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The co-elution, pervasive isomers, and frequently occurring in-source fragmentation definitely hinder the comprehensive characterization of the multiple components from traditional Chinese medicine (TCM) by liquid chromatography/mass spectrometry. Herein, a dimension-enhanced strategy, by utilizing an ion mobility quadrupole time-of-flight mass spectrometer coupled to ultra-high performance liquid chromatography (UHPLC/IM-QTOF-MS) with the ability of offering four-dimensional information (retention time, Rt; drift time or collision cross section, CCS; accurate mass of precursors; and accurate MS2 product ions), is presented. Shuanghe Decoction (SHD) is a classic tonifying formula composed of nine herbs, however, little is known to its chemical complexity, hitherto. Good chromatographic separation was achieved on an HSS T3 column, and by the Vion™ IMS-QTOF high-resolution mass spectrometer, data-independent MSE and High-Definition MSE (HDMSE) in both the negative and positive electrospray ionization modes were employed for acquiring the collision-induced dissociation-MS2 data. A self-built database, including 642 known compounds, was established, which assisted to perform the automated peak annotation by UNIFI™. By reference to 55 compounds, totally 236 components were identified or tentatively characterized from SHD with 4D data recorded. The combination of negative and positive modes could yield more information complementary to structural elucidation. Compared with the conventional MSE, HDMSE exhibit of merits in the provision of CCS, better separation and detection those easily co-eluting components, and reduction of the false positives in the identification results. Conclusively, the combination of HDMSE acquisition, in-house library, and UNIFI-facilitated automated peak annotation, renders a potent approach dedicated to deconvoluting the chemical composition of complex systems like TCM formulae.

RATIONALE Kaixin San (KXS) is a prescription traditional Chinese medicine (TCM) with the effects of "tonifying the kidney and brain" and "improving memory". The volatile organic compounds (VOCs) in KXS could effectively improve senile dementia and depression, but only few studies have focused on the overall characterization of VOCs in KXS and the quantitative study of the main active components. METHODS We have developed a strategy to correlate the results from headspace gas chromatography/ion mobility spectrometry (HS-GC/IMS) and headspace gas chromatography/mass spectrometry (HS-GC/MS) for the comprehensive characterization of VOCs in KXS and the quantitative analysis of the main pharmacodynamic substances. RESULTS A totsal of 68 low molecular weight VOCs were identified in KXS by HS-GC/IMS at room temperature and atmospheric pressure; 117 VOCs were identified and 10 components (isocalamenediol, α-asarone, β-asarone, methyl eugenol, isoeugenol methyl ether, camphor, anethol, 2,4-di-tert-butylphol, linalool, asarylaldehyde) as the quality markers of KXS based on HS-GC/MS. CONCLUSIONS This results from this study provide a foundation for quality control, pharmacodynamic mechanism research and further development of KXS, and provides more convincing data supporting the VOCs of other natural products.

Kai-Xin-San (KXS) is a traditional Chinese medicine (TCM) formula containing four herbal medicines: Ginseng Radix Rhizoma, Polygalae Radix, Poria and Acori Tatarinowii Rhizoma. A large number of pharmacological studies in vitro and in vivo have shown that KXS is characterized by anti-depression, anti-Alzheimer's disease, anti-oxidation and other activities. However, the pharmacodynamic substance basis studies of KXS are hitherto quite limited. Here, KXS was identified and determined by ultra-performance liquid chromatography-quadrupole-Orbitrap mass spectrometry (UPLC-Q-Orbitrap MS) and gas chromatography-mass spectrometry (GC-MS). Firstly, the data-dependent acquisition mode (DDA) of UPLC-Q-Orbitrap MS combined with the inclusion list were used to collected the chemical composition. The chemical constituents of KXS were identified by local database on compound discoverer™ 3.1 software and Xcalibur 4.1 software. With the use of this approach, a total of 211 compounds were identified from KXS. Wherein 60 compounds were from Ginseng Radix Rhizoma, 40 compounds were from Poria, and 111 compounds were from Polygala Radix, respectively. Secondly, 105 volatile constituents were identified by GC-MS analysis, which were mainly derived from Acori Tatarinowii Rhizoma. Besides, an adjusted parallel reaction monitoring method was established and validated to quantify the seventeen major compounds in different herbal medicines of KXS, which were chosen as the benchmarked substances to evaluate the quality of KXS. In conclusion, this study provided a generally applicable strategy for global metabolite identification of the complicated components and determination of multi-component content in traditional Chinese medicines.

Rapid, non-destructive, accurate, and high-throughput screening of volatile ingredients plays an important role in the field of analysis. Gas chromatography–ion mobility spectrometry (GC–IMS) has the advantages of high separation efficiency, high sensitivity, no requirement for sample pretreatment and fast response, which are important for the nondestructive and rapid detection of volatile organic compounds (VOCs). This paper reviews the application of GC–IMS in the past 10 years. First, the working principle, experimental process, data processing methods, and advantages of GC–IMS are outlined and followed by the research progress in the use of GC–IMS in traditional Chinese medicine (TCM) detection, clinical research, food industry, environmental protection, polymer, and petrochemical analysis. Finally, the development trends in GC–IMS are summarized and presented, as well as the possible expansion areas of GC–IMS in the future.