A comparison of solvent extract cleanup procedures in the analysis of organic explosives

The use of an organic solvent to extract explosive residues from hand swabs and postblast debris inevitably leads to the coextraction of unwanted materials, usually in far greater quantities than any explosive residue. In this study, the extraction efficiency of a number of solvent cleanup procedures including solid-phase extraction (SPE), adsorbent resins such as Chromosorb-104, and traditional materials such as silica and Florisil was calculated using a quantitative liquid chromatography-ultraviolet (LC-UV) detection procedure. The Oasis(®) HLB cartridge outperformed other cleanup procedures, with analyte recoveries approaching 95%, while the Amberlite XAD-7 procedure returned the lowest overall recoveries. The matrix rejection ability of each method was then determined using a simulated highly contaminated matrix, with the adsorbent resins showing a higher degree of matrix rejection, which is seen as a reduction in background noise in the UV chromatogram using 210 nm detection.