Construction and Evaluation of a Fluorescent Sensor for the Detection of High Explosives

A sensor for the detection of airborne nitrate explosives was developed and laboratory tested. The device consisted of a quartz optical fiber, of which a 4-cm length was stripped and treated with an aminoalkylmethoxysilane. A fluorescent surface was produced by chemically attaching a sulfonated polyaromatic fluorophore to the amino group of the silylated quartz. Excitation was effected by radiation admitted through the fiber. When explosive laden air was drawn across the fluorescent surface, the analyte molecules interacted with the fluorophore and caused the emission to be quenched. This signal was monitored as an indicator of the explosive and was shown to be effective for TNT, di- and mononitrotoluenes, Tetryl, RDX, and HMX (marginal). Sensitivities were in the ng/m3range, and the surface could be flushed and restored after a quenching episode. Few interferences were encountered among common substances brought in contact with the surface.