The techniques and instrumentation routinely used include presumptive color tests, microscopic examination, Gas Chromatography/Mass Spectrometry (GC/MS), Fourier Transform Infrared Spectroscopy (FTIR) and High Performance Liquid Chromatography/Mass Spectrometry (LC/MS).
Controlled Substance Analysis
The St. Louis County Police Crime Laboratory Drug Chemistry section tests a variety of evidentiary items for the presence of controlled substances. Items tested include powders, liquids, plant material, tablets, capsules, pharmaceuticals, and various forms of paraphernalia. Forensic chemists routinely confirm substances such as marijuana, heroin, Fentanyl, methamphetamine, cocaine HCL/cocaine base, pharmaceuticals, anabolic steroids, and synthetic cannabinoids, while also confirming lesser known designer drugs and final product/ precursor components from suspected clandestine laboratories. Forensic chemists rely on State of Missouri and Federal statutes to determine whether or not an identified substance is controlled.
Fire Debris Analysis
The Chemistry Section of the St. Louis County Police Crime Laboratory also conducts analysis of fire debris. Fire debris analysis includes testing of evidentiary items associated with fire scenes for the presence of ignitable liquids. Items tested vary from liquids to charred debris and include items such as carpet/flooring, clothing, debris from automobile fires, and liquids removed from ignitable liquid containers and gas cans. Using current techniques and instrumentation, forensic chemists can determine if an ignitable liquid is present in submitted fire debris evidence. Since petroleum-based products are everywhere in our society, the forensic chemist needs to understand matrix interferences and contributions. Ignitable liquids can also be inherent to the matrix which complicates the interpretation of the data. Using GC/MS instrumentation, forensic chemists are able to identify ignitable liquids into 8 different classifications (i.e. petroleum distillate, gasoline, naphthenic paraffinic, etc.) and 3 sub-classes (i.e. light, medium, heavy). Individual ignitable liquid brands cannot be determined.
The Chemistry Section also provides region wide forensic support to the St. Louis Regional Bomb and Arson Unit. Using instrumentation such as GC/MS, FTIR, LC/MS, IC/MS, XRD, SEM-EDS and Stereomicroscopy forensic chemists are able to conduct analysis on explosives evidence to identify the presence of explosives or explosive precursors. These may include Black Powder, Black Powder Substitutes, Smokeless Powders, Improvised explosive mixtures, and many other classes of explosives. These analyses can help the Bomb and Arson Detectives determine the type of explosives used, connect a person to an explosives crime, or determine the presence of a clandestine explosives laboratory or manufacturing process. Chemists can also provide technical assistance to Bomb Technicians as they identify, process, and dispose of explosive threats.