Detection of explosives by plasma optical emission spectroscopy

A new pre-concentration/separation system coupled to a micro-hollow glow discharge (MHGD) plasma detector is demonstrated for the analysis of explosives. The detector and spectrometer are miniaturized and field-portable. Separation eliminated air interferences while pre-concentration improved detection limits for TATP (triacetone triperoxide) and DNT (dinitrotoluene). In the analysis step, a temperature ramp desorbed the two explosives into an entraining Ar flow. Optical emission spectroscopy (OES) was applied to detect the plasma generated atomic and diatomic radicals using a spectrometer at atmospheric pressure. For both test species, the detection limits reached values lower than 5 ppb. The effect of an at-sea environment was also evaluated. Such a detector system is very promising for the detection of explosives due its small size, high sensitivity and selectivity.