Starke Ines, Fürstenberg Sylvia, Thomas Steffen
Institute of Chemistry, University of Potsdam, Potsdam, Germany.
Rapid Commun Mass Spectrom. 2024 Dec 15;38(23):e9899. doi: 10.1002/rcm.9899.
The 1, 2-unsaturated derivatives of (1-4) linked disaccharides serve as versatile building blocks for synthesizing biologically active compounds. Distinguishing between four pairs of stereoisomers in mixtures presents a challenging task. In this study, disaccharide derivatives are analyzed as alkali metal adducts using electrospray ionization tandem mass spectrometry (ESI-MS/MS), both as individual compounds and in mixtures by ion mobility mass spectrometry (IMS).
Electrospray ionization (ESI) in combination with tandem mass spectrometry (MS/MS) in positive mode was employed to differentiate lithium adduct ions of hexa-acetyl/hexa-benzyl-D-lactals, and hexa-acetyl/hexa-benzyl-D-maltals, along with their corresponding 2-C-branched malonates. The high resolving power of trapped ion mobility spectrometry (TIMS) with the imeX™ functionality rapidly identified different metal adducts (Li, Na, Cs) as individual isomers and separated mixtures of stereoisomers. The measured collisional cross section (CCS) values were analyzed in relation to predicted CCS values.
MS/MS spectra of the [M + Li] ions of glycal disaccharide analogues exhibited typical cross-ring and glycosidic bond cleavages. Collision-induced dissociation (CID) spectra provided insights into their fragmentation behavior, allowing differentiation of (1-4) linked disaccharides. TIMS technology delivered adjustable ion mobility resolution for suitable separation of the four sets of stereo isomeric compounds. However, accurately predicting CCS values to differentiate between respective isomeric pairs using the SigmaCCS program for sodium adducts is only partially achievable.
ESI CID spectra of [M + Li] adduct ions for individual glycal disaccharide analogues facilitate the discrimination between alpha and beta (1-4) linked unsaturated disaccharides and their 2-C-branched analogues. Through optimized experimental conditions, complete baseline ion mobility separation of stereoisomer pairs of the Cs adducts is achieved.
（1-4）连接的二糖的1,2-不饱和衍生物是合成生物活性化合物的通用构建模块。区分混合物中的四对对映异构体是一项具有挑战性的任务。在本研究中，使用电喷雾电离串联质谱（ESI-MS/MS）将二糖衍生物作为碱金属加合物进行分析，通过离子淌度质谱（IMS）对其单独化合物和混合物进行分析。
采用正模式下的电喷雾电离（ESI）与串联质谱（MS/MS）相结合的方法，区分六乙酰基/六苄基-D-乳糖醛和六乙酰基/六苄基-D-麦芽醛及其相应的2-C-支链丙二酸酯的锂加合离子。具有imeX™功能的阱式离子淌度光谱（TIMS）的高分辨率能够快速识别不同的金属加合物（Li、Na、Cs）作为单独的异构体，并分离对映异构体混合物。将测得的碰撞截面（CCS）值与预测的CCS值进行分析。
糖基二糖类似物的[M + Li]离子的MS/MS光谱显示出典型的跨环和糖苷键裂解。碰撞诱导解离（CID）光谱提供了对其碎片化行为的见解，从而能够区分（1-4）连接的二糖。TIMS技术提供了可调节的离子淌度分辨率，以适当地分离四组立体异构化合物。然而，使用SigmaCCS程序对钠加合物准确预测CCS值以区分各对映异构体对仅部分可行。
单个糖基二糖类似物的[M + Li]加合离子的ESI CID光谱有助于区分α和β（1-4）连接的不饱和二糖及其2-C-支链类似物。通过优化实验条件，实现了Cs加合物对映异构体对的完全基线离子淌度分离。
