Responding to changes in the unregulated drug supply: the need for a dynamic approach to drug checking technologies

Figures & data

Figure 1. Schematic illustrations of surface enhanced Raman spectroscopy (a) and paper-spray mass spectrometer. (b) Created with BioRender.com. Adapted from Zheng and He (32).

Table 1. Comparison of recently deployed point of care drug-checking technologies: Fourier-transform infrared spectroscopy, paper spray mass spectrometry, and surface-enhanced Raman spectroscopy.

Technology	Mechanism	Potential Application	Sample Requirement	Portability, Time to Results	Future Directions
Immunoassay strips	Target compound immunoassay	Able to detect target and closely related compounds at trace concentration in solution Sensitive, disposable, can be widely distributed and used with minimal training	Less than 5 mg of sample that is dissolved in water	Portable, provides results within 2 minutes	Future research into cross-reactivity and validation of non-fentanyl targeted strips
Fourier-transform infrared spectroscopy (FTIR)	Mid-range infrared spectroscopy	Able to detect psychoactive active and inert substances with references in libraries Able to detect substances above a concentration of 5% (w/w%)	Less than 5 mg of sample that can be returned	Portable, provides results within 5 minutes	Further research on quantification methods and neural network modelling
Paper spray mass spectrometry (PS-MS)	Paper spray ionization and mass spectrometry	Able to detect novel psychoactive substances outside of a preset library of spectra Able to detect fentanyl and fentanyl analogues at lower concentrations than immunoassay strips and FTIR	Less than 1 mg of sample is required	Portable, provides results within 5 minutes	Further research on the feasibility outside of the context of pilot studies are needed
Surface enhanced Raman spectroscopy (SERS)	Raman spectroscopy using a roughened surface with metallic nanoparticles to enhance sensitivity	Able to detect etizolam in the unregulated supply Highly sensitive, compared to FITR and immunoassay strips	Small amount of sample required	Portable, provides results within minutes	Further research on the feasibility outside of the context of pilot studies are needed

Zheng J, He L. Surface-enhanced raman spectroscopy for the chemical analysis of food. Compr Rev Food Sci Food Saf. 2014;13:317–28. doi:10.1111/1541-4337.12062.

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