Stability of smokeless powder compounds on collection devices

The current trend towards the implementation of organic gunshot residue (OGSR) analysis into gunshot residue (GSR) investigation protocols typically involves the sequential analysis of inorganic and organic GSR. However, to allow for the consecutive analysis of inorganic and organic GSR, specimens will often be stored for different lengths of time which may result in compounds of interest degrading. In order to optimise storage conditions, it is important to consider compound degradation on collection devices during storage. This study investigated the degradation over time of compounds potentially present in smokeless powders and OGSR on two collection devices, alcohol swabs and GSR stubs. Over a period of 63 days, the highest degree of degradation was found in the first four days. Interestingly, energetic compounds were generally found to be more stable than smokeless powder additives such as stabilisers including diphenylamine and ethyl centralite, which might be problematic considering that these compounds are common targets for OGSR. The findings can provide valuable information to operational forensic laboratories to optimise their storage durations.