Toward maintaining canine training aid integrity: Visualizing contamination and testing storage materials for a non-hazardous canine training aid.

Contamination of canine training aids is a pervasive issue that may lead to incorrect canine discrimination of target odors. It is therefore important to properly store training materials to maintain their integrity and efficiency. First, this study demonstrated the potential for contamination using GloGerm™ as a proxy for odor/particulate transfer. Then, eight types of containers were evaluated to determine (1) the ability to prevent odor permeation and (2) the likelihood of maintaining the ab/adsorbed odor. Lastly, a longitudinal study evaluated how the permeation of the target odor changed over time. Analysis occurred using a direct analysis in real-time mass spectrometer (DART-MS) to detect triacetone triperoxide (TATP) from the non-hazardous canine training aid known as the polymer odor capture-and-release (POCR) system. Results showed that Mylar and Opsak bags were most effective for short-term storage, maintaining low levels of ab/adsorption. Over time, the amount of TATP permeating through the primary containers and collecting in a secondary container (i.e., outer packaging) increased at 1 week and decreased thereafter (up to 4 months). The amount of TATP collecting in the primary containers, however, increased up to 1 month and decreased thereafter.

Permeation of human scent through laboratory examination gloves.

It is generally accepted in the canine detection industry that a barrier (such as a glove) should be used between a human and evidence or canine training aids in order to prevent contamination and cross-contamination as well as protect the handler from hazardous materials. However, no studies exist evaluating this assumption. Further, there is no published literature examining the different types of gloves for their utility in handling evidence or training materials used in canine detection work. This study was the first of its kind to address these gaps in the literature. First, GloGerm™ was used as a proxy for human scent and odor(s)/particulate(s) to visualize potential contamination. Then, three types of gloves (nitrile, two layers of nitrile, latex, and polyethylene) were tested for the permeation of human scent using furfural as a proof of concept, followed by pooled human sweat. Finally, the inherent odor of each glove type was identified. Two analytical techniques were used simultaneously as static and standoff dynamic detection systems, respectively: solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and direct analysis in real time-mass spectrometry (DART-MS). Using a double layer of nitrile gloves was the most effective in preventing furfural permeation from the analytical standard, while a single layer of nitrile prevented furfural from permeating from human sweat up to 2 h. Polyethylene gloves allowed the highest amount of furfural permeation but had no inherent odor detected. Headspace analysis detected two compounds for nitrile gloves and four compounds for latex gloves, but the nitrile compounds had a higher relative abundance.

Development of a body fluid identification multiplex via DNA methylation analysis.

The goal of this study is to develop an epigenetic multiplex for body fluid identification based on tissue specific DNA methylation. A series of genetic loci capable of discerning the origin of DNA as coming from saliva, blood, vaginal epithelia, or semen were used for this application. The markers - BCAS4, CG06379435, VE_8, and ZC3H12D - were amplified together and then sequenced via pyrosequencing. Methylation values for cytosine guanine dinucleotide (CpG) sites at each locus were then measured across the four markers. In total, 124 samples were collected, and bisulfite modified to convert unmethylated DNA to uracil. This converted DNA was then amplified via multiplex PCR with reverse primers containing a biotin molecule. Biotinylated PCR products were then analyzed using pyrosequencing to generate a series of pyrograms containing 18 CpG sites. The percent methylation at each CpG site was determined, and then agglomerative hierarchical cluster analysis was used to create a model to indicate sample origin. Further analysis reduced the number of CpG sites required for optimal determination of body fluid type to five. This study demonstrates an efficient multiplexed body fluid identification process utilizing DNA methylation that can be easily implemented in forensic laboratories.