Chemical Profiling of Peucedani Radix by Achiral-chiral Liquid Chromatography-Predictive Multiple Reaction Monitoring
复杂，而且常含有大量对映异构体，且对映异构体之间的含量常存在差异。本研究以中药前胡为例，建立了非手性-手性色谱-预测多反应监测法（Achiral-chiral LC-predictive MRM），实现了化学成分的化学选择性和立体选择性分析。非手性-手性色谱直接耦联系统结合了RP-C18色谱柱的高效分离能力以及手性色谱柱的立体选择性分离优势，有效避免了中心切割非手性-手性二维液相构造复杂、精密度差等缺陷。采用小内径核壳型RP-C18色谱柱作为前端化学分离柱，实现了结构类似香豆素的高效化学选择性分离；通过在手性柱前引入稀释泵，优化适用于手性选择性分离的洗脱程序；采用反相大内径AD-RH手性色谱柱，实现了对映异构体的手性拆分。采用预测多反应监测模式实现化学成分的高灵敏度检出，并利用增强子离子扫描模式采集各色谱峰的二级质谱，进行结构确证。从前胡中鉴定出61种化学成分，其中包括11对对映异构体。Achiral-chiral LC-predictive MRM为含有对映异构体的中药及其它复杂样品的深入定性和定量分析提供了可靠的方法。
Peucedani radix and other herbal medicines are not only complex in chemical composition, but also often contain a large number of enantiomers, and there are often differences in content of enantiomers. In this work, a new analytical platform namely achiral-chiral liquid chromatography (LC)-predictive multiple reaction monitoring was firstly configured for chemo- and enantio-selective separation of the components in Peucedani Radix, a well-known herbal medicine. Serially coupled achiral LC and chiral LC integrated the robust separation potential of RP-C18 column along with the enantio-separation advantage from chiral column, thus addressing the disadvantages of heart-cutting achiral-chiral two dimensional LC in terms of sophisticated instrumentation and unsatisfactory precision. The narrow-bore core-shell RP-C18 column was served as the front tool to accomplish efficient chemo-selective separation within those coumarins bearing similar chemical structures, a dilution pump was introduced between the two columns to facilitate the optimization of optimum elution program from the chiral column, and a wide-bore chiral column offered the enantio-separation potential for those enantiomers. Predictive MRM mode was deployed to sensitively detect the chemical components, and the enhanced product ion program was utilized to acquire MS2 spectra for all signals. Structure confirmation was conducted by matching the fragment ion species with the well-proposed fragmentation rules. As a result, 61 components, in total, were found from Peucedani Radix, including eleven pairs of enantiomers. Above all, achiral-chiral LC-predictive MRM is a promising tool for the quantitative and qualitative analysis of the complicated matrices, beyond herbal medicines, which are featured by enantiomerically enriched mixtures.