Dual Method Testing Platform for Illicit Drug Identification

NIJ-supported researchers from Illinois State University developed a drug testing prototype that combines paper spray ionization mass spectrometry and surface-enhanced Raman spectroscopy one a single platform for fast and accurate analysis of trace amounts of seized substances.

The platform uses a single paper sample strip for both tests. A copper wire embedded in the paper transfers electrical current to ionize the sample for mass spectrometry. A coating of gold nanoparticles amplifies light scattered by the sample for Raman spectroscopy.

Paper Spray Ionization Mass Spectrometry

An electrical current is applied to the copper wire and generates a spray of ions form the sample that enters the mass spectrometer inlet. Inside the spectrometer, the ions are sorted by weight and a detector captures the pattern of the ions as a spectral signature. The peaks and valleys in the signature indicate elements in the sample, as well as their concentration and relative mass.

Surface Enhanced Raman Spectroscopy

A laser beam causes molecules in the sample to vibrate and scatter the laser light. Gold nanoparticles embedded in the paper amplify the scattering. A Raman detector next to the laser measures the scattered light and translates it into a Raman spectrum. Spikes in the spectrum indicate the shape and orientation of molecules in the sample. These data are particularly important for identifying isomers.

Source: Daniel S. Burr, et al., “Integrating SERS and PSI-MS with Dual Purpose Plasmonic Paper Substrates for On-Site Illicit Drug Confirmation,” Analytical Chemistry 92 (2020): 6676 – 6683.