New bomb detector spray

Urea nitrate is a colorless crystalline substance which is similar in appearance to sugar. It is used in fertilizers — and in bomb making. Professor Joseph Almog of the Hebrew University´s Casali Institute of Applied Chemistry in Jerusalem has developed a chemical color test in which a suspect’s hands are wiped with treated cotton, which will turn bright red if the individual had recently touched urea nitrate. The test is based on the formation of a red dye in the chemical reaction between the chemical p-dimethylaminocinnamaldehyde and urea nitrate under neutral conditions. Almog and research student Nitay Lemberger have added the bomb detector test to an arsenal of other forensics tests. Almog, a former Israeli Police Brigadier General and Director of the Identification and Forensic Science Division of the Israeli Police, has done previous research on color changing test fluids. Among his inventions: Ferrotrace, a chemical which turns dark violet when sprayed on hands that have recently held a pistol or grenade; an agent which reveals hidden fingerprints; and a kit that can identify a wide variety of explosives.

There are other methods to detect urea nitrate, but the spray is much simpler and less expensive and thus is likely to be used more widely. Another advantage is that the spray can detect minute traces of the explosive not only on hands, but also on door handles, luggage containers, and vehicles. The chemical can also distinguish with a high level of accuracy between sugar or other similar white powders and urea nitrate.

-read more in Nitay Lemberger and Joseph Almog, “Structure Elucidation of Dyes That Are Formed in the Colorimetric Detection of the Improvised Explosive Urea Nitrate,” Journal of Forensic Science 52, no. 5 (September 2007) (doi:10.1111/j.1556-4029.2007.00504.x): 1107-10