Ambient ionization mass spectrometry for rapid screening of illegal adulteration in traditional Chinese medicines: a review

Illegal adulteration of traditional Chinese medicines has become a critical global safety concern, driven by the covert addition of synthetic pharmaceuticals such as phosphodiesterase type five inhibitors, anorectic agents, nonsteroidal anti-inflammatory drugs, corticosteroids, and sedatives. This review critically examines the rapid expansion of ambient ionization mass spectrometry technologies and evaluates their performance in detecting diverse adulterants across powders, pills, decoctions, creams, and botanical tissues. Techniques including desorption electrospray ionization, direct analysis in real time, wooden tip electrospray ionization, paper spray ionization, thermal desorption electrospray ionization, low temperature plasma ionization, and dielectric barrier discharge ionization demonstrate high sensitivity, structural specificity through tandem mass spectrometry, and near zero sample preparation, enabling analysis within seconds. Evidence from the past decade shows strong concordance between ambient ionization mass spectrometry screening and laboratory based chromatographic confirmation, highlighting its transformative role in high throughput surveillance, border inspection, and emergency toxicology diagnostics. The review further analyzes limitations related to matrix effects, quantitative variability, identification of novel analogues, and challenges in regulatory acceptance. Overall, ambient ionization mass spectrometry represents a significant advance for rapid front line detection of pharmaceutically adulterated herbal products, offering a scalable and versatile platform that strengthens public health protection.