ABSTRACT
The goal of laboratory examination of physical evidence in forensic cases is to help determine or reconstruct the events of a crime, including providing a link between the crime scene(s), victim(s), and suspect(s). Physical evidence can come in various types of forms and materials and the analysis of such evidence frequently involves the characterization of mixtures, some of which can be complex. In some instances, a quantitative analysis of one or more components of the mixture is required. For those compounds that are soluble or have sufficient vapor pressure, the examiner is fortunate to have available one of the most effective analytical separation techniques—gas chromatography (GC). Helium and hydrogen are the most commonly used carrier gases in capillary GC. To promote column life and minimize chromatographic noise, it is imperative that water, hydrocarbon, and oxygen traps be employed in the carrier gas supply lines and that clean hydrogen, air, and makeup gas be used in the case of ionization detectors.
