Air-Based Porous Array Dielectric Barrier Discharge Ionization Source for Explosive Trace Detection

A novel atmospheric pressure ionization source for explosive trace detection was proposed and validated, which balances practical application requirements with detection performance. The ionization source adopted porous array dielectric barrier discharge (DBD) technology on a printed circuit board (PCB) with air as the discharge gas. Larger-area discharge improved ion generation efficiency, with the ion current exceeding 300 nA. Countercurrent gas flow effectively removed interference of ozone and reactive nitrogen oxides generated by dielectric barrier discharge. Meanwhile, pulsed discharge was employed to further reduce interference, as well as decrease power consumption and extend the lifetime of the ionization source. Combined with a homemade miniature digital linear ion trap mass spectrometer, the performance was evaluated for various typical nitro explosives (TNT, 2,4-DNT, NG, RDX, PETN, and HMX), demonstrating good linear response over a concentration range exceeding 2 orders of magnitude. Detection results of real samples and simulated mixtures further verify the applicability of this method. This DBD structure design offers advantages including compact size, soft ionization, low detection limit (e.g., 0.0025 ng for 2,4-DNT), no need for additional reagents or consumable gases, and simple operation. This work provides a feasible ionization source design for the next generation of mass-spectrometry-based explosive trace detection technology.