Improved detection of landmine components: using TEEM-GC-MS for detection of TNT and RDX in soil and other complex matrices

摘要

Nitrogen-rich compounds have a large cross section for resonance electron capture at very low incident electron energies. Although this fact has been known for a number of years, full benefit of this ubiquitous property of NO_X compounds for explosives detection studies has not been fully implemented. Here we report detection of picogram to femtogram levels of TNT, 2,4-DNT and RDX in soil samples and other complex matrices. Toluene extracts as well as thermally desorbed GC-MS analyses were conducted using a JEOL GCmate II coupled to a Tunable-Energy Electron Monochromator (TEEM). Use of TEEM-GC/MS permitted rapid sweeping of electron energy and tuning of the electron monochromator and ion source while monitoring the electron capture resonance in real time. In addition, Solid-Phase Micro-Extraction (SPME) was used to selectively preconcentrate analytes prior conventional GC/MS analysis. The SPME protocol was able to screen explosives in spiked water, in concentrations below the reported detection limits. Standard solutions of TNT were prepared in the range of interest (0.5-10 ppm) and analyzed using a GC/MSD direct injection. Potential use of developed methodology in landmine environmental studies and sensors development will be discussed.