Posted: Monday, October 28, 2013
Fall 2013 Chemistry-Physics Seminar: Raman Microspectroscopy and Advanced Statistics for Forensic Applications
Igor K. Lednev, associate professor of chemistry at the University at Albany, will present his research talk "Raman Microspectroscopy and Advanced Statistics for Forensic Applications" at 12:30 p.m. Thursday, November 7, in Science Building 272. An abstract of his talk appears below.
Before his presentation, from 11:00 to 11:45 a.m., Lednev will converse with undergraduate and graduate students at Buffalo State regarding the graduate program at the University at Albany. This private conversation will be held in Science and Mathematics Complex 201.
This seminar is sponsored by the Auxiliary Services Grant Allocation Committee, the Vice President for Student Affairs Office, and the Faculty-Student Association.
The identification of biological stains recovered at a crime scene is a key part of forensic investigation. Biochemical presumptive and confirmatory tests are destructive, require hazardous and expensive reagents, and/or suffer from cross-reactivity with other biological fluids. Each of these problems has significant negative impacts on efficiency, cost, lead-time, and quality of the forensic investigation. There is no single test that can be used for several body fluids.
We have demonstrated that Raman microspectroscopy combined with advanced statistics has a great potential as easy-to-use, automatic, on-field method for rapid, nondestructive, confirmatory identification of body fluid traces at a crime scene. We have developed a Raman spectroscopic library for identification of all major body fluids, including blood, semen, saliva, vaginal fluid, and sweat. In addition, the ability of the method to differentiate between animal and human blood traces, as well as between venous and menstrual blood, has been shown. The method has been expanded to body fluid mixtures, contaminated traces, and stains on various substrates. Exciting preliminary results on the genetic profiling based on Raman signature of blood and semen will be also discussed.
Near-infrared (NIR) Raman microspectroscopy and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR) combined with advanced statistics was also utilized for detection, characterization, and identification of gunshot residue (GSR). The firearm discharge process is analogous to a complex chemical reaction. The reagents of this process are represented by the chemical composition of the ammunition, firearm, and cartridge case. The specific firearm parameters determine the conditions of the reaction and thus the subsequent product, GSR. We found that Raman and IR spectra collected from these products are characteristic for different caliber ammunition. This study demonstrates for the first time that vibrational spectroscopy has the potential for the differentiation of GSR based upon forensically relevant parameters, such as caliber size.
A new concept of multidimensional spectroscopic signature and adequate software have been introduced and developed to take into account the intrinsic sample heterogeneity. This concept improves the identification and differentiation power of the method and could be applied for a variety of practical problems involving heterogeneous sample.