Rapid detection of explosive vapors by thermal desorption atmospheric pressure photoionization differential mobility analysis tandem mass spectrometry

Rationale The increased frequency in the number of international terror threats has led to a corresponding increase in demand for fast, sensitive and reliable screening methods suitable for the detection of airborne explosive vapors. We demonstrate herein a workflow suitable for the determination of nitrogen-based explosives at the picogram level in just minutes. Methods A method is described that combines Thermal Desorption (TD) sample introduction with Differential Mobility Analysis (DMA) Tandem Mass Spectrometry (MS/MS), enabling a sensitive and accurate workflow suitable for the rapid detection of trace nitroaromatic, nitroester and nitramine explosive vapors. The methods are bridged using a novel low-flow, field-free Atmospheric Pressure Photoionization (APPI) source, intended specifically for the analysis of gas-phase analytes and airborne particles. Results Limits of detection within or below the picogram range were determined for the analysis of a range of explosives standards including 2,6-DNT, TNT, TATB, Tetryl, RDX, EGDN, PETN, HMX, and NG. Practical application of the TD-APPI-DMA-MS/MS workflow was demonstrated for the detection of real trace explosive vapors produced from the volatilization of solid explosive samples stored within a sealed cardboard box. A single complete analysis was performed in less than 2 min. Conclusions The highly sensitive and accurate detection of a variety of common nitrogen-based explosive vapors has been demonstrated, at levels suitable for practical, high-throughput security screening applications.