    • 2
    • 4
  • Nicholas Csakan
    • 3
    • 5
  • Shuguang Deng
    • 2
  • Peter Lammers
    • 3
    • 5
  • Tanner Schaub
    • 1
  1. 1.Chemical Analysis and Instrumentation Laboratory, College of Agricultural, Consumer and Environmental SciencesNew Mexico State UniversityLas CrucesUSA
  2. 2.Department of Chemical and Materials EngineeringNew Mexico State UniversityLas CrucesUSA
  3. 3.Energy Research LaboratoryNew Mexico State UniversityLas CrucesUSA
  4. 4.Tucker Energy Services, Inc.McAlesterUSA
  5. 5.Arizona Center for Algal Technology and InnovationArizona State UniversityTempeUSA

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