An analysis of the accuracy and function of three presumptive methods used in forensic science for the detection of urine
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Abstract
The presumptive detection of urine from evidence found at a crime scene can assist investigators in determining the events that occurred during the commission of the crime. The Jaffe test is a traditional method which relies on the detection of creatinine, a constituent of urine. In 2009, the Uritrace® test device was developed to detect the presence of creatinine in urine. In 2010, the RSIDTM-Urine immunochromatographic card was released as a method for detection of a reportedly more specific component of urine, Tamm-Horsfall protein. The significance of these various techniques lies in their capacity to accurately detect the respective urinary constituents to allow for a presumptive determination of urine.
The objective of this study is to compare the three presumptive tests to determine how effectively and accurately each method could be used to detect their respective target molecules in urine. Areas of research interest include the area of the stain that is sampled, manipulation of buffer volumes, the level of cross-reactivity with non-urine samples, and the detection of nucleated epithelial cells in aged urine stains. It was discovered that, with regards to the Jaffe and Uritrace® methods, the area in which the known urine stain was sampled did not affect the result of the test; however that was not the case for RSIDTM-Urine. Decreasing the extraction volume for Uritrace® and RSIDTM-Urine did not inhibit positive results, implicating that it is possible to adequately perform either of the tests at lower levels of dilution. Jaffe and Uritrace® were shown to be susceptible to false positive signals, whereas RSIDTM-Urine was not. Nucleated epithelial cells were not detected in any of the aged urine stain samples, suggesting that the persistence of cellular material available for potential downstream DNA testing may be minimal. Photoimaging analysis was also used to assess the ease of interpretation of results using Uritrace®. An evaluation of all three methods revealed that although the Jaffe test is not the most specific method, it is the most practical and cost-effective method for the forensic detection of urine.
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Thesis (M.S.)--Boston University
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