Zhejiang Provincial Key Laboratory of Advanced Mass Spectrometry and Molecular Analysis, Institute of Mass Spectrometry, Ningbo University, Ningbo, 315211, PR China; School of Material Science and Chemical Engineering, Ningbo University, Ningbo, 315211, PR China.
Zhejiang Provincial Key Laboratory of Advanced Mass Spectrometry and Molecular Analysis, Institute of Mass Spectrometry, Ningbo University, Ningbo, 315211, PR China; Faculty of Electrical Engineering and Computer Science, Ningbo University, Ningbo, 315211, PR China.
Talanta. 2021 Aug 1;230:122348. doi: 10.1016/j.talanta.2021.122348. Epub 2021 Mar 30.
Carbohydrates are an indispensable part of early life evolution. The determination of their structures is a key step to analyze their critical roles in biological systems. A variation of composition, glycosidic linkage, and (or) configuration between carbohydrate isomers induces structure diversity and brings challenges for their structural determination. Ion mobility spectrometry (IMS), an emerging gas-phase ion separation technology, has been considered as a promising tool for performing carbohydrate structure elucidation. In this work, eight disaccharides were analyzed by trapped ion mobility spectrometry-mass spectrometry (TIMS-MS) in the negative ion mode as the complexed form of [M + X], where M = disaccharide, and X = Cl, Br, and I. As compared to the positive ion analysis of the selected disaccharide in a sodiated form, a reversal charge state provided the ability to eliminate or even reverse the collision cross section (CCS) difference between disaccharide isomers. By the combination of TIMS analysis and the calculation of density functional theory, the only observed two conformers of ions [lactulose + I] may result from different adduction sites for an iodide anion. Based on the comparison of different halogen adducts, the [M + I] ion form exhibited more powerful ability for isomeric disaccharide differentiation with an average resolution (R) of 1.17, which results in a 34.5% improvement as compared to the corresponding chloride adducts. This result indicates that the use of negative charge states, especially the complexation of an iodide anion, could be a supplemental strategy to commonly used positive ion analysis for carbohydrate separation.
碳水化合物是生命早期进化不可或缺的一部分。确定它们的结构是分析其在生物系统中关键作用的关键步骤。碳水化合物异构体之间组成、糖苷键和（或）构型的变化导致了结构多样性，并为其结构确定带来了挑战。离子淌度谱（IMS）是一种新兴的气相离子分离技术，已被认为是进行碳水化合物结构阐明的有前途的工具。在这项工作中，八种二糖通过负离子模式下的被困离子淌度谱-质谱（TIMS-MS）以[M + X]的复合物形式进行分析，其中 M = 二糖，X = Cl、Br 和 I。与选择的二糖在钠离子形式下的正离子分析相比，反转电荷状态提供了消除甚至反转二糖异构体之间碰撞截面（CCS）差异的能力。通过 TIMS 分析与密度泛函理论计算的结合，仅观察到离子[lactulose + I]的两种构象可能是由于碘阴离子的不同加成位点所致。基于不同卤素加合物的比较，[M + I]离子形式表现出更强的区分异构二糖的能力，平均分辨率（R）为 1.17，与相应的氯化物加合物相比提高了 34.5%。该结果表明，使用负电荷态，特别是碘阴离子的络合，可以作为碳水化合物分离常用的正离子分析的补充策略。
