Multidimensional detection of nitroorganic explosives by gas chromatography-pyrolysis-ultraviolet detection.

We describe a new methodology for the trace detection of organic explosives containing nitro functionalities. Conventional gas chromatography separates the components of an explosive mixture. Effluent from the gas chromatograph is pyrolyzed by passage over a heated Nichrome wire. Nitric oxide produced on pyrolysis of a nitroorganic compound is then detected by ultraviolet absorption spectroscopy between 180 and 240 nm, using a deuterium lamp as the light source. Nitric oxide exhibits a sharply banded, characteristic spectrum in this region, enabling detection of nitroorganics. The system is tested using the explosive simulants nitrobenzene and 2,4-dinitrotoluene, and with the nitramine explosive tetryl. Detection limits are 25 ng for nitrobenzene and 50 ng for 2,4-dinitrotoluene. Tetryl is detected with a detection limit of 50 ng. The system is both easy to implement and could be built as a compact, low-power device.