Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA.
Anal Chem. 2011 Sep 1;83(17):6722-30. doi: 10.1021/ac2013527. Epub 2011 Aug 3.
Imaging applied toward lignocellulosic materials requires high molecular specificity to map specific compounds within intact tissue. Although secondary ionization mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) with a single stage of MS have been used to image lignocellulosic biomass, the complexity of the plant tissue requires tandem MS, which limits the interpretation of simple MS. MALDI linear ion trap (LIT) tandem MS offers the high molecular specificity needed for lignocellulosic analyses. MALDI-LIT MS analyses of cellulose and xylan (hemicellulose) standards were performed to determine mass-to-charge ratios and fragmentation pathways for identification of these compounds in intact tissue. The MALDI-LIT-MS images of young Populus wood stem showed even distribution of both cellulose and hemicellulose ions; in contrast, the tandem MS images of cellulose and hemicellulose generated by plotting characteristic fragment ions resulted in drastically different images. This demonstrates that isobaric ions are present during MALDI-LIT-MS analyses of wood tissue and tandem MS is necessary to distinguish between isobaric species for selective imaging of carbohydrates in biomass.
成像应用于木质纤维素材料需要高的分子特异性来绘制完整组织内的特定化合物。虽然二次离子质谱（SIMS）和基质辅助激光解吸/电离质谱（MALDI-MS）与单级 MS 已被用于成像木质纤维素生物质，但植物组织的复杂性需要串联 MS，这限制了简单 MS 的解释。MALDI 线性离子阱（LIT）串联 MS 为木质纤维素分析提供了所需的高分子特异性。进行了纤维素和木聚糖（半纤维素）标准品的 MALDI-LIT 串联 MS 分析，以确定质荷比和碎片途径，用于鉴定完整组织中的这些化合物。年轻的杨树木质茎的 MALDI-LIT-MS 图像显示了纤维素和半纤维素离子的均匀分布；相比之下，通过绘制特征碎片离子生成的纤维素和半纤维素的串联 MS 图像导致了截然不同的图像。这表明在木质组织的 MALDI-LIT-MS 分析过程中存在等质荷比离子，并且需要串联 MS 来区分等质荷比物种，以便对生物质中的碳水化合物进行选择性成像。
