Rapid detection of adulterated drugs in herbal dietary supplements by wooden-tip electrospray ionization mass spectrometry

Adulteration of herbal dietary supplements with unlabelled drugs is illegal and can lead to serious health problems in consumers. In this study, wooden-tip electrospray ionization mass spectrometry (WT-ESI-MS) was developed for rapid detection of adulterated drugs in three categories of herbal dietary supplements, namely tranquilizer, aphrodisiac and weight-loss products. Samples were directly taken by using pre-wetted wooden tips and analyzed by WT-ESI-MS, with the drug identities confirmed by MS/MS spectra. Furthermore, a high-throughput WT-ESI-MS method was developed to allow automated WT-ESI-MS and MS/MS analysis of herbal dietary supplement samples with an analysis speed of similar to 15 seconds per sample. The limits of detection of typical drugs were found to be at the ng g(-1) level using the WT-ESI-MS method. In this study, 33 commonly adulterated drugs were investigated and a spectral database containing the ESI-MS and ESI-MS/MS spectra of these drug standards was established. A total of 144 herbal dietary supplements were analyzed and the results were compared with those obtained by using high performance liquid chromatography. These results demonstrated a simple and comprehensive approach for rapid detection of adulterated drugs in herbal dietary supplements.