Improved explosive collection and detection with rationally assembled surface sampling materials

Sampling and detection of trace explosives are critical steps in the analytical process necessary for modern transportation safety. In this work we have explored some of the fundamental aspects that influence collection and detection of trace levels of explosive residues from surfaces. We compared the analyte-release performance of standard muslin sampling swipes to that of rationally assembled fiberglass cloth, and used thermal-desorption ion mobility spectroscopy for detection. This collection–detection system is widely used for analyzing the trace chemical residues. The fiberglass cloth was chemically modified by covalently bonding phenyl-functional groups to the surface. The rationally assembled sampling materials provide significantly performance improvements over standard muslin sampling materials for detection of TNT, NG, RDX, TATP, and PETN. The phenyl-functionalized fiberglass swipes showed over 10 times greater TNT release, compared to muslin sampling swipes, as well as improved response and repeatability after multiple uses of the same swipe. The improved TNT release from the functionalized-fiberglass swipes resulted in significantly improved detection limits over muslin. To better understand the improvement offered by the phenyl-functionalized fiberglass, several commercially available fiberglass materials, each offering specific characteristics, were also compared, allowing several physical and chemical properties to be systematically explored to determine their influence on performance. These results are relevant to improving the detection of other explosive compounds, and potentially to a wider range of chemical sampling from surfaces.