Analysis of Ammonium Nitrate/Urea Nitrate with Crown Ethers and Sugars as Modifiers by Electrospray Ionization-Mass Spectrometry and Ion Mobility Spectrometry

Ammonium nitrate (AN) and urea nitrate (UN) are commonly used materials in improvised explosive devices (IEDs). Detection by mass spectrometry (MS) and/or ion mobility spectrometry (IMS) is traditionally difficult. The major challenges of detecting these species arise from their ionic nature and their low mass (for MS detection) and size (for IMS detection). Although AN and UN both produce characteristic higher mass (and size) cluster ions when ionized by electrospray ionization (ESI), detection of AN/UN using cluster ions poses difficulty at trace levels because their formation is concentration-dependent. The addition of modifiers to the ESI process is demonstrated here to overcome some of these challenges for the detection of AN and UN using MS and/or IMS.