Coupling Raman Spectroscopy with Ambient Sampling, Portable Mass Spectrometry for On-site, High-Throughput Evidence Confirmation on a Single Instrumental Platform

As submitted by the proposer: Forensic evidentiary backlogs are indicative of the growing need for cost-effective, high-throughput chemical identification methods, and two emerging technologies that show high promise in meeting this need are Raman spectroscopy and paper spray ionization-mass spectrometry (PSI-MS). Both of these techniques are regarded for their discriminating power, denoted by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) as Category A techniques. While portable instrumentation is available for both of these techniques, enabling rapid screening of evidence in the field setting to assist in investigative decision-making, neither individually fulfills the two-tiered identification guidelines recommended by SWGDRUG for generating prosecutorial data. However, development of a portable instrument that integrates two independent, validated techniques would enable field-based, yet court admissible, evidence identification, potentially circumventing the need for off-site laboratory processing and significantly reducing the influx of casework into publicly funded forensic labs. Herein, rapid evidence identification methods will be developed by integrating Raman spectroscopy with a commercially-available, portable mass spectrometer capable of PSI analysis. These proof-of-principle investigations will culminate in a fieldable instrument that is both simplistic in operation and robust to the needs of today’s forensic and law enforcement practitioners, yet capable of yielding prosecutorial chemical information from a single examination of the evidence in question. To extend the applicability of Raman spectroscopy to trace evidence, the required PSI-MS paper substrate will be modified with novel nanoparticle materials that will enable trace detection via surface-enhanced Raman scattering (SERS) processes. This approach leverages unique physical properties of novel nanoparticles for forensic applications, aligning with the U.S. National Nanotechnology Initiative to harness nanoscale science in solving important societal problems. Principle research questions that will be addressed in order to establish proof-of-principle, performance, and impact of the proposed technology include: (i) Can a nanoparticle-modified paper substrate enable trace detection via both SERS and PSI-MS? (ii) Is the analytical performance of the technology on par with currently established methods for forensic evidence processing? (iii) Can the proposed technology be used in the field to collect court-admissible data to circumvent traditional laboratory processing? (iv) Can the proposed technology be adapted for routine and reliable usage by non-technical operators? The deliverable products of this project are diverse, including optimized protocols for synthesizing nanoparticle-modified paper substrates, an analytically-validated, broadly applied evidence screening method via SERS-PSI-MS, and recommendations for its use and adoption in law enforcement and forensic investigations from practical and legal standpoints. Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). ca/ncf