Chemical diversity of lignin degradation products revealed by matrix-optimized MALDI mass spectrometry
Lignin is the most abundant natural resource of aromatic moieties and the second most abundant natural biopolymer. Analytical techniques that obtain as much information as possible on the exact structural content of lignin species are essential for developing efficient processes that transform highly complex lignin wastes into value chemicals and biofuels. For mass spectrometric analysis of lignin samples, usually electrospray ionization, atmospheric pressure chemical ionization, or atmospheric pressure photoionization are used as ionization techniques. Matrix-assisted laser desorption/ionization (MALDI) is less frequently applied but offers a much more rapid screening option for lignin mixtures. In this study, we compared several common MALDI matrices for analysis of alkali lignin and discovered that different chemical matrices exhibited very different ionization efficiencies and selectivity with respect to the structures of the lignin-related compounds as well as the presence of heteroatoms. Importantly, the results highlight that the choice of matrix strongly determines the analytical coverage of molecular species in the complex lignin degradation mixtures.
KeywordsLignin degradation products Mass spectrometry MALDI Chemical matrices
The manuscript was written through contributions of all authors.
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Conflict of interest
The authors declare that they have no competing interests.
- 8.Qi Y, Volmer DA. Rapid mass spectral fingerprinting of complex mixtures of decomposed lignin: data-processing methods for high-resolution full-scan mass spectra. Rapid Commun Mass Spectrom accepted. 2018. https://doi.org/10.1002/rcm.8254.
- 9.Bozell JJ, O’Lenick CJ, Warwick S. Biomass fractionation for the biorefinery: heteronuclear multiple quantum coherence-nuclear magnetic resonance investigation of lignin isolated from solvent fractionation of switchgrass. J Agric Food Chem. 2011;59:9232–42. https://doi.org/10.1021/jf201850b.CrossRefGoogle Scholar
- 14.Brinkmann K, Blaschke L, Polle A Comparison of different methods for lignin determination as a basis for calibration of near-infrared reflectance spectroscopy and implications of lignoproteins. J Chem Ecol 28:2483–2501 . doi: https://doi.org/10.1023/A:1021484002582.
- 19.Jarrell TM, Marcum CL, Sheng H, Owen BC, O’Lenick CJ, Maraun H, et al. Characterization of organosolv switchgrass lignin by using high performance liquid chromatography/high resolution tandem mass spectrometry using hydroxide-doped negative-ion mode electrospray ionization. Green Chem. 2014;16:2713–27. https://doi.org/10.1039/C3GC42355G.CrossRefGoogle Scholar
- 20.Owen BC, Haupert LJ, Jarrell TM, Marcum CL, Parsell TH, Abu-Omar MM, et al. High-performance liquid chromatography/high-resolution multiple stage tandem mass spectrometry using negative-ion-mode hydroxide-doped electrospray ionization for the characterization of lignin degradation products. Anal Chem. 2012;84:6000–7. https://doi.org/10.1021/ac300762y.CrossRefGoogle Scholar
- 23.Cho Y, Na J-G, Nho N-S, Kim S, Kim S. Application of saturates, aromatics, resins, and asphaltenes crude oil fractionation for detailed chemical characterization of heavy crude oils by Fourier transform ion cyclotron resonance mass spectrometry equipped with atmospheric pressure photoionization. Energy Fuel. 2012;26:2558–65. https://doi.org/10.1021/ef201312m.CrossRefGoogle Scholar
- 24.Barrow MP, Witt M, Headley JV, Peru KM. Athabasca oil sands process water: characterization by atmospheric pressure photoionization and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Anal Chem. 2010;82:3727–35. https://doi.org/10.1021/ac100103y.CrossRefGoogle Scholar
- 26.Headley JV, Peru KM, Barrow MP. Mass spectrometric characterization of naphthenic acids in environmental samples: a review. Mass Spectrom Rev. 28:121–34. https://doi.org/10.1002/mas.20185.
- 32.Kosyakov DS, Anikeenko EA, Ul’yanovskii NV, Khoroshev OY, Shavrina IS, Gorbova NS. Ionic liquid matrices for MALDI mass spectrometry of lignin. Anal Bioanal Chem. 2018. https://doi.org/10.1007/s00216-018-1353-7.
- 33.Albishi T, Mikhael A, Shahidi F, Fridgen TD, Delmas M, Banoub J. Top-down lignomic matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry analysis of lignin oligomers extracted from date palm wood. Rapid Commun Mass Spectrom. 2019;33:539–60. https://doi.org/10.1002/rcm.8368.CrossRefGoogle Scholar
- 34.Bowman AS, Asare SO, Lynn BC. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis for characterization of lignin oligomers using cationization techniques and 2,5-dihydroxyacetophenone (DHAP) matrix. Rapid Commun Mass Spectrom. 2019;33:811–9. https://doi.org/10.1002/rcm.8406.CrossRefGoogle Scholar
- 41.Bennett KL, Kussmann M, Mikkelsen M, Roepstorff P, Björk P, Godzwon M, et al. Chemical cross-linking with thiol-cleavable reagents combined with differential mass spectrometric peptide mapping—a novel approach to assess intermolecular protein contacts. Protein Sci. 2000;9:1503–18. https://doi.org/10.1110/ps.9.8.1503.CrossRefGoogle Scholar
- 42.Huwiler KG, Mosher DF, Vestling MM. Optimizing the MALDI-TOF-MS observation of peptides containing disulfide bonds. J Biomol Tech. 2003;14:289–97.Google Scholar
- 45.Lou X, de Waal BFM, van Dongen JLJ, Vekemans JAJM, Meijer EW. A pitfall of using 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene] malononitrile as a matrix in MALDI TOF MS: chemical adduction of matrix to analyte amino groups. J Mass Spectrom. 2010;45:1195–202. https://doi.org/10.1002/jms.1814.CrossRefGoogle Scholar
- 46.Purcell JM, Merdrignac I, Rodgers RP, Marshall AG, Gauthier T, Guibard I. Stepwise structural characterization of asphaltenes during deep hydroconversion processes determined by atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Energy Fuel. 2010;24:2257–65. https://doi.org/10.1021/ef900897a.CrossRefGoogle Scholar