4196975 - Feasibility of the brand identification of pepper gels via FTIR-ATR and GC/MS

The purpose of my research is to test the feasibility of the FTIR-ATR and GC/MS to differentiate five different pepper gels and to determine the amount of time pepper gels can no longer be detected on each instrument by leaving the samples out for various timeframes on different textiles. Pepper gels are a viscous pressurized solution intended for self-defense usage. The active ingredient in pepper gel is oleoresin capsicum (OC), which is made up of different capsaicinoids, such as capsaicin and dihydrocapsaicin. OC is derived from the peppers of various pepper plants. OC has the potential to render a person incapacitated anywhere between 10-15 minutes by irritating a person’s airways, eyes, and nasal cavities. Although pepper gels are commonly used as self-defense when a perpetrator attacks a victim, the perpetrator can also use it antagonistically to render the victim incapacitated to further harm the victim. In both cases, a link is created between the victim/perpetrator and the pepper gel. Pepper gels can also be used in crime scene reconstruction by determining the origin of the attack.
Currently, there is no published research on pepper gels, only on pepper spray. Although similar, pepper gel differs in its composition. Pepper spray is an aerosol solution while pepper gel is viscous and can travel a further distance. It was designed this way for the purpose of preventing wind blowback into the user’s face, thus preventing harm to them in the process of using the spray.
We sprayed pepper gel on cotton, polyester, and rayon textiles then extracted them at 1, 2, 4, and 6 weeks. We report on the analysis of each using ATR-FTIR and GC/MS and differentiation of the brands using discriminant function analysis. We further determined the LOD for capsaicin using GC/MS. This research will benefit local laboratories by creating a timeframe for when pepper gel samples must be analyzed before the sample is lost. Sample backlog is a problem within many laboratories due to a high number of various samples coming in, therefore, by finding the timeframe in which a sample is no longer able to be differentiated, it would help the laboratory focus on more important samples before having to worry about their pepper gel samples degrading before having a chance to analyze them. Future studies could utilize artificial intelligence to compound the data and create databases for laboratories to use.