Date of Submission
Alyssa Marsico, Ph.D.
Cosmetic Hair Treatments, Permanent Oxidative Hair Dye, Attenuated Total Reflection, ATR-FTIR, GC-MS
Hair--Analysis, Forensic sciences, Amino acids--Analysis, Hair--Dyeing and bleaching, Laser-induced breakdown spectroscopy--Forensic applications, Gas chromatography--Forensic applications, Mass spectrometry--Forensic applications, Fourier transform infrared spectroscopy
Hair is a forensically-relevant exhibit due to its ability to be shed, torn, or transferred during a crime. Current forensic hair analysis includes microscopic hair comparison and mitochondrial or nuclear DNA analyses, each with limitations. Novel methods, such as those evaluated herein, have potential to complement conventional techniques. These include evaluating functional groups with infrared (IR) spectroscopy, elements with laser induced breakdown spectroscopy (LIBS), and amino acid ratios with gas chromatography- mass spectrometry (GC-MS). Hair from two demographically similar individuals was divided into three sample groups per individual: untreated, bleached, and dyed. Spectral differences between individuals and treatments were evaluated with IR. Five of eleven bands differed between individuals, and seven bands differed after treatment. LIBS analysis revealed calcium, potassium, and sodium to be significantly different among individuals. Decreases in carbon, nitrogen, oxygen, and hydrogen were observed after treatments. Six derivatized amino acids were identified with GC-MS to produce fifteen amino acid ratios. One ratio was found to be significantly different among individuals. Additional significant differences would likely surface with retesting. Complications with GC-MS made comparisons between individuals and treatments difficult. individual 2 displayed lower variances, so comparisons between treatments were based on their data. For individual 2, three amino acid ratios were found to be significantly different after bleaching, while none were after dyeing. Variances in GC-MS analysis made the amino acid ratio stability after treatments difficult to establish. Further research is required to better understand the effects of chemical treatments on elements, functional groups, and amino acids.
Brady, Trisha, "Amino Acid Composition Analysis as a Means to Differentiate Hair Samples from Individuals of Similar Demographics and the Effect of Hair Treatments" (2021). Honors Theses. 7.