Evaluation of solid-phase extraction (SPE) systems for the recovery of smokeless powder (SLP) residues from swabs with a proof-of-concept comparison between gloves and bare hands

Smokeless powders (SLPs) are widely used in improvised explosive devices, and understanding the transfer and persistence of their residues is central to assessing activity-level scenarios. While direct GC–MS approaches such as filter-and-shoot (F&S) have been proposed to quantify residue transfer on hands under controlled conditions, their applicability to more complex scenarios may be limited. This study presents the development and evaluation of a solid-phase extraction (SPE) method to enhance the analysis of SLP additives from swabs. The protocol was systematically optimised for cartridge type and elution solvent, identifying Oasis HLB combined with either acetone or ethyl acetate as effective configurations. Both systems yielded near-complete recoveries across all target compounds, confirming their suitability for quantitative trace analysis. The ethyl acetate variant was benchmarked against the existing F&S workflow. Comparable or improved sensitivity was achieved across all target analytes, with method detection limit reductions of up to 8.2-fold. In addition, representative chromatograms demonstrated a reduction in background signals following SPE, supporting its potential for handling more contaminated matrices. As a proof of concept, the optimised SPE method was used to compare SLP residue transfer to bare hands versus nitrile gloves after controlled handling, enabling the detection of 2-nitrodiphenylamine, which had not been previously reported under comparable conditions. This experiment also showed consistently higher residue levels on bare skin than on gloves for all detected compounds. Overall, these findings provide a robust platform for future studies on the transfer and persistence of SLP residues and offer empirical support for activity-level evaluations. • SPE method optimised for recovering smokeless powder (SLP) residues from swabs. • Oasis HLB with acetone or ethyl acetate gave high recoveries of all target analytes. • SPE improved sensitivity and lowered background signal compared to filter-and-shoot. • Method applied to real samples comparing residue transfer to bare hands and gloves. • Findings support future studies on SLP residue transfer and persistence.