Polymeric Reagents for the Detection of Urea Nitrate

Yoav Barkan, School of Pharmacy-Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
Konda Reddy Kunduru, School Of Pharmacy-faculty Of Medicine, The Hebrew University Of Jerusalem, Jerusalem, Israel
Arijit Basu, School Of Pharmacy-faculty Of Medicine, The Hebrew University Of Jerusalem, Jerusalem, Israel
Abraham Domb, School Of Pharmacy-faculty Of Medicine, The Hebrew University Of Jerusalem, Jerusalem, Israel

Onsite rapid, sensitive, and accurate detection of urea nitrate (UN) is an important global security challenge. UN can be easily obtained from the reaction of urea and nitric acid. UN is a stable crystalline chemical compound insensitive to electrostatic discharge, mechanical shock, or friction. It is extremely difficult to visually distinguish, and easily disguised as sugar. Almog et al. developed a color test for the detection of UN based on the formation of a red dye between p-dimethylaminocinnamaldehyde (p-DMAC) and UN under neutralconditions [1]. The resultant enhanced resonance of p-DMAC-Urea complex is responsible for the color development. The nitrate ion in UN can be detected by the Griess reagent composed of N-(1-naphthyl)ethylenediamine and sulfanilamide in the presence of zinc an reducing agent [2].

This report describes the synthesis and characterization of polymers and hydrogels containing the Almog and Griess reagents for the detection of UN. Polymers with Griess reagent side groups and hydrogel film loaded with both the Almog and Griess reagents have been synthesized and tested for UN detection. Color change, from light yellow to purple-red, was visualized when exposed to 2-10 ppm of UN vapors or solution. These polymers have a potential use for field detection of ppm levels of UN.

[1] J. Almog, A. Klein, T. Tamiri, Y. Shloosh, S. Abramovich-Bar, A field diagnostic test for the improvised explosive urea nitrate, J. Forensic Sci. 50 (2005) 582–586. 

[2] Griess, P., Bemerkungen zu der abhandlung der H.H. Weselsky und Benedikt "Ueber einige azoverbindungen". Chem. Ber., 12, 426 (1879), in German.