title: Analysis of ammonium nitrate headspace by on-fiber solid phase microextraction derivatization with gas chromatography mass spectrometry.
abstract: A novel analytical method has been developed for the quantitation of trace levels of ammonia in the headspace of ammonium nitrate (AN) using derivatized solid phase microextraction (SPME) fibers with gas chromatography mass spectrometry (GC-MS). Ammonia is difficult to detect via direct injection into a GC-MS because of its low molecular weight and extreme polarity. To circumvent this issue, ammonia was derivatized directly onto a SPME fiber by the reaction of butyl chloroformate coated fibers with the ammonia to form butyl carbamate. A derivatized externally sampled internal standard (dESIS) method based upon the reactivity of diethylamine with unreacted butyl chloroformate on the SPME fiber to form butyl diethylcarbamate was established for the reproducible quantification of ammonia concentration. Both of these compounds are easily detectable and separable via GC-MS. The optimized method was then used to quantitate the vapor concentration of ammonia in the headspace of two commonly used improvised explosive device (IED) materials, ammonium nitrate fuel oil (ANFO) and ammonium nitrate aluminum powder (Ammonal), as well as identify the presence of additional fuel components within the headspace.
authors.affiliation: Nova Research, Inc., Alexandria, VA 22308, USA.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Lubrano
authors.affiliation: Nova Research, Inc., Alexandria, VA 22308, USA.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Andrews
authors.affiliation: Chemistry Division, U.S. Naval Research Laboratory, Washington D.C. 20375, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Hammond
authors.affiliation: Chemistry Division, U.S. Naval Research Laboratory, Washington D.C. 20375, USA.
authors.forename: Greg E
authors.initials: GE
authors.lastname: Collins
authors.affiliation: Chemistry Division, U.S. Naval Research Laboratory, Washington D.C. 20375, USA. Electronic address: susan.rosepehrsson@nrl.navy.mil.
authors.forename: Susan
authors.initials: S
authors.lastname: Rose-Pehrsson
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D009566:Nitrates / Q000032:analysis*; D052617:Solid Phase Microextraction
chemical_list: D009566:Nitrates; C006568:ammonium nitrate
keywords: Ammonium nitrate fuel oil; Butyl chloroformate; Gas chromatography–mass spectrometry; Solid phase microextraction