Many law enforcement agencies process latent fingerprints on plastic bags (e.g., Ziploc) via a glue-fuming technique. Fumes emitted from cyanoacrylate adhesives, such as superglue, react with the moisture in fingerprints to harden and preserve fingerprint ridges. Using gas chromatography/mass spectrometry (GC/MS) and solid-phase microextraction (SPME) to analyze a range of samples from illicit drug investigations, Forensic Science Center (FSC) scientists noticed a significant effect of superglue on plastic bags. Superglue is composed of ethyl cyanoacrylate, polymethyl methacrylate, and hydroquinone. When subjected to the fuming process, these compounds tend to alter the composition of the plastic bag. The team’s experiments detected up to 20 new chemical species that were absent prior to fuming, while another 20 initially present were lost through chemical reaction or were masked from detection by new compounds. Such modifications are important considerations in specifying the exact contents of bagged evidence. Read more about the case.
SPME is used for rapid sampling and analysis of organic molecules such as drugs, explosives, pesticides, toxic chemicals, and chemical-weapons agents. Coupled with GC/MS, this technique has proven to be a powerful method for generating material profiles—notably in methamphetamine samples. The FSC characterized impurities in illicit samples and found traces of a chemical that indicated synthesis via a halogenated ephedrine intermediate. Ethyl vanillin (a flavoring compound) and caffeine (a cutting agent) were also identified. Further analyses detected approximately 30 more organic analytes than were found by GC/MS following an ethyl acetate extraction method that had been adopted by the United Nations International Drug Control Programme. The detection and characterization of increased points of comparison in drug samples allow more selective law enforcement assessments by providing more detailed points of evaluation in chemical signature profiles. Read more about the case.
Oleoresin capsicum (OC), an extract from hot peppers, is the active ingredient in aerosol pepper spray. The use of pepper spray weaponry is considered nonlethal force by law enforcement, but in the 1990s, California experienced a wave of in-custody deaths following pepper spray application. The FSC analyzed natural and synthetic versions of OC preparations to identify the differences. The team used inductively-coupled-plasma mass spectrometry and GC/MS to quantify concentrations of capsaicin and capsaicinoid analogues in natural and synthetic samples, and produced detailed information on the differences in organic and inorganic constituents. Results revealed significant variation in propellants, formulations, and useful shelf-life across the pepper spray manufacturers, leading FSC scientists to recommend additional testing to correlate with weapon effectiveness. Read more about the case.