Directed Research Project
Blood is often a type of evidence found at crime scenes. There has been a long history of criminal cases involving blood evidence samples that were allegedly planted at the scene by a third party. Ethylenediaminetetraacetic acid, or EDTA, is an anticoagulant that is not naturally occurring in blood samples; it chelates to ions in blood to prevent clotting. If present in a blood evidence sample, it could be indicative that the blood sample may have been planted at the crime scene to implicate a suspect. EDTA is also reported to modify clothing and exist in detergents, to allow dyes to set and prevent rancidity in soaps. Current techniques for the identification of EDTA include liquid chromatography-tandem mass spectrometry. But this can be an expensive, destructive, and time-consuming method of analysis. Spectroscopic methods like Raman spectroscopy and Fourier-transform infrared spectroscopy (FTIR) provide fast, non-destructive alternative methods to confirm the presence of EDTA in blood evidence. This research aimed to develop methods for both Raman and FTIR spectroscopy to allow for rapid identification of EDTA. FTIR parameters including the number of scans, optical velocity, and resolution were experimented with, to identify the most sensitive method for the identification of EDTA. The optical velocity and resolution were reduced to attempt to increase the sensitivity to EDTA. The number of scans was increased for the same reason. The developed FTIR and Raman spectroscopic methods were suitable for detecting EDTA in water-based standards at concentrations as low as 1.5 mg/mL. EDTA can be observed with peaks reported at approximately 1615 cm-1 and 1401 cm-1. However, these methods were not suitable for confirming the presence of EDTA in blood under normal, expected concentrations of 1-1.5 mg/mL. When analyzing the samples using FTIR, the amide I and II absorption bands present in blood prevented the EDTA bands of interest from being confirmed. Future paths include investigating other anticoagulants like potassium EDTA, heparin, and sodium citrate, and determining whether the amide I and II bands from blood evidence samples can be removed while isolating the EDTA within the sample.
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VCU Master of Science in Forensic Science Directed Research Projects
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