CHAPTER 9: Raman Spectroscopy for the Analysis of Novel Psychoactive Substances (NPS)

In this chapter, the use of Raman spectroscopy, a light-based scattering technique, will be examined for its chemical detection of novel psychoactive substances (NPS) in forensic applications. As it is a vibrational technique based on changes in polarisability, Raman spectroscopy has been shown to decipher NPS chemical analogues as well as the NPS from cutting agents and adulterants present in associated products. Analysis can be done in the laboratory or in-field using handheld versions, in which the latter often have in-built matching algorithms for a quick response for non-experts. Analysis can often be carried out through the product packaging (i.e., glass and plastic), however the presence of impurities or cutting agents can lead to high levels of fluorescence which often masks the instrument response from an NPS. Methods for overcoming fluorescence interference includes spectral pre-processing, use of lower energy source radiation, and Surface Enhanced Raman Spectroscopy (SERS). In particular, the availability of handheld Raman spectrometers and the signal enhancements observed for SERS show much potential for application in crime scene investigations.