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Current Research Projects

1. Determination of Post-mortem Interval by Analysis of Citrate Content of Bone

The reliable and accurate determination of the post-mortem interval (PMI) continues to be a major problem in forensic science. The PMI is a crucial piece of information for forensic scientists and medicolegal investigators, since knowledge of the PMI can lead to identification of victim(s) and/or suspects in criminal cases by establishing the time dimension in investigations. For practical purposes, remains with a PMI <50 years old are typically deemed forensically relevant, while older remains would be considered to be historic. Current chemical methods (e.g., luminol or radiodecay) lack the accuracy and/or precision necessary to provide reliable PMI values. Schwarcz et al. (2010) have suggested that citrate in bone decreases in concentration with an increase in PMI and that the rate does not depend significantly on storage conditions. This method may provide a promising approach to PMI determination of skeletal remains; therefore it warrants further investigation. The main goal of this project is to further optimize and develop the method of Schwarcz et al. and apply it to the analysis of human bone samples with known PMI. Analysis of fresh and aged pig bone samples under controlled conditions is ongoing, to obtain a composite baseline from fresh samples for citrate content and test citrate decrease in aged samples. Dr. Brown is collaborating with Dr. Ann Bunch (Brockport Criminal Justice Department) on this project. Student researcher(s) working on this project are currently developing an HPLC method for the determination of citrate content of bone samples, optimizing sample preparation procedures, and validating of Schwarcz's work.

2. Determination of Disinfection By-product Concentrations in Drinking Water using Membrane-based GC-MS

Water chlorination is an effective process for preventing water borne diseases, yet forms halogenated disinfection by-products (DBPs) from the reaction of natural organic matter with free available chlorine.1, 2 The two main classes of DBPs are the trihalomethanes (THMs) and the haloacetic acids (HAAs). These compounds are considered to be possible carcinogens, so are regulated by the USEPA in finished drinking water. Current methods of analysis for THMs work well, but often require organic solvents or expensive sampling systems to perform. The main goal of this project is to use an alternative, solvent free membrane-based gas chromatography-mass spectrometry (GC-MS) method to determine DBP concentrations in drinking water samples. The membrane sampling device3, 4 employed in this research is comprised of two stainless steel tee unions and a Tefzel® tubing shell with polymeric membrane tubing inserted inside. When drinking water flows through the device, volatile compounds in the water permeate through the membrane walls and into an inert gas stream. The enriched gas stream is then analyzed by a GC-MS instrument (Figure 1).4

Figure 1. Membrane sampling device interfaced to a GC-MS instrument.

Student researcher(s) who have worked on this project gained experience using a GC-MS instrument, learned to optimize method parameters and conditions, perform calibration studies (e.g. external and internal standard), conduct matrix spiking studies, and apply the method to the analysis of drinking water samples.

[1] Rook, J. J. (1974). Water Treatment and Examination, 23, 234–243.
[2] Krasner, S. W., Weinberg, H. S., Richardson, S. D., Pastor, S. J., Chinn, R., Sclimenti, M. J., Onstad, G. D., & Thruston Jr., A. D. (2006). Environmental Science and Technology, 40(23), 7175-7185.
[3] Brown, M. A. & Emmert, G. L. (2006). Analytica Chimica Acta, 555, 75-83.
[4] Emmert, G. L., Brown, M. A., Geme, G., Simone, P., Cao, G. (2007). Project 2873, Awwa Research Foundation.

3. Evaluation of Polymeric Membranes for the Extraction of Volatile Compounds from Drinking Water

Polymeric membranes can be used for a variety of applications including gas and liquid extraction, recovery and purification of organic solvents, and sample introduction for analytical instrumentation. The extraction of volatile, non-polar compounds from a liquid or air matrix is governed by the concentration gradient that exists between the membrane-matrix interfaces (Figure 2). Two main processes are involved in the permeation process. (I) Convection resulting in mass flow in the axial direction and (II) Diffusion resulting in mass flow in the radial direction with respect to tubing walls.1- 3 For analytical purposes, steady state conditions (Fick's 1st law) should be satisfied as fast as possible to reduce sampling times. The main goal of this project is to evaluate various polymeric membranes for the extraction of volatile compounds from drinking water. A membrane, which can rapidly, selectively, and reproducibly extract analytes is desired. Student researcher(s) who have worked on this project evaluated both non-porous and porous membranes, gained experience using a membrane introduction flame ionization detection system, and learned to use mathematical modeling/computational software.

Figure 2. Conceptual diagram of the diffusion process concentration of molecule in acceptor gas (Cg) concentration of molecule in solution (Cs).

The student researcher(s) working on this project will conduct a literature survey, evaluate both non-porous and porous membranes, gain experience using a membrane introduction flame ionization detection system, and learn to use mathematical modeling software.

[1] Sysoev, A. A. (2000). Analytical Chemistry, 72, 4221-4229.
[2] LaPack, M. A., Tou, J. C., & Enke, C. G. (1990). Analytical Chemistry, 62, 1265-1271.
[3] Boscaini, E., Alexander, M. L., Prazeller, P., Märk, T. D. (2004), International Journal of Mass Spectrometry. 239, 179-186.