Electrochemical Characterization of Fentanyl for Forensic Analysis

Abstract

The use and abuse of fentanyl has risen drastically over the last several decades. The abuse of this substance has created a hazardous situation for law enforcement and first responders because they could arrive at locations and not necessarily know that they will encounter fentanyl or a fentanyl analog. Fentanyl analogs are substances that have a similar structure to fentanyl, and while the analogs may have additional or altered groups on the molecule, the backbone structure remains similar. This work focus on the electrochemical characterization of fentanyl as a stepping stone for the detection of both fentanyl and later fentanyl analogs by electrochemistry. The metabolic reaction of fentanyl is an N-dealkylation to norfentanyl, occurring in the liver, and can be mimicked by electrochemistry through the irreversible oxidation of fentanyl. This electrochemical reaction is hypothesized to generate electroactive metabolites in solution. The combination of the visualization of both the irreversible oxidation with the development of the additional metabolic electrochemical peaks would constitute a unique electrochemical signature for fentanyl and fentanyl analogs towards a universal rapid screening assay. The electrochemical behavior of fentanyl was characterized in depth using multiple electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). The optimization of the supporting electrolyte, the potential range, and methods to decrease the background current were explored with CV. To work towards a more portable system, screen printed electrodes were used. The observation of the metabolic peaks remained challenging, and different methods were attempted to achieve it. The quantification of fentanyl was successfully demonstrated using the different electrochemical systems proposed in this work. The electrochemical characterization of fentanyl and the optimization of multiple experimental parameters were the first step in developing a universal, rapid, electrochemical sensing method for the detection of fentanyl and fentanyl analogs.