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A field diagnostic test for the improvised explosive urea nitrate.
Joseph Almog1, Asne Klein, Tsippy Tamiri
1Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. Almog@vms.huji.ac.il
Journal of Forensic Sciences
|June 4, 2005
Summary
A new color test accurately detects urea nitrate, an improvised explosive. This simple method uses p-dimethylaminocinnamaldehyde (p-DMAC) to produce a red color, distinguishing it from urea and other substances.
Area of Science:
- Forensic Chemistry
- Analytical Chemistry
- Explosives Detection
Background:
- Urea nitrate is a common improvised explosive.
- Rapid and reliable detection methods are crucial for security.
- Existing detection methods can be complex or require specialized equipment.
Purpose of the Study:
- To develop a simple, sensitive, and specific colorimetric test for urea nitrate.
- To differentiate urea nitrate from its precursor, urea.
- To validate the test against real-world samples.
Main Methods:
- A colorimetric reaction utilizing p-dimethylaminocinnamaldehyde (p-DMAC).
- Testing under neutral conditions to optimize specificity.
- Analysis of various potential interferents including fertilizers, medications, and amines.
- Validation using samples from 10 terrorist cases.
Main Results:
- The reaction between urea nitrate and p-DMAC produces a distinct red pigment.
- Urea, fertilizers, medications, and amines did not yield a positive result.
- The p-DMAC test results perfectly matched instrumental analyses (GC/MS, XRD, IR) on case exhibits.
Conclusions:
- The p-DMAC color test is a highly sensitive and specific method for detecting urea nitrate.
- This simple test offers a reliable alternative to instrumental techniques for field identification.
- The test's specificity minimizes false positives, enhancing its practical utility in forensic investigations.