The capability to characterize lignin, lignocellulose, and their degradation products is essential for the development of new renewable feedstocks. Electrospray ionization high-resolution time-of-flight mass spectrometry (ESI-HR TOF-MS) method was developed expanding the lignomics toolkit while targeting the simultaneous detection of low and high molecular weight (MW) lignin species. The effect of a broad range of electrolytes and various ionization conditions on ion formation and ionization effectiveness was studied using a suite of mono-, di-, and triarene lignin model compounds as well as kraft alkali lignin. Contrary to the previous studies, the positive ionization mode was found to be more effective for methoxy-substituted arenes and polyphenols, i.e., species of a broadly varied MW structurally similar to the native lignin. For the first time, we report an effective formation of multiply charged species of lignin with the subsequent mass spectrum deconvolution in the presence of 100 mmol L⁻¹ formic acid in the positive ESI mode. The developed method enabled the detection of lignin species with an MW between 150 and 9000 Da or higher, depending on the mass analyzer. The obtained M _n and M_w values of 1500 and 2500 Da, respectively, were in good agreement with those determined by gel permeation chromatography. Furthermore, the deconvoluted ESI mass spectrum was similar to that obtained with matrix-assisted laser desorption/ionization (MALDI)-HR TOF-MS, yet featuring a higher signal-to-noise ratio. The formation of multiply charged species was confirmed with ion mobility ESI-HR Q-TOF-MS.

中文翻译：

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电喷雾电离与高分辨率质谱法作为Lignomics的工具：木质素质谱解卷积

表征木质素，木质纤维素及其降解产物的能力对于开发新型可再生原料至关重要。开发了电喷雾电离高分辨率飞行时间质谱（ESI-HR TOF-MS）方法，扩展了组学工具包，同时针对低分子量和高分子量（MW）木质素物质的同时检测。使用一套单，二和三芳烃木质素模型化合物以及牛皮纸碱木质素研究了各种电解质和各种电离条件对离子形成和电离效率的影响。与先前的研究相反，发现正电离模式对于甲氧基取代的芳烃和多酚（即，结构上与天然木质素相似的种类繁多的MW物种）更有效。正ESI模式下的^-1甲酸。所开发的方法能够检测分子量在150至9000 Da或更高之间的木质素，具体取决于质量分析仪。分别获得的1500和2500 Da的M _n和M _w值与通过凝胶渗透色谱法测定的M _n和M _w值非常一致。此外，解卷积的ESI质谱与通过基质辅助激光解吸/电离（MALDI）-HR TOF-MS获得的质谱相似，但具有更高的信噪比。通过离子迁移率ESI-HR Q-TOF-MS确认了多电荷物质的形成。