The coupling of capillary microextraction of volatiles (CMV) dynamic air sampling device with DART-MS analysis for the detection of gunshot residues

Abstract A novel apparatus interfacing capillary microextraction of volatiles (CMV) and direct analysis in real time mass spectrometry (DART-MS) was evaluated for the trace detection and characterization of organic compounds found in smokeless powders and consequently in gunshot residues (GSR). Target analytes included nitroglycerin (NG), diphenylamine (DPA), ethyl centralite (EC), 2,4-dinitrotoluenes (2,4-DNT), methyl centralite (MC), 2,4,6-trinitrotoluene (2,4,6-TNT) and derivatives of DPA generated from the degradation of the energetic material such as 4-nitrosodiphenylamine (4-NODPA), 2-nitrodiphenylamine (2-NDPA) and 4-nitrodiphenylamine (4-NDPA). The results from CMV-DART-MS were compared to the previously reported CMV-GC–MS method through the application of an efficient and calibrated vapor source based on an inert pre-heated GC split/splitless injector port, to simulate field sampling of GSR in the air surrounding a person’s hands. It was found that both DART-MS and GC–MS could be used in succession to detect a suite of compounds at 15 ng sampled vapor within 2.5 L of air to provide more comprehensive characterization of a sample. Overall, a method was developed for the analysis of compounds associated with GSR applying fast, dynamic air sampling (2–5 min) using the CMV device coupled for the first time to DART-MS for fast analysis (∼1 min), compared to GC–MS results under the same sampling conditions of ng quantities of the target analytes of interest.