A strategy for absolute quantitation of isomers using high performance liquid chromatography-ion mobility mass spectrometry and material balance principle

Differentiation of regioisomers of sulfobenzoic acid by traveling-wave ion mobility mass spectrometry

An ion mobility mass spectrometry (IM-MS) investigation using a Synapt G2 mass spectrometer was conducted to separate anions generated from the three regioisomers of sulfobenzoic acid. The results revealed that the differences in arrival time distributions (ATDs) were inadequate to differentiate the isomers unambiguously. However, the ATD profiles of the product ions, generated by fragmenting the respective mass-selected m/z 201 precursor ions in the Trap region of the three-compartment traveling-wave ion guide of the Synapt G2 mass spectrometer, were distinctly different, enabling definitive differentiation of the isomers. An arrival-time peak for an ion of m/z 157 resulting from the loss of CO2 from the respective precursors was common to all three mobilograms. However, only the profile recorded from the para-isomer exhibited a unique arrival-time peak for an ion of m/z 137, originating from an SO2 loss. Such a peak corresponding to an SO2 loss was absent in the ATD profiles of the ortho- and meta-isomers. Additionally, the mobilogram of the meta-isomer displayed a unique peak at 3.42 ms. Based on its product ion spectrum, this peak was attributed to the bisulfite anion (m/z 81; HSO3-). Previously, this meta-isomer specific m/z 81 ion had been proposed to originate from a two-step process involving the intermediacy of an m/z 157 ion formed by CO2 loss. However, our detailed tandem mass spectrometric experiments suggest that the m/z 81 is not a secondary product but rather an ion that originated from a direct elimination of a benzyne derivative from the m/z 201 precursor ion.

Applications of ion mobility-mass spectrometry in the chemical analysis in traditional Chinese medicines

离子淌度质谱(IM-MS)是一种将离子淌度分离与质谱分析相结合的新型分析技术。IM-MS的主要优势不仅是在质谱检测前提供了基于气相离子形状、大小、电荷数等因素的多一维分离,而且能够提供碰撞截面积、漂移时间等质谱信息进而辅助化合物鉴定。近年来,随着IM-MS技术的不断发展,该技术在中药化学成分分析中受到越来越多的关注。首先,IM-MS已成功应用于改善中药复杂成分尤其是同分异构体或等量异位素等成分的分离;其次,IM-MS可通过多重碎裂模式辅助高质量中药小分子质谱信息的获取;此外,IM-MS提供的高维质谱数据信息还可促进中药复杂体系多成分的整合分析。该文在对IM-MS分类和基本原理进行概述的基础上,从分离能力及分离策略、多重碎裂模式、多维质谱数据处理策略3个方面,重点综述了IM-MS在中药化学成分分析中的应用,以期为IM-MS在中药化学成分研究提供参考。

Simultaneous quantitative assays of 15 ginsenosides from 119 batches of ginseng samples representing 12 traditional Chinese medicines by ultra-high performance liquid chromatography coupled with charged aerosol detector

Despite the extensive consumption of ginseng, precise quality control of different ginseng products is highly challenging due to the containing of ginsenosides in common for different Panax species or different parts (e.g. root, leaf, and flower) of a same species. Herein we performed a comparative investigation of diverse ginseng products by simultaneously assaying 15 saponins (notoginsenoside R1, ginsenosides Rg1, -Re, -Rf, -Ra2, -Rb1, -Rc, -Ro, -Rb2, -Rb3, -Rd, 20(R)-ginsenoside Rg3, 24(R)-pseudoginsenoside F11, chikusetsusaponins IV, and -IVa) using an ultra-high-performance liquid chromatography/charged aerosol detector (UHPLC-CAD) approach. Twelve Panax-derived ginseng products (involving P. ginseng root, P. quinquefolius root, P. notoginseng root, Red ginseng, P. ginseng leaf, P. quinquefolius leaf, P. notoginseng leaf, P. ginseng flower, P. quinquefolius flower, P. notoginseng flower, P. japonicus root, and P. japonicus var. major root) were considered. Benefiting from the condition optimization, the baseline resolution of 15 ginsenosides was achieved on a CORTECS UPLC Shield RP18 column. This method was validated as specific, precise (0.81-1.94% intra-day variation; 0.86-2.35% inter-day variation), and accurate (recovery: 90.73-107.5%), with good linearity (R² > 0.999), high sensitivity (limit of detection: 0.02-0.21 μg; limit of quantitation: 0.04-0.42 μg) and sample stability (1.49-4.74%). Its application to 119 batches of ginseng samples unveiled vital information enabling the authentication of these different ginseng products. Detection of ginsenosides by CAD exhibited superiority over UV in sensitivity and the ability to monitor chromophore-free structures. Large-scale comparative studies by quantifying multiple markers provide methodological reference to the precise quality control of herbal medicine.