Characterization of organosolv switchgrass lignin by using high performance liquid chromatography/ high resolution tandem mass spectrometry using hydroxide-doped negative-ion mode electrospray ionization

Lignin is an aromatic biopolymer that may yield valuable chemicals currently obtained solely from petroleum. However, extraction of lignin by using traditional methods, such as organosolv extraction, produces very complex mixtures. Molecular level characterization of the major components is essential to be able to rationally tailor methodology for the conversion of these mixtures to transportation fuel and valuable chemicals. In this study, high performance liquid chromatography/high resolution tandem mass spectrometry (HPLC/MSn) was used to obtain molecular weight, elemental composition and structural information for the major components in an organosolv lignin sample. HPLC/MSn coupled with hydroxide-doped electrospray ionization was used to identify the structures of the major components by using a Thermo Scientific linear quadrupole ion trap-Fourier transform ion cyclotron resonance hybrid mass spectrometer (LQIT/FT-ICR). The results reported here demonstrate that the major products of organosolv extraction are low molecular weight compounds, including monomeric and dimeric lignin units, with various functionalities.