The Effect of Humidity and Dopants on the Detection of TNT Vapor by Differential Ion Mobility Spectrometry (DMS)

The aim of this study was to investigate the effect of an external factor, i.e. humidity, on the detectability of TNT vapor by Differential Ion Mobility Spectrometry (DMS). The values of TNT signal amplitude and asymmetric voltage were measured as a function of relative air humidity. The influence of the use of a semi-permeable membrane and the additive agent - dopant (nicotine and dichloromethane) on the detection under varying air humidity conditions was also investigated. The analysis of the obtained results confirms that the introduction of dopant to the analyzed stream contributes to the change of TNT detection parameters. The DMS detector allows you to observe the signal in two polarizations (positive and negative), which is an advantage compared to the competitive FAIMS method. It was observed that water vapor content above 30% causes the formation of two analytical signals for TNT. This, in turn, may improve the identification process. The addition of nicotine and dichloromethane reduces the amplitude of the air signal, which has a beneficial effect on TNT detection.