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

Abstract

Rationale Effective analytical techniques are needed to characterize lignin products for the generation of renewable carbon sources. Application of matrix‐assisted laser desorption/ionization (MALDI) in lignin analysis is limited because of poor ionization efficiency. In this study, we explored the potential of cationization along with a 2,5‐dihydroxyacetophenone (DHAP) matrix to characterize model lignin oligomers. Methods Synthesized lignin oligomers were analyzed using the developed MALDI method. Two matrix systems, DHAP and α‐cyano‐4‐hydroxycinnamic acid (CHCA), and three cations (lithium, sodium, silver) were evaluated using a Bruker UltraFlextreme time‐of‐flight mass spectrometer. Instrumental parameters, cation concentration, matrix, sample concentrations, and sample spotting protocols were optimized for improved results. Results The DHAP/Li+ combination was effective for dimer analysis as lithium adducts. Spectra from DHP and ferric chloride oligomers showed improved signal intensities up to decamers (m/z 1823 for the FeCl3 system) and provided insights into differences in the oligomerization mechanism. Spectra from a mixed DHP oligomer system containing H, G, and S units showed contributions from all monolignols within an oligomer level (e.g. tetramer level). Conclusions The DHAP/Li+ method presented in this work shows promise to be an effective analytical tool for lignin analysis by MALDI and may provide a tool to assess lignin break‐down efforts facilitating renewable products from lignin.

Application of Carbon Matrices to Screening Pentacylic Triterpenoids in Plant Feedstock by MALDI Mass Spectrometry

“…Mass spectra of PCTs recorded on the addition of lithium, sodium, and potassium salt solutions to test samples were investigated ( Table 2). The level of concentrations of cationizing agents and their ratio to analyte concentrations were chosen based on the published data on the study of plant samples by MALDI mass spectrometry [27].…”

An Eco-Sustainable Stabilization of Clayey Road Subgrades by Lignin Treatment: An Overview and a Comparative Experimental Investigation

“…LDI-MS experiments indicated that the presence of specific peaks, the way in which the peaks were grouped, and the global shape of the spectrum reflected the global structure of lignin oligomers [73]. LDI-MS analysis revealed a wide mass distribution of lignin oligomers [74,75]. However, the experimental conditions allowed the analysis of monocharged species with low fragmentation.…”

Lignin Functionalization for the Production of Novel Materials

“…Lignin molecule weight has also been investigated by mass spectroscopy, particularly matrix-assisted laser desorption/ ionization mass spectrometry (MALDI-MS). However, the heterogeneous nature of lignin and the challenge of ionizing all fractions equally severely limit the use of this technique for accurate characterization of lignin [32].…”