Ultrafast Gas Chromatography-Tandem Differential Mobility Spectrometry: Toward A New Generation of On-Site, Real-Time Trace-Explosives Detection.

In the defense and security sector, rapid detection of trace quantities of threat materials is paramount. Traditional instrumentation typically relies on standalone ion mobility techniques due to being inexpensive, portable, and highly sensitive. However, these techniques face limitations when handling complex samples, suffering from low resolving power (often less than 100) and ion-suppression effects, which can lead to false-positive and false-negative results. Here, we present a foundation to the solution through the hyphenation of the flow field thermal gradient gas chromatograph (FF-TG-GC) developed by HyperChrom with a tandem differential ion mobility spectrometer (DMS-DMS) developed in-house at New Mexico State University. The FF-TG-GC demonstrates the ability to separate a variety of nitroaromatic compounds of explosive significance in 20 s using a nitrogen carrier gas, highlighting the potential to offer selectivity advantages without substantially compromising high-throughput demands. These selectivity advantages are illustrated by the successful application of the FF-TG-GC-DMS-DMS to the detection and identification of single-nanogram loadings of 18 explosives and related substances in the presence of interfering materials, such as lactic acid, musk, and diesel. Furthermore, the system is capable of mitigating in-source ion-suppression effects by chromatographic separation of target analytes from background interference prior to ionization.