Targeted fentanyl screening utilizing electrochemical surface-enhanced Raman spectroscopy (EC-SERS) applied to authentic seized drug casework samples

Abstract

Effective and rapid screening methods for seized drug analysis are crucial to ensure the safety of first responders and laboratory personnel, while reducing overall analysis time and improving reliability. The drug landscape has been overwhelmed by fentanyl and fentanyl analogs that are extremely potent and generally present in low concentrations with other drugs and diluents. We have previously reported the use of electrochemical surface-enhanced Raman spectroscopy (EC-SERS) as a novel screening method for detecting fentanyl and fentanyl analogs in the presence of commonly encountered analytes. Herein, we present the application of this targeted method to authentic seized drug casework samples to assess the performance and fit-for-purpose of the developed method to accurately identify fentanyl and fentanyl-like substances. Authentic sample sets contained a wide range of analytes, and a varying number of compounds present in each sample, representing both true positive and true negative samples. EC-SERS results were compared to the ground-truth as established by gas chromatography-mass spectrometry (GC–MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), as well as the results of chemical color tests. Application to authentic samples allowed for identification of fentanyl and fentanyl analogs. The targeted approach was shown to provide preferential enhancement of the fentanyl signal. The overall accuracy for the targeted screening method for the presence of a fentanyl/fentanyl-like substance was 87.5 % and the fentanyl samples averaged between 6 wt% to 9 wt% fentanyl or fentanyl analog. EC-SERS provided an alternative fentanyl screening approach demonstrating results within minutes and the absence of false positives.