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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."

24 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 reverseengineer · · Score: 3, Informative
      Well, according this earlier abstract by the same group (the paper from two years ago where they originally propose the dye- the paper linked to the article is really just about using X-ray crystallography to study the structure of the dye/urea nitrate complex):

      Urea itself, which is the starting material for urea nitrate, does not react with p-DMAC under the same conditions. Other potential sources of false positive response e.g., common fertilizers, medications containing the urea moiety and various amines, do not produce the red pigment with p-DMAC. Exhibits collected from 10 terrorist cases have been tested with p-DMAC. The results were in full agreement with those obtained by instrumental techniques including GC/MS, XRD and IR.

      From what I know of the chemistry of aldehydes (there's a great icebreaker at parties...), this dye should react with any primary or secondary amine- like regular old urea, ammonia, amino acids, etc. What this group claims, however, is that there is a particular color change reaction for this dye which occurs for urea nitrate which does not occur for other amines.

      I think what the article's confusing picture of the dye and urea nitrate interacting is suggesting is that the hydrogen bonds between the nitrate and urea moieties remain intact even after the urea has bonded to the dye, so the nitrate moiety affects the dye complex and the color it appears. I'd still be concerned about false positives, personally, particularly from different amine salts. The color produced might be uniquely identifiable to a spectrophotometer, but for a visual test I'd be worried about anything that turns "reddish" enough to produce a false positive.

      --
      "FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
    6. 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.

    7. Re:Basic hygiene by rve · · Score: 3, Interesting

      The Birmingham six were convicted largely based on the result of such a test.

      http://en.wikipedia.org/wiki/Birmingham_Six/

      Indicator tests are nothing new by the way, and they're not inherently useless, as long as you realize that they tend to be non-specific, and usually react with a whole range of compounds. If you have a sample that you know may contain either substance A or B, and you know only substance B reacts with your color spray, then the reagent is a quick and reliable way to tell the difference.

      If on the other hand you start spraying it on people who may have been in contact with any number of substances, and then accuse anyone with a positive reaction of terrorism, innocent people are going to end up in jail.

    8. Re:Basic hygiene by kcelery · · Score: 3, Informative

      and catch a lot of farmers.

  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. First silly string, now spray paint? by damn_registrars · · Score: 3, Funny

    I recall that troops in Iraq had already started using silly string to detect IED's. Now we're going to spray paint people to try to find who made the bombs? I'm waiting to see what 7-11 product shows up on the battlefeild next...

    --
    Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
    1. 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.
  5. 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.
  6. Hopefully, it is not a by davidsyes · · Score: 3, Funny

    piss-poor detector...

    (captcha: enrage)

    --
    Previously: "Linux... Toward the Sunrise..." Now: "Linux... Toward the-- No, now, part of Every Sunrise"
  7. 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.

  8. 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.

  9. I am against this... by feepness · · Score: 5, Funny

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

  10. 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
  11. 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.

  12. marking spin by drDugan · · Score: 3, Insightful

    someone got the marketing spin engine revving to 50K RPM today:

    "that can identify people suspected of making or planting bombs."

    Bullshit. Using the spray may detect a chemical, (not people) which then people may use to suspect one another.
    Big difference.

  13. Re:ever since oklahoma city anyway by the+Jim+Bloke · · Score: 3, Informative

    Quote "When was the last time anyone heard about an ANFO bomb going off somewhere anyway?" Depending on the minesite, from once a week to twice a day. Ammonium Nitrate(urea) and Fuel Oil explosives are the backbone of the industrial explosives. There are legitimate uses for explosives, and legitimate uses for ammonium nitrate. A chemical sensor that detects firearm propellants would be more useful for finding criminals - except we are talking about the USA and its miltiary adventures anyway. Just because I work around explosives, and have a beard, does not make me a bomb hurling radical.

    --
    Big Brother watching us has got to be better than us having to watch Big Brother