A Tandem Mobility Spectrometer for Chemical Agent and Toxic Industrial Chemical Monitoring

Abstract

Sensitivity, selectivity, and speed are the most important analytical parameters in sensing chemical warfare agents (CWAs) and toxic industrial chemicals (TICs). For homeland security applications, where protection from chemical releases in public facilities such as at airports or subway stations is desired, selectivity becomes even more critical since false alarms can cause costly societal disruptions and trigger public panic. Currently, ion mobility spectrometry (IMS) has been widely deployed in the battlefield for CWA detection because of its excellent sensitivity and speed. However, IMS alone has suffered from low selectivity, especially for lower molecular weight TICs, which results in false alarms. This article describes an emerging technology that combines differential mobility spectrometry (DMS) and IMS in one package. In this configuration, the DMS serves as an ion filter for the IMS, prescreening targets from background with a separation mechanism that is complementary to the IMS. The tandem analyzer consists of a microfabricated DMS and two miniaturized IMS detectors arranged in an orthogonal configuration, enabling the detection of positive and negative ions simultaneously. The combination of these two technologies can significantly reduce false alarm rates. The tandem DMS–IMS provides a real‐time, powerful technology to counter terrorist threats in infrastructure protection scenarios.