Detection of High Explosives Using Reflection Absorption Infrared Spectroscopy with Fiber Coupled Grazing Angle Probe/FTIR

Abstract

Fiber Optic Coupled Reflection/Absorption Infrared Spectroscopy (RAIRS) has been investigated as a potential technique for developing methodologies of detection and quantification of explosive residues on metallic surfaces. TNT, DNT, HMX, PETN, and Tetryl were detected at loading concentrations less than 400 ng/cm 2 . Data were analyzed using Chemometrics statistical analysis routines. In particular, partial least squares multivariate analysis (PLS) was used for quantification studies. Peak areas were also used for data analysis to compare with linear multivariate analysis. The measurements resulted in intense absorption bands in the fingerprint region of the infrared spectrum that were used to quantify the target threat chemicals and to calculate the limit of detection for each compound. Micro-RAIRS vibrational imaging was also used for characterization of the distribution and form of layers of explosives deposited on stainless steel sheets. The degree of homogeneity depended strongly on the method of deposition. The images were generated by calculating the area under vibrational signals of 15 lm 9 15 lm grids with a separation of 15 lm. Histograms of the maps were generated and the homogeneity was evaluated by using standard deviations, mean kurtosis, skewness, and moments of distributions obtained. Methanol solutions of High Explosives (HE) resulted in the optimum distributions on the stainless steel surfaces tested and therefore, Methanol selected as the preferred solvent for the Fiber Optics Coupled-RAIRS experiments.

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

“…LODs between 160 and 400 ng cm −2 have been reported for TNT, tetryl, PETN, DNT, and HMX. (69) This technique does not provide substantial standoff features.…”

Applications of Fiber Optic Coupled-Grazing Angle Probe Reflection-Absorption FTIR Spectroscopy

“…FOP-GAP FTIR absorption-reflection spectroscopy may be successfully implemented in assessing sample loading distribution of solids deposited on substrates (Primera-Pedrozo, 2008;Primera-Pedrozo, 2009 This method is rapid and easily executed without specialized equipment. The amount is readily controlled and can be calculated without the need for an independent analysis.…”

Preparation of TNT, RDX and Ammonium Nitrate Standards on Gold-on-Silicon Surfaces by Thermal Inkjet Technology

“…Several analytical techniques have been used to ensure reliable and reproducible in situ trace HEM detection. Among these techniques, ion mobility spectrometry (IMS) [3][4][5][6], secondary ion mass spectrometry (SIMS) [1] and fiber optic coupled grazing angle probe/Fourier transform reflection absorption infrared spectroscopy (FOC-GAP/FT-RAIRS) [7][8][9][10] have been used the most frequently. In the first two techniques, chemical analysis takes place after sample collection.…”

“…Sample smearing [7,8,12,13], aerosol spray deposition, thermal inkjet deposition [14], deposition by rotary evaporation [15], and direct transfer deposition using micropipettes [14] have been reported previously as methods for sample and standards preparation on metals, silica, glass and plastic surfaces. Also, trinitrotoluene (TNT) was deposited on cloth and planar surfaces with post removal by air jets.…”

“…In previous works, it was demonstrated that TIJ technology can be used for depositing 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX) onto stainless steel surfaces, and TIJ-based deposition has been shown to be a superior method for further detection using FOC-GAP/FT-RAIRS [7,8]. Visualization of deposits, using optical microscopy images, showed that there was a close dependence between the number of passes and the crystallization of the explosives on the surface [14].…”