TNT sensor

[gr8guy]

i am researching on making a Explosive (TNT) sensor for my sciece fair.... but i am not getting much information on it.... please help me that how can i make a simple explosive sensor whcih can detect explosives..
the last date of project is 15th october 2008 so please help me... i dont have much time.

[ChrisG]

Hi gr8guy,
Welcome to the ask an expert forum. Have you tried a web search for "explosive detector"? There are many web pages that will provide you with relevant information. If you are still having trouble finding what you need, please let us know.
Thanks,
Chris

[gr8guy]

sir thanks for your reply....
the methods on the web are of a bit higher level and would be expansive. i want one whcih is cheap, unique, and easy.

[ChrisG]

sir thanks for your reply....
the methods on the web are of a bit higher level and would be expansive. i want one whcih is cheap, unique, and easy.

You will probably need to narrow the scope of your topic so that you can find something feasible for a science fair. For example, metal detection is a relatively cheap and easy method for finding land mines. I'm not recommending that as a specific topic, but I would recommend you start thinking about topics that are similarly narrow in scope.

[barretttomlinson]

Hi,

You did not say whether you wanted to detect TNT in vapor phase or solid or liquid phases. There are a large number of ways to assay for TNT, and some of them are fairly simple. Here is a reasonably cheap assay reported for contaminated soil:

http://uko.tubitak.gov.tr/ToplantiDokum ... 119df0.pdf

You might be interested in this survey of assay methods for explosives in environmental samples:

http://el.erdc.usace.army.mil/elpubs/pdf/trel05-14.pdf

And another excellent survey article on explosive detection:

http://www2.foi.se/rapp/foir2030.pdf

Here is a paper on the analysis of TNT by ion mobility analysis.

http://journals.tubitak.gov.tr/chem/iss ... 0402-5.pdf

I think it is within the capability of an advanced high school student with some skill in electronics to build an ion mobility drift tube analyzer or spectrometer. These instruments are still frequently built by investigators rather than bought from commercial companies and are not all that complicated. You can search the US Patent Office archives for patents on them. Patents are useful because in order for a patent to be issued the inventor must teach the world how to make his invention, Access to patents is free through the US patent office website:

http://patft.uspto.gov/netacgi/nph-Pars ... rometer%22

Pay attention to the sections of each patent entitled “Background of the Invention”, “Summary of the Invention” and “preferred embodiments of the invention”. For most of your purposes you can ignore the claims section of the patent.

The third approach which you may wish to consider is electrochemical analysis techniques sometimes called voltammetry or paleography. One of the prominent characteristics of TNT is that it accepts electrons easily. This makes it easy to assay by these methods. Here are some background resources:

http://www.public.coe.edu/departments/E ... rials.html

http://faculty.kutztown.edu/betts/html/ ... mistry.htm

http://www.amelchem.com/download/items/ ... al_eng.pdf

One paper on the analysis of TNT by paleography:

http://www.springerlink.com/content/q60 ... pdf?page=1

Other approaches to this analysis include gas or liquid chromatography, particularly with nitrogen specific detectors (often based on chemiluminescence’s of NO2 from the oxidation of the nitrogen compoound), GC/MS, and a number of other techniques mentioned in surveys cited above.

Realistically, for a science fair project, I suspect the best choice would be the first technique mentioned, the colorimetric assay. The ion mobility spectrometer mentioned second would be a super impressive project if you have the skills and resources to pull it off, and would get you deeply into an area of current research.

Either way, this should be a great adventure. Have fun with it!

Best regards,

Barrett Tomlinson

[gr8guy]

sir i am reallly thankful of you for helping me!!! i would definately work upon them!!

[barretttomlinson]

My word processor has been making creative edits. In the third section of my latest post the word paleography has been substituted for the correct term polarography. Sorry about that!

[beneteau]

Hi all,

This not may be the best place but I'm looking for an TNT expert who may be able to advise please!

Over Christmas, my parents and I had travelled through Europe in my car and few days later I was taking my mother to an airport when her wheelchair got detected for traces of fuel and TNT explosives!!! Now - she's only partially disabled and her wheelchair was in my car's boot all the time and there's absolutely no connection between me, my parents, my car and explosives, millitary or terrorists (as they kept asking at the airport)! They let her go 2 hrs later with no further follow up but it's been on my mind since then and I cannot understand how TNT would get detected on her wheelchair. I did have a spare fuel can at the boot so I can see where they got the traces of fuel from, but I was told there were definitely traces of TNT explosives. I have no knowledge in this area, so is there anyone who had similar experience or has any suggestions how this can happen please?

Many thanks.

Kat

[MelissaB]

The thing they are usually detecting at the airport is nitrates--compounds which are very present in fertilizer. I was at a conference once where almost everyone at the conference was stopped at the airport because we had all been walking across the lawns, which had just been fertilized. Thankfully, it was a small airport and there were lots of us so they quickly figured out the problem--but a few people still missed their flights because of that fertilizer.

[Craig_Bridge]

The most likely explaination is that TNT did NOT get detected on her wheel chair. If it was one of the swab or cotton wipe tests, then what was detected were trace elements that are typical of what would be detected from TNT or nitro glycerin or other nitrates like fertilizer. Per chance, does she or anyone who handled the wheel chair at the airport have a heart problem and carry nitro glycerin tablets in case they have an angina attack?

By your use of the word "boot" instead of "trunk", I'll assume you are in europe where the fuel was probably diesel (fuel oil). It was probably the combination that caused the length of interrogation. Nitrate fertilizer and fuel oil mixtures produce some high yield explosives from commonly available uncontrolled sources so that combination is high on the threat list.