Slashdot Mirror

← Back to Stories (view on slashdot.org)

Aerosol Spray to Identify Bombing Suspects

Posted by samzenpus on from the spray-the-terror-away dept.

RedHanded writes "Forensic chemists at the Hebrew University of Jerusalem have developed a color-changing spray that can identify people suspected of making or planting bombs. The chemical turns from yellow to bright red when it comes into contact with urea nitrate, an explosive residue that may be left behind on the hands of someone who has handled an improvised device."

17 of 191 comments (clear)

  1. Basic hygiene by LiquidCoooled · · Score: 5, Insightful

    How many false alarms are they going to get after people don't wash their hands after visiting the bathroom?

    Maybe that is what they are looking for - poor hygiene = terrorist?

    Perhaps this chemical is the same one which makes the purple cloud of shame in the swimming pool (I know its a legend but still..)

    --
    liqbase :: faster than paper
    1. Re:Basic hygiene by Anonymous Coward · · Score: 4, Funny

      From the article:

      Spraying this substance in the air will show the farts of anyone in the room as a blue haze.

      Ha ! Finally some way to track down the lactose intolerant!

    2. Re:Basic hygiene by Upaut · · Score: 5, Interesting

      Only if this person with bad hygiene sweats nitric acid...

      I'm more worried about, well, me... I use urea nitrate in my tropical orchid mix...

      --
      3 degrees of separation from Vladimir Putin
    3. Re:Basic hygiene by fbjon · · Score: 4, Funny

      I was thinking more like: yellow is neutral, red is enemy. So, air-burst a big bomb with this, take satellite pics, and you have an instant minimap!

      --
      True confidence comes not from realising you are as good as your peers, but that your peers are as bad as you are.
    4. Re:Basic hygiene by battery111 · · Score: 5, Interesting

      Well, not exactly. I don't know enough about how the chemical works (it will likely be found to cause cancer in the state of california at a later date), but part of manufacturing urea nitrate is indeed to distill ones urine. My guess is that it would have to be at a relatively high concentration in order to react, but that may not be the case, which would cause a large number of false positives. Another thing to keep in mind is that urea nitrate is only one of a large number of homemade explosives, and not really the most common, so while it is a promising advance, it really is not the be all end all of bombmaker detection. One also has to raise questions about its effects on personal privacy, but likely in the areas this is going to be employed, it may be a secondary consideration.

    5. Re:Basic hygiene by Rutulian · · Score: 4, Informative

      Unless you make it yourself, I think it is unlikely you have urea nitrate in your fertilizer. You probably have urea + potassium nitrate (or ammonium nitrate). To form urea nitrate, you need a strongly acidic conditions.

      From the article, the "amazing" new molecule is just commercially available p-dimethylaminocinnamaldehyde. The chemistry involved is already well-known. It is used for, among other things, indirectly detecting biotin (by way of the urea in the molecule). Basically you mix your urea-containing compound with a strong acid (sulfuric acid works), which promotes enol tautomerization and makes the normally unreactive nitrogens of the urea reactive toward electrophiles. One of the nitrogens will react with the aldehyde to form an imine, and due to the availability of a quinoid resonance contributor, turn color (red in the case of dimethylaminocinnamaldehyde and yellow in the case of dimethylaminobenzaldehyde).

      What's special here, and why this won't result in a thousand false positives from detection of any urea-containing compound, is that urea nitrate is a stable salt and acidic enough on its own to react with dimethylaminocinnamaldehyde without the addition of acid. So a wipe test, drop it in isopropanol, add some of the aldehyde and see if it changes color. It's a fairly elegant application of old chemistry to forensic analysis.

  2. bomb makers or... by Jherico · · Score: 4, Insightful

    Bomb makers or maybe farmers who handle fertilizer? I don't envy being a false positive in Iraq.

    --

    Jherico

    What can the average user can do to ensure his security? "Nothing, you're screwed"

    1. Re:bomb makers or... by Osty · · Score: 4, Funny

      Washing them when you go is disgusting.

      No it's not. It's multi-tasking!

  3. It's a good thing... by Anonymous Coward · · Score: 4, Insightful

    It's a good thing that terrorists never wash their hands.

  4. Congratulation! by Daimanta · · Score: 5, Insightful

    Terrorists will now use gloves to make bombs. Innocent people will be falsely identified as being a terrorist.

    Mission accomplished!

    --
    Knowledge is power. Knowledge shared is power lost.
  5. That is why... by j.+andrew+rogers · · Score: 4, Insightful

    ...smart terrorists only use peroxide-based explosives (like the London subway bombing et al), oxidized halide based explosives (e.g. chlorate), and various other dirt cheap and ubiquitous explosives. While many of the most famous explosive chemistries might be subject to nitrate tests, the range of explosive chemistries that have been used at various times is far more diverse than nitrates. First World War mortar explosives are as dangerous today as they were back then, even if some of them do not contain nitrates.

    The fixation on the detection of nitrate and related chemistry is a bit of a blind spot in explosive detection technology.

  6. More Griess Test Nonsense by Anonymous Coward · · Score: 5, Informative

    In the UK, the Birmingham Six were falsely imprisoned for 16 years (one chap died in prison) largely because of the Griess test. The trouble is, anything nitrated will give a positive. The playing cards the men had been using on the train when they were arrested were probably what set it off. Ping pong balls certainly would. Imagine Forrest Gump in the Twenty First Century, "And then I met the President again, then they tasered me, then I went to prison for life." The Griess test is now completely discredited. Its re-introduction would be on a par with admitting polygraphs, or examining chickens' giblets as evidence, whether it's packaged as an aerosol or anything else.

  7. Re:First silly string, now spray paint? by pintpusher · · Score: 5, Informative

    I believe it is used to detect tripwires. Silly string sprayed ahead of you will drape over tripwires without being heavy enough to trip them. makes sense to me anyway.

    --
    man, I feel like mold.
  8. I am against this... by feepness · · Score: 5, Funny

    I think labeling people as terrorists because of their color is just wrong.

  9. Alternative use: Detecting IEDs themselves. by Ungrounded+Lightning · · Score: 4, Insightful

    I recall that troops in Iraq had already started using silly string to detect IED's.

    I wonder if a light spray of this stuff would make a hidden IED stand out as a bright red spot?

    And perhaps with red trails marking how it arrived and where the people who delivered it went when they left?

    --
    Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
  10. You Know You've Read Slashdot Too Long... by Looshi · · Score: 5, Funny

    ...when your first thought is the effect on the rights of the bomb makers.

    1. Re:You Know You've Read Slashdot Too Long... by SMS_Design · · Score: 4, Insightful

      Sure, I'm concerned about the rights of bomb-makers. I, myself, made a few good ones when I was growing up out in the country. Mainly, though, I'm concerned about the rights of EVERY OTHER CITIZEN who will be needlessly harassed because of some bullshit test that will have 1000+ false positives for every actual bomb prevented.