Explosive Trace Detector (ETD) technology well-suited to identify explosives of small magnitude. The detection is performed by sampling invisible trace amounts of particulates.
The Explosive Trace Detection methodology is based on NanoTechnology as it shows the positive result on explosive material of nanograms or less i.e
1 ng= 10^9 or one-billionth of one gram. The most relevant method to handle the diminutive quantity of explosive material is to diffuse them in an organic solvent. Further to nanomaterial other techniques which show their utility which is detecting are the optical, electrochemical, biological and thermal sensor.
It plays a prominent role in maintaining national security like in airports and other vulnerable zones which are susceptible to any illegal or unethical interference, which is an analytical technique for operational uses. Because of its low cost, easy portability and sensitivity effectively used for screening purposes to check the baggage or luggage in airports, railway stations.
It produces an alarm when it identifies any explosive although it did not detect any bomb it signifies the presence of vapour in the particles which only found in the particulates of explosive material. The technique is used to detect the type of materials but may and may not be identified as the quantity of the explosive.
Working Principle of Explosive Trace Detector-
As an Explosive Trace Detector based on nanoparticles which are then dissolved in organic material. Such explosives can be retrieved from the solution as a volatile solvent will evaporate very rapidly at room temperature and the explosive material will be left in the sampling pad.
Sample collection– Sampling process can be of two type- swipe collection method or vapour collection method. A swipe methodology sample is collected from the surface as a residue and put in the sample port which is the instrument to detect. While in the vapour technique, it collects vapour present in the atmosphere or baggage or container. Then it collected in a sampling port and followed the same procedure as followed in the swipe method.
Detection Method– the procedure explosive trace detector follows from collecting to dissolving onto a sampling is as follow-
- The system is turned on and checks the volume of the alarm.
- With the use of syringe collect and place the sample of explosive in a volatile solvent solution inside the sampling pad.
- Wait for a bit for the solvent to evaporate.
- Observe the system resonance and record whether it is alarming or not.
- Record the sampling details after alarming occurs if alarming not take palace repeat thrice the procedure for better result.
- Then once the system is set i.e generating an alarm, test the mass amount of explosive for this mass is 90% or greater, if less than 90 per cent double the mass and reperform.
- Perform the series of testing with ten different masses and determining the system is ranging or not.
The total processing time is equal to the sum of sampling time and analysis time.
Technologies used for Chemical analysis-
Colorimetric technique is one of the simplest and oldest methods to identify by a color reaction which is known as an indicator which detects the explosive material.
Ion mobility spectrometry based on the principles of separation of electronegative molecules where lower mass molecules move faster than heavier molecules and thus detect by the negative ion current collection.
Chemiluminescence is based on the luminescence of certain compounds (nitrogen contains compounds) when they attach to explosive particles and are detected by measuring the light emitted from the excited states. They are mostly used in non- electronic types of equipment such as spray and test papers etc.
Atmospheric pressure Electron Ionization in this technique molecules is charged selectively for the molecular analysis by ion mobility spectrometry.
Mass spectrometry is an emerging technology because of its accuracy probability ratio and its miniature size. It produces a lower false rate because of high resolution, based on non-radioactive ionization methods.
Explosive Trace Detection (ETD) technology has its immense scope in the present automation world where everything is roundup in nano. To strive and strengthen the surveillance system along with assuring the security of the people from antisocial activities it is a very essential tool.