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首页> 外文期刊>Journal of mass spectrometry: JMS >Anomeric discrimination and rapid analysis of underivatized lactose, maltose, and sucrose in vegetable matrices by U-HPLC - ESI-MS/MS using porous graphitic carbon
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Anomeric discrimination and rapid analysis of underivatized lactose, maltose, and sucrose in vegetable matrices by U-HPLC - ESI-MS/MS using porous graphitic carbon

机译：U-HPLC-ESI-MS / MS使用多孔石墨碳对蔬菜基质中未衍生的乳糖，麦芽糖和蔗糖进行端粒识别和快速分析

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摘要

Lactose intolerance is a common condition caused by intestinal lactase deficiency, and a lactose-free diet represents the simplest way to avoid gastrointestinal symptoms. The emerging use of dietary supplements requires analytical tools that are capable of assessing these analytes, particularly for those based on dry herbal extracts that contain lactose together with maltose and sucrose, because of cross-contamination and/or deliberate addition as excipient. Electrospray ionization mass spectrometry (ESI-MS) and MS/MS are valuable detection methods for underivatized disaccharides; however, the absence of distinctive ions and collision-induced dissociation (CID) fragmentation patterns does not allow discrimination of stereoisomers without good chromatographic resolution. We developed an ultrahigh performance liquid chromatography-ESI (U-HPLC-ESI) approach, based on porous graphitic carbon (PGC) columns, working at 5 °C to separate and detect the disaccharides in their anomeric forms as formate adducts obtained directly in-column by eluting with formate buffer/acetonitrile gradient mixtures. Using a Paul trap, we monitored the adducts [M + HCOO]~- at m/z 387 in ESI negative mode (MS ~1) as well as the CID fragment ion [M - H]~- at m/z 341 (MS~2) and used MS~3 fragment ions at m/z 178 and 161 to confirm disaccharides identity in complex vegetable matrices. Complete resolution of lactose α- and β-anomers, maltose α- and β-anomers, and sucrose was obtained with R ≥ 2.0 for all peaks and selectivity α = 1.2 between α- and β-anomers of lactose. The limits of detection were in the range of 3-7 μg/l (ppb) for the target disaccharides. Because of the rapidity and good anomeric discrimination, the described method represents an alternative tool to investigate the mutarotation phenomenon for reducing disaccharides.
机译：乳糖不耐症是由肠道乳糖酶缺乏症引起的常见疾病，无乳糖饮食是避免胃肠道症状的最简单方法。膳食补充剂的新兴用途要求分析工具能够评估这些分析物，特别是对于那些基于乳糖，麦芽糖和蔗糖以及乳糖的干草药提取物的分析物，因为它们会交叉污染和/或故意添加作为赋形剂。电喷雾电离质谱（ESI-MS）和MS / MS是衍生化未衍生二糖的有价值的检测方法。然而，缺乏独特的离子和碰撞诱导的离解（CID）碎片模式无法在没有良好色谱分离度的情况下区分立体异构体。我们开发了一种基于多孔石墨碳（PGC）色谱柱的超高效液相色谱-ESI（U-HPLC-ESI）方法，在5°C下工作，以分离和检测其端基异构形式的二糖，直接从中获得甲酸盐加合物。用甲酸缓冲液/乙腈梯度混合物洗脱色谱柱。使用Paul阱，我们以m / z 387的ESI负离子模式（MS〜1）监测了加合物[M + HCOO]〜-，以及m / z 341的CID碎片离子[MH]〜-（ MS〜2），并使用m〜z 178和161的MS〜3碎片离子来确认复杂蔬菜基质中的二糖身份。乳糖α-和β-异头异构体，麦芽糖α-和β-异头异构体以及蔗糖的所有峰均得到完全拆分，所有峰的R≥2.0，乳糖α-和β-异头异构体之间的选择性α= 1.2。目标二糖的检出限在3-7μg/ l（ppb）范围内。由于其快速性和良好的端基异构性，所描述的方法代表了一种替代工具，用于研究减少二糖的突变现象。

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