Performance Abstract on the EST-4200 Ultimate Vapor Tracer Page 3

Profiling of Cargo Container Odors

 

Odors from Explosives

 

Because the EST-4200 sensor is non-specific it is able to detect and quantify the vapor concentration of virtually any explosive independent of its chemical make-up e.g. nitro or non-nitro).  The probability of detecting explosives from fugitive emissions (vapor phase) within a cargo container is strongly dependent upon the temperature of the cargo container, the vapor pressure of the explosive chemicals, and how they are packaged.  For this reason explosives such as Semtex and C4, which contain high molecular weight chemical explosives like PETN and RDX are rarely detectable by vapor phase measurements.  Because of this, by international accord, all manufacturers of ‘plastic’ explosives now include a volatile taggant compound such as DMNB or MNT.  This enables vapor detection systems and canines to detect these explosives.  As an example, the complete chemical odor profile, olfactory image, and virtual sensor array response of un-packaged C4 is shown in Figure 7.  The RDX response (peak 7) is difficult to see however is is much easier to detect the volatile taggant (peak 1).

 

Not all explosives contain a nitrogen base and because of this they cannot be detected with conventional explosive trace detectors.  One explosive of this type is triacetone triperoxide (TATP) which has the explosive power of RDX yet contains no nitrogen.   This compound was used by the shoe-bomber Richard Reid and is also commonly used by human bombers in Israel.  The chemical odor profile of TATP crystals is quite simple as shown in Figure 7.  Like NG, DNT and TNT,  TATP is very volatile and fugitive emission can easily be detected in cargo containers.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

         F igure 7- Chemical odor profile of C4 explosive.                       

                                    

                                                                                                                

                                                                                                                    Figure 8- Chemical odor profile of TATP

Odors From Contraband Drugs

 

Some contraband drugs like methamphetamine and marijuana produce odiferous compounds such as THC and cannabinol which is detectable in the vapor phase by canines and the SAW based chemical profiling system.  Others such as cocaine and heroin are much more difficult because their vapor pressure is extremely low.  A virtual sensor array (Figure 9)  is used to screen a container chemical odor profile for target compounds.  The virtual sensors can be created using odors from samples of the target drugs  or by selecting the specific compounds from the system’s chemical library.

 

 The chemical odor signature of cocaine in a cargo container (Figure 10) was tested using packaged 1-kilogram bundles.  Cocaine produced little or no signal at ambient temperatures and significant vapor  concentrations could only be detected when the temperature of the container was above 50 degrees C. The presence of low vapor pressure drugs like cocaine and heroine is best done by targeting the more volatile compounds associated with the drugs.  For cocaine a natural by-product is methyl benzoate, commonly referred to as doggy-cocaine because it is used to train canines to detect this drug.  The presence of methyl benzoate is clearly visible in the room temperature odor profile shown .

 

 

 

 

 

 

 

 

 

                   Figure 9- Virtual chemical sensor array for

                        methamphetamine and marijuana.

 

                                                                                                               Figure 10- Cargo container loaded                    

                                                                                                              with 1 kilogram packages of cocaine 

 

                                                                                                                                                            

 

 

 

 

 

 

 

 

 

 

                                                                                                              Figure 12- Volatile compounds in

                                                                                                              cargo container at room temperature

            

                Figure 11- To detect cocaine vapors  in a cargo                  

                 container long sample preconcentration times                  .

                    and elevated temperatures must be used.                                                 Next Page >>>

 

 

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