Recent application of direct analysis in real time mass spectrometry in plant materials analysis with emphasis on traditional Chinese herbal medicine

Direct analysis in real time (DART) represents a new generation of ionization techniques that are used to rapidly ionize small molecules under ambient environments. The combination of DART with various mass spectrometry (MS) instruments allows analyzing multiple plant materials, including traditional Chinese herbal medicines (TCHMs), under simple or no sample treatment conditions. This review discussed the DART principles, including devices, ionization mechanisms, and operation parameters. Typical spectra detected by DART-MS were exhibited and discussed. Numerous applications of DART-MS in the fields of plant material and TCHM analysis were reviewed, including compound identification, biomarker discovery, fingerprinting analysis, and quantification analysis. Besides, modifications and improvements of DART-MS, such as hyphenated application with other separation methods, laser-based desorption techniques, and online sampling configuration, were summarized as well.