Ionic Liquid-Modified Disposable Electrochemical Sensor Strip for Analysis of Fentanyl

Abstract

The increasing prevalence of fentanyl and its analogues as contaminating materials in illicit drug products presents a major hazard to first responder and law enforcement communities. Electrochemical techniques have the potential to provide critical information to these personnel via rapid, facile field detection of these materials. Here we demonstrate the use of cyclic square wave voltammetry (CSWV) with screen-printed carbon electrodes (SPCE), modified with the room temperature ionic liquid (RTIL) 1-butyl-1-methylpyrrolidinium bis-(trifluoromethylsulfonyl)imide [C 4 C 1 pyrr][NTf 2 ], toward such rapid "on-the-spot" fentanyl detection. This CSWV-based disposable sensor strip system provides an information-rich electrochemical fingerprint of fentanyl, composed of an initial oxidation event at +0.556 V (vs Ag/ AgCl) and a reversible reduction and oxidation reaction at −0.235 and −0.227 V, respectively. The combined current and potential characteristics of these anodic and cathodic fentanyl peaks, generated using two CSWV cycles, thus lead to a distinct electrochemical signature. This CSWV profile facilitates rapid (1 min) identification of the target opioid at micromolar concentrations in the presence of other cutting agents commonly found in illicit drug formulations. The new protocol thus holds considerable promise for rapid decentralized fentanyl detection at the "point of need".

Self‐Reporting Hydrogel Sensors Based on Surface Instability‐Induced Optical Scattering

“…Water pollution, [ 1,2 ] environmental toxins, [ 3,4 ] hazardous substances, [ 5,6 ] the rise of synthetic recreational drug alternatives like fentanyl, [ 7–9 ] chemical warfare agents, [ 10,11 ] tumor‐specific molecular indicators, insulin levels in diabetics, glucose levels in hypoglycemics, there is certainly no shortage of unique molecules and chemicals that necessitate a quick, sensitive, and in situ method of sensing their presence, especially in aqueous and bodily environments. To date, there exists a multiplicity of methods [ 4,6,12–14 ] capable of sensing significant analytes like those aforementioned and more, be it chromatography, mass spectrometry, electrochemistry, absorption spectroscopy, or IR and Raman spectroscopies, for example.…”

Electrochemical detection of fentanyl using screen-printed carbon electrodes with confirmatory analysis of fentanyl and its analogs in oral fluid using liquid chromatography-tandem mass spectrometry

“…It was shown that norfentanyl did not present any oxidation peak while 4-ANPP demonstrated two oxidative peaks with better peak resolution than fentanyl, confirming the location of the tertiary amine oxidation. 33 We propose that peak I, seen in our work, for the oxidation of fentanyl cannot be due to oxidation of the tertiary amine present as the amide group in fentanyl as this process more likely occurs through hydrolysis in acidic conditions compared with the buffer pH of 8.5 used herein. Furthermore, we do not support the mechanism explained through the oxidation of the tertiary amine for peak I followed by the oxidation of the product secondary amine for peak II.…”

“…73 The authors further demonstrate the analyte adsorption to the electrode through the lone pairs on the nitrogen atoms. 73 Consideration of the papers mentioned above detailing possible mechanisms for the oxidation of amines, oxidation of cinnarizine by Hegde et al, 74 and work demonstrating fentanyl oxidation by Goodchild et al, 33 as well as this work, may aid in the elucidation of the oxidation mechanism of fentanyl. It was shown that norfentanyl did not present any oxidation peak while 4-ANPP demonstrated two oxidative peaks with better peak resolution than fentanyl, confirming the location of the tertiary amine oxidation.…”

“…Further support of both an adsorption and diffusion process is the presence of an oxidation peak in the analysis of 4-ANPP that demonstrates improved peak resolution for peak I and peak II. 33 We suspect that this is due to a higher affinity of 4-ANPP for the electrode surface due to group. Lastly, this process was determined to be an irreversible electron transfer for fentanyl, which was supported through analysis of fentanyl in a drop by successive scans via cyclic voltammetry showing the decrease in peak current and shape with each successive scan ( Figure 27).…”

“…However, the suggestion of peak II arising from the oxidation of the secondary amine of norfentanyl is not supported in the literature, as Goodchild et al demonstrated a complete lack of an oxidation peak. 33 Therefore, both peaks must be due to the N-dealkylation of fentanyl to norfentanyl. As this work demonstrated, peak current increased as the amount of time stirred increased, suggesting that an adsorption process was occurring within the system.…”