Rapid analysis of controlled substances using desorption electrospray ionization mass spectrometry

The recently developed technique of desorption electrospray ionization (DESI) has been applied to the rapid analysis of controlled substances. Experiments have been performed using a commercial ThermoFinnigan LCQ Advantage MAX ion-trap mass spectrometer with limited modifications. Results from the ambient sampling of licit and illicit tablets demonstrate the ability of the DESI technique to detect the main active ingredient(s) or controlled substance(s), even in the presence of other higher-concentration components. Full-scan mass spectrometry data provide preliminary identification by molecular weight determination, while rapid analysis using the tandem mass spectrometry (MS/MS) mode provides fragmentation data which, when compared to the laboratory-generated ESI-MS/MS spectral library, provide structural information and final identification of the active ingredient(s). The consecutive analysis of tablets containing different active components indicates there is no cross-contamination or interference from tablet to tablet, demonstrating the reliability of the DESI technique for rapid sampling (one tablet/min or better). Active ingredients have been detected for tablets in which the active component represents less than 1% of the total tablet weight, demonstrating the sensitivity of the technique. The real-time sampling of cannabis plant material is also presented.