Mischnick Petra, Schleicher Sarah
Institute of Food Chemistry, Technische Universität Braunschweig, Schleinitzstr. 20, 38106, Braunschweig, Germany.
Anal Bioanal Chem. 2024 Apr;416(10):2527-2539. doi: 10.1007/s00216-024-05224-w. Epub 2024 Mar 4.
Ion mobility mass spectrometry (ESI-tims-ToF-MS, syringe pump infusion) has been applied to glucose and oligosaccharide ethers derived from hydroxyethyl-methyl celluloses (HEMC) and hydroxyethyl celluloses (HEC) after permethylation and partial depolymerization: by hydrolysis without or with subsequent reductive amination with m-amino benzoic acid (mABA) or by reductive cleavage. As model compounds without tandem substitution methoxyethylated methylcellulose was used. Regioisomeric glucose ethers were separated according to their ion mobility, and positions of substitution could be assigned. Glucose ethers including isomers with tandem substitution showed additional signals with a smaller collision cross-section (CCS) than core-substituted isomers. Positional isomers of cellobiose ethers were only partly resolved due to too high complexity but showed a characteristic fingerprint that might allow classifying samples. Relative intensities of signals of glucose ether isomers could only be quantified in case of ABA derivatives with its fixed charge, while sodium adducts of methoxyethyl ethers showed an influence of the MeOEt position on ion yield. Results were in very good agreement with reference analysis. [M + Na] adducts of α- and β-anomers of glucose derivatives were separated in IM, complicating position assignment. This could be overcome by reductive cleavage of the permethylated HE(M)C yielding 1,5-anhydroglucitol-terminated oligosaccharides, showing the best resolved fingerprints of the cellobiose ethers of a particular cellulose ether. With this first application of ion mobility MS to the analysis of complex cellulose ethers, the promising potential of this additional separation dimension in mass spectrometry is demonstrated and discussed.
离子淌度质谱（电喷雾-淌度-飞行时间质谱，注射泵进样）已应用于经全甲基化和部分解聚后的羟乙基甲基纤维素（HEMC）和羟乙基纤维素（HEC）衍生的葡萄糖和寡糖醚：通过水解，无论有无随后用间氨基苯甲酸（mABA）进行还原胺化或通过还原裂解。使用了没有串联取代的甲氧基乙基化甲基纤维素作为模型化合物。区域异构的葡萄糖醚根据其离子淌度进行分离，并且可以确定取代位置。包括具有串联取代的异构体的葡萄糖醚显示出比核心取代异构体具有更小碰撞截面（CCS）的额外信号。由于过于复杂，纤维二糖醚的位置异构体仅部分得到分离，但显示出可能允许对样品进行分类的特征指纹。仅在具有固定电荷的ABA衍生物的情况下，葡萄糖醚异构体信号的相对强度才可以定量，而甲氧基乙基醚的钠加合物显示出MeOEt位置对离子产率的影响。结果与参考分析非常吻合。葡萄糖衍生物的α-和β-端基异构体的[M + Na]加合物在离子淌度中被分离，这使位置分配变得复杂。这可以通过对全甲基化的HE（M）C进行还原裂解来克服，得到以1,5-脱水葡萄糖醇结尾的寡糖，显示出特定纤维素醚的纤维二糖醚的最佳分辨指纹。通过离子淌度质谱在复杂纤维素醚分析中的首次应用，证明并讨论了质谱中这一额外分离维度的巨大潜力。
