Transport of explosives II: use of headspace-SPME/GC μ-ECD and TEEM GC/MS for detection of TNT vapors from sand buried samples

Abstract

The detection of hidden explosives using vapors emanating from explosives has been considered an area in explosives technology that requires high sensitivity and selectivity. In this work is reported the results of two methods for vapor explosive detection, GC-μECD and GC/MS coupled to a Tunable Electron Energy Monochromator (TEEM-GC/MS). Both used Solid Phase Microextraction (SPME) in Headspace (HS) mode to collect vapors above the samples. Optimum parameters for SPME were determined with the purpose of obtaining a high-quality extraction. The parameters were: type of SPME fiber, exposure time and desorption time at the injection port of the GC. Headspace SPME procedure was carried out in samples with crystals of TNT buried in soil. These samples were analyzed under important environmental conditions such as temperature and water content. Analyses at contact times after the TNT-soil mix preparation were carried out during 1 month. A comparison of results from both techniques was performed. Vapors of TNT and 2,4-DNT were found predominantly in the samples. HS-SPME coupled with GC-μ ECD and TEEM GC/MS exhibited excellent selectivity and sensitivity.