INVESTIGATION INTO THE DETECTION OF NITRATED ORGANIC-COMPOUNDS AND EXPLOSIVES BY DIRECT CHEMILUMINESCENT EMISSION DURING THERMALLY-INDUCED GAS-PHASE DECOMPOSITION REACTIONS

The selective detection of explosive compounds by gas phase chemilumin esence is investigated. When the vapour from a range of explosive comp ounds was heated, including nitrate esters and nitramines, a blue-gree n chemiluminescent emission was observed during the decomposition proc ess. This phenomenon occurred at sub atmospheric pressures, after pure vapour was admitted into a heated and evacuated reaction vessel. Howe ver, the emission intensity was increased when helium or nitrogen gas was used to assist the transport of the vapour into the reaction vesse l. Limits of detection under static reaction conditions were obtained for a number of compounds, for example, 0.013 Pa isopropyl nitrate in 1.3 x 10(4) Pa helium. The chemiluminescent reaction of a number of ex plosive compounds was examined in a flow reactor, Samples could be dir ectly injected, or admitted after gas chromatographic separation. It w as observed that the simple alkyl nitrates (e.g., ethyl nitrate and pr opyl nitrate) were more stable than cyclotrimethylene trinitramine (RD X) and pentaerythritol tetranitrate (PETN), and thus gave a lower limi t of detection. This method offers the potential for enhanced selectiv ity over current detection methods for explosive compounds of forensic interest.