Browsing School, Graduate by Author "LaCourse, William R., 1957-"
Detection of Adulteration in Commercial Fruit JuicesWilson, Melinda K.; LaCourse, William R., 1957- (2011)Food safety and security remains an under investigated forensic problem. The US Department of Agriculture (USDA) and the Food and Drug Administration (FDA) examine close to 42 million imports per year, with a mere one percent being tested in a laboratory. These tests are often laborious, complicated, and time consuming with the consequence of economically motivated adulteration (EMA) products entering the consumer marketplace. EMA Is estimated by the Grocery Manufacturers Association to cost from $10-$15 billion per year, much of which is passed directly to the consumer. Fruit juice adulteration occurs when a more expensive product is diluted with a less expensive juice for an economic advantage. Acai juice is made from the berries of the acai palm, and is a major cash crop in the Amazon River region of South America. Due to the fragile nature of these berries, the expensive processing to create the juice, and the high importation costs, acai juice remains a target for adulteration by unscrupulous suppliers. The juice of these berries has a unique organic acid profile, which imparts the tartness of flavor and stability to the juice. This research uses high performance anion exchange chromatography followed by suppressed conductivity detection to profile the organic acids as a means to detect product authenticity. The linear range of this method spanned 0.2 μg/mL to 100 μg/mL for the nine investigated organic acids. The limit of detection for this assay was 0.1 μg/mL with a limit of quantitation of 0.2 μg/mL. Novel aspects of this research include the use of relative retention times to improve reproducibility, high throughput, and little to no sample preparation. This method allows for the establishment of the organic acid profile of a?ai juice as well as other juices. It also allows for the determination of the single strength, mixed juice, and adulterated juices. Importantly, this work can be expanded into other juices. The forensic utility of this method is highlighted by the successful determination of adulteration in a two juice blend.
The Development of a Gas Chromatography/Mass Spectrometry (GC/MS) Method for the Separation and Identification of Components of Organic Gunshot Residue and Its Use as a Forensic Tool for Association of Firearms Related EvidenceTobin, John Joseph, Jr.; LaCourse, William R., 1957-; Squibb, Katherine S. (2012)The use of methods that are not only scientifically sound but also conform to the precepts of the Frye and Daubert legal standards is paramount in the forensic science disciplines. This research develops a method of analysis that can be used by the smaller forensic crime laboratory in the analysis of evidence associated with smokeless powder composition and its organic gunshot residue (OGSR). The method specifically focuses on the separation and identification of the organic additives of the propellant mixture found in handgun ammunitions and their discharge products via gas chromatography/mass spectrometry (GC/MS) using the SIM Mode. The specific ammunition used in this research is Federal Classic 9 mm Luger, 115 gr Hi-Shok. The developed method addresses the following forensic concerns: 1. The identification of organic additive components of smokeless powder that have been removed from the hands of the shooter and compared with the residues remaining in the spent cartridge casings that may be found at a crime scene as well as the components of the unburned propellant. 2. The method demonstrates the use of a proprietary solvent that enhances the collection of the OGSR residues. 3. The method defines the criteria that can be used to determine if the composite analysis of the residue is indicative of the discharge of a firearm. 4. The method studies the longevity/stability of the residues post-discharge and the changes compositional profile, if any. The use of this method in conjunction with the analysis of the inorganic particulate matter will enhance the overall ability of forensic laboratories to identify gunshot residue discharges.