Using Chromatographic Methods to Assess the Stability of Decomposition Training Aids Under Freezing Storage Conditions for Canine Training Applications

Human remains detection (HRD) canines are a class of odor detection canines trained with training aids representative of distinctive stages of putrefaction. This is necessary for canines to detect the whole spectrum of decomposition products, which is encountered in operational deployments. Understanding the definition of the cadaveric profile can help better train canine detection teams and assist with technological developments. This study aimed to (1) monitor chemical odor profiles utilizing two containment vessels, and (2) monitor two preservation methods on chemical odor profile changes as a function of freezing to thawing cycles. Instrumental analysis used solid phase microextraction- gas chromatography/mass spectrometry (SPME-GC/MS) for identification of volatile organic compounds (VOCs) from tissue/bone samples of pig carcasses at various decomposition stages. Samples were analyzed weekly for six (6) weeks to monitor chemical odor profiles as a function of time. Clear vials provided slightly better storage stability for the fresh stage compared to amber vials. However, amber vials were more suitable for the advanced decay and skeletal stages, helping to preserve the chemical odor profile. Regarding the preservation methods, a continuous preservation method portrayed better reproducibility of the original odor profile throughout the 6-week period, as depicted from higher Spearman correlation values. This study is the first to explore simulated training aids under freezing conditions, uncovering the dynamic and complex nature of odor over time. The results highlight that understanding these shifting odor profiles is essential for canine handlers aiming to optimize the realism and effectiveness of maintenance training.