Direct detection of explosives on solid surfaces by low temperature plasma desorption mass spectrometry

TLDR

A transient, low‑temperature non‑equilibrium plasma of ions, electrons, and metastable atoms is generated between the electrodes during discharge. The study constructs a low‑temperature plasma probe using dielectric barrier discharge and applies it to detect explosives on various substrates under ambient conditions. The probe directly desorbs and ionizes TNT, RDX, and PETN from solid surfaces, with the resulting ions analyzed in negative‑ion mode by mass spectrometry. The technique achieves limits of detection of 500 fg for TNT, 1 pg for RDX, and 500 fg for PETN, successfully analyzes a mixture of the three explosives, and detects trace explosives on both conductive and non‑conductive substrates.

Abstract

In this paper, we have constructed a low temperature plasma (LTP) probe using dielectric barrier discharge (DBD) and employed it for the detection of explosives on a variety of substrates under ambient conditions. Upon discharge, a transient, low-temperature non-equilibrium plasma comprising ions, electrons and metastable atoms are generated between the electrodes. Three common explosives, 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-trinitro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN), were directly desorbed and ionized from solid surfaces, followed by subsequent analysis using the mass spectrometer in the negative ion mode. Limits of detection (LODs) were 500 fg for TNT, 1 pg for RDX, and 500 fg for PETN. The reliability of the method was characterized by a successful analysis of a mixture of the three explosives. The ion source also allowed direct detection of trace explosives on both conductive and non-conductive substrates, thus expanding the applicability of low temperature plasma desorption mass spectrometry.