Atmospheric Pressure Photoionization (APPI): Ambient Analysis in the Security Industry

Jack Syage, Morpho Detection, California, USA
Andrey Vilkov, Morpho Detection, California, USA
Karl Hanold, Morpho Detection, California, USA

Ambient ionization/analysis has been used for decades in the security industry, beginning with the use of swabbing material inserted into thermal desorbers followed by ionization and ion mobility spectrometry (IMS) analysis. New generation explosives trace detectors (ETDs) are being developed improving on sample collection/delivery, ionization, and mass analysis (e.g., use of mass spectrometry).

Photoionization has gained significant recognition and acceptance for its unique benefits in the ionization and detection of a broad range of compounds and specific classes of compounds that present problems to other ionization methods. Atmospheric pressure photoionization (APPI) has specific benefits that make it well suited to the detection of a wide range of explosives compounds; particularly the troublesome nitrate compounds and explains why it is being incorporated into the latest generation of ETDs. We will review these implementations to IMS and MS instruments and discuss the ionization mechanism including use of dopants to achieve highly specific detection of a broad range of explosives and narcotics. APPI has emerged as a critical technology for explosives trace security screening with projected deployment in the many thousands.