后目标分析法用于盐益智仁挥发性成分的顶空-气相色谱-四级杆/飞行时间质谱分析

Post-target Analysis for the Volatile Compounds from Salty Alpinia oxyphyllae Fructus with Headspace-gas Chromatography-quadrupole/time of Flight Mass Spectrometry

后目标分析法用于中药挥发性成分分析,可对复杂基体实行快速、准确、宽范围的分析,成功解决了化合物因共洗脱、柱流失等干扰无法定性的问题.气相色谱-质谱检测的结果运用图谱检索结合保留指数和准确质量的后目标分析方法从盐益智仁挥发性成分中共鉴定出119个化合物.通过保留指数推算保留时间,结合窄质量窗口提取离子色谱图的后目标分析方法降低了背景干扰,提高选择性,有利于复杂基体中痕量成分的分析,又鉴定出3个目标化合物.此外,由串联质谱推测化合物裂解规律,辅以二级质谱中碎片离子准确质量,又鉴定出一个化合物.

Post-target analysis is a superior method for qualitative analysis： This method can make a rapid, accurate and wide-scope screening for non-target and target compounds, and it has been used widely in the metabonomics, environmental analysis and pesticide residues. With post-target method to analysis non-target compounds, retention index, accurate mass and library were applied to investigate non-target analytes and then a total of 119 compounds were identified. Within those 119 compounds, there are different kinds of compounds, such as aliphatic aldehyde, aromatic ketone, aromatic aldehyde, monoterpene and its oxide, sesquiterpenes and its oxide and so on. Eremophilene is the best peak ingredient, p-cymene, aroL madendrene, nootkatone and 3-cadinene are the main ingredients. Besides, nootkatone is the main active ingredient according to previous pharmacology research. Narrow mass window extracted ion chromatograms （nw-XlC） can decrease background noise greatly and improve the signal-to-noise rate. Hence, the trace level or co-elution compounds can be identified. With the post-target analytical method for target analytes, we calculated retention time from retention index of target compounds, and then nw-XlC （mass window 0.02 Da） was carried out. Four characteristic ions of target compounds were extracted to get extracted ion chromatograms at calculated retention time. As peaks at calculated retention time had the same chroma- tographic behavior, we identified three target compounds： nootkatol, a-cyperone and periUaldehyde. Tandem mass technol- ogy has been widely used since its introduction in the 1970s, it was used in trace analysis, chemical reaction mechanistic studies and propose the fragmentation pattern of compounds. In this paper, we got first-stage mass spectra and second-stage mass spectra data in one experiment. Moreover, we could obtain accurate mass of precursor ion and product ion from sec- ond-stage mass spectra at the same time, then we inferred the MS fragmentation pattern of compounds. This method is more simple, convenient and accurate than the traditional tandem mass spectrometry. Myrtenal was identified in this post-target way. Post-target analytical method can distinguish compounds from complex matrix samples as many as possible. This method solves the problems of co-elution and high background and can be used to investigate the medicine＇s pharmacology and toxicology mechanism.