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Aerosol Spray to Identify Bombing Suspects
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."
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
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.
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.