A Comparison of Common Swabbing Materials for the Recovery of Organic and Inorganic Explosive Residues

The efficiency of solvent based extraction methods used to remove explosive residues from four different swab types was investigated. Known amounts of organic and inorganic residues were spiked onto a swab surface with acetonitrile or ethanol:water combined with ultrasonication or physical manipulation used to extract the residues from each swab. The efficiency of each procedure was then calculated using liquid chromatography‐ultraviolet detection for organic residues and ion chromatography for inorganic residues. Results indicated that acetonitrile combined with physical agitation proved to be the most efficient method; returning analyte recoveries c. 95% for both alcohol based swabs and cotton balls. Inorganic residues were efficiently extracted using ethanol:water, while the use of acetonitrile followed by water significantly reduced the recovery of inorganic residues. Swab storage conditions were then investigated with results indicating decreased storage temperatures are required to retain the more volatile explosives.