This paper examines efforts to use surface-enhanced Raman spectroscopy techniques for the identification, classification, and quantification of drug chemistry and toxicology in forensic investigations that require the analysis of mixtures with low weight percent contributions of analytes, as well as in forensic toxicology where matrix inferences, sensitivity requirements, and increasing numbers of novel drug entities pose challenges.
Applications and advances in surface-enhanced Raman spectroscopy (SERS) have grown over the last several years, demonstrating improvements in sensitivity and selectivity. Applications for SERS-related techniques have been explored in many analytical disciplines, including forensic applications. Drug chemistry and toxicology may benefit from the growth of SERS since many methods have demonstrated high sensitivity, potential for quantitative analysis, and portable instrumentation for onsite testing. SERS techniques have been developed using many substrates including nanoparticles and colloids; microfluidic devices; paper-based substrates; electrodes; and wearable/flexible devices. These methods take advantage of the SERS phenomenon, providing more potential applications for Raman analysis and overcoming the traditional challenges of the technique. This is desirable for forensic drug chemistry applications which require screening and confirmatory approaches and analysis of mixtures with low weight percent contributions of analytes, as well as forensic toxicology, where matrix interferences, sensitivity requirements, and a growing introduction of novel drug entities pose challenges. Several chemometric approaches have been applied to Raman data to improve identification, classification, and quantification. These advances position SERS for incorporation into forensic chemistry laboratories. While some SERS applications are available commercially, widespread use of SERS in practicing forensic laboratories remains limited. Due to the requirements for use of analytical techniques in the courtroom, future studies for SERS should revolve around the assessment of validation parameters common in other analytical methods. SERS techniques that are rapid, simple, and inexpensive may be more quickly adapted for forensic testing, where use as advanced screening techniques is a clear avenue of research. (Published Abstract Provided)