Electrochemical Behavior and Voltammetric Determination of Two Synthetic Aroyl Amides Opioids

Abstract

In the present work, we describe the electrochemical behaviour of two opioids structurally related to aroyl amides of forensic interest, namely U-47700 and AH-7921. The data obtained allowed for the mise-au-point of a voltammetric determination protocol, that relies on differential pulse voltammetry (DPV) at a glassy carbon electrode in ethanol/0.1 M lithium perchlorate/0.10 M 2,6-lutidine. To apply the method to the analysis of real samples (urines), a clean-up and a preconcentration strategy by solid phase extraction (SPE) using the adsorbent Florisil have been developed. LOQ of 0.2 μg·mL−1 in urine samples with an enrichment factor of 20 and linear range from 5 to 150 μg·mL−1 were obtained.

A Screen-Printed Voltammetric Sensor Modified with Electropolymerized Molecularly Imprinted Polymer (eMIP) to Determine Gallic Acid in Non-Alcoholic and Alcoholic Beverages

“…Gallic acid’s electrochemical oxidation was characterized using cyclic voltammetry and exhaustive coulometry [ 48 , 49 , 50 ]. In particular, the number of electrons involved in the entire electrochemical process was determined using exhaustive coulometry [ 48 , 49 , 50 ] by electrolyzing gallic acid at a potential slightly above (from 50 to 100 mV) the oxidation peak in a three-electrode cell under a gentle flow of nitrogen. A Pt gauze was employed as a working electrode, a Pt wire was the counter electrode, and Ag/AgCl/3 M KCl was the reference electrode.…”

“…A rough estimate of the formal potential ( E 0′ ) for an irreversible process was obtained from the intercept of the plot anodic peak potential ( E p , V) vs. scan rate ( v , V/s) [ 49 , 52 ].…”

“…In the present study, after preliminary measurements using the mixture of K 4 Fe(CN) 6 /K 3 Fe(CN) 6 followed by measurements of K 3 Fe(CN) 6 alone, similar results were obtained, so all the subsequent experiments were performed with the last probe. Gallic acid's electrochemical oxidation was characterized using cyclic voltammetry and exhaustive coulometry [48][49][50]. In particular, the number of electrons involved in the entire electrochemical process was determined using exhaustive coulometry [48][49][50] by electrolyzing gallic acid at a potential slightly above (from 50 to 100 mV) the oxidation peak in a three-electrode cell under a gentle flow of nitrogen.…”