Comparison of graphite-assisted laser desorption/ionization and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry for the analysis of pyrolysis liquids

Graphite-assisted laser desorption/ionization and matrix-assisted laser desorption/ionization fourier transform ion cyclotron resonance mass spectrometry (GALDI and MALDI-FT-ICR-MS) were applied in a comparative study for the analysis of various pyrolysis liquids. The aim of the study was the identification of differences in the ionization behavior and to determine if the ionization by GALDI is harder in comparison to MALDI. To obtain optimal results in terms of a high peak number, a high peak intensity and no peak splitting at the same time, an optimization of the operating parameters for positive-ion GALDI was performed. Moreover, a preparation technique for the analysis of pyrolysis liquids using positive-ion MALDI had to be developed. The applicability of the developed positive-ion GALDI and positive-ion MALDI methods was examined using selected pyrolysis liquids obtained from different raw materials. The comparison of the data sets demonstrates that a higher number of molecular formulas can be found using positive-ion GALDI and that higher molecular weight compounds can be ionized using positive-ion GALDI, if optimized parameters are applied. It could be shown that the additionally observed molecular formulas are no fragments or aggregates. (c) 2018 Elsevier B.V. All rights reserved.