Accurate detection of trace level black powder with miniaturized Fourier deconvolution ion mobility spectrometer

Black powder (BP), a low-explosive mixture, is created by mixing sulfur, potassium nitrate, and charcoal, poses significant risks due to its flammability and potential use in illicit activities. Accurate detection of black powder (BP) is crucial for public safety, security, and regulatory compliance. However, the detection of BP is challenging when using miniaturized ion mobility spectrometers because of the sulfur ion peak overlaps heavily with that of the reactant ions ($O_2^{-}{\left(H_{2}O\right)}_n$). A simple method is proposed in this study for accurate and sensitive detection of BP, utilizing a miniaturized Fourier deconvolution ion mobility spectrometer (FD-IMS), which directly improves the resolution between the $O_2^{-}{\left(H_{2}O\right)}_n$ peak and the sulfur ion peak without the need to add any chlorinated hydrocarbon modifiers, and avoids the complexities and contamination risks posed by modifiers in the conventional method. The demonstrated device achieved a resolution of up to 2.07 between the $O_2^{-}{\left(H_{2}O\right)}_n$ and $S_3^{-}$ ion peaks at a drift region voltage and length of 1.54 kV and 42.5 mm, under optimized detection temperature and drift gas humidity, with a minimum detectable quality of sulfur of less than 0.1 ng. It was proven that this miniaturized FD-IMS is qualified to detect trace level BP less than 1 ng as well as other nitro-organic explosives.