Online Monitoring of the Processing of Traditional Chinese Medicine by Neutral Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

The pharmacological effects of traditional Chinese medicine (TCM) are closely associated with the processing procedures, which involve a multitude of intricate chemical reactions. Real-time monitoring of the dynamic changes in chemical constituents during TCM processing plays a pivotal role in ensuring quality control of TCM products. Herein, a neutral desorption atmospheric pressure chemical ionization mass spectrometry (ND-APCI-MS) method was developed for online monitoring of the TCM processing. The aerosol generated during the TCM processing was sampled in situ by neutral desorption using N2, followed by online analysis using APCI-MS. Subsequently, orthogonal partial least squares discriminant analysis (OPLS-DA) was employed to analyze the MS data to find the biomarkers associated with the processing. Compared to traditional tissue-based analytical methods, the present method employing aerosols as samples takes advantage of online analysis, nondestructive sampling, and enhanced accuracy. As a conceptual application, the processing of Rehmannia glutinosa was investigated, and several biomarkers associated with the processing were identified. These findings suggest the potential application of ND-APCI-MS for online and in situ monitoring of the processing of TCM.