Fast on-site screening of 3,4-methylenedioxyethylamphetamine (MDEA) in forensic samples using carbon screen-printed electrode and square wave voltammetry

The worldwide seizures of illicit synthetic drugs have been dramatically increasing over the past decade, when the quantity of seized amphetamine-type stimulants (ATS) quadrupled, while seized ecstasy (3,4-methylenedioxymethamphetamine or MDMA)-like substances doubled. In this work, a simple and fast methodology for the electrochemical screening of ecstasy analogue MDEA (3,4methylenedioxyethylamphetamine) in forensic samples is presented, for the first time, using a carbon screen-printed electrode (C-SPE) and square wave voltammetry (SWV). The electrochemical behavior of MDEA was studied by cyclic voltammetry at different pH values (2 to 12), where an altered electrochemistry of this drug on C-SPE, with an unreported redox pair, was observed in comparison with previous works dealing with the voltammetric detection of other ATS with similar chemical structures. Based on the acquired electrochemical processes, a redox reaction mechanism for MDEA on C-SPE is proposed. The best conditions (sensitivity and selectivity) for MDEA screening were obtained by SWV (a: 40 mV, f: 30 Hz, and E-step: 4 mV) and 0.04 mol L-1 Britton Robinson buffer solution at pH 3.0 as the supporting electrolyte. The proposed method presents a wide linear range (2.5 to 30.0 mu mol L-1, R-2 > 0.99), high sensitivity (0.569 mu A / mu mol L-1), low theoretical limit of detection (0.03 mu mol L-1), and good repeatability using the same C-SPE (RSD < 6%; n = 10). The inter-device reproducibility (n = 5) showed a minimal variation of peak potentials (RSD < 2.3%). The interference study was performed with some adulterants usually found in ecstasy tablets, such as paracetamol, caffeine, glucose, ketamine, cocaine, acetylsalicylic acid, amphetamine (A), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), MDMA, ethylone (bk-MDEA), n-ethylpentylone (bk-EBDP) and dibutylone (bk-DMDBD). The method was applied in real seized samples containing MDEA with addition-recovery studies close to 100%. The developed method is promising to be used as a preliminary test for the screening of MDEA in the everchanging situation concerning seized forensic samples. The proposed sensor exhibits attractive features for application in forensic analysis, such as rapidness, simplicity, low-cost, user friendly and portability. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The worldwide seizures of illicit synthetic drugs, particularly amphetamine-type stimulants (ATS) and ecstasy-like substances, have been increasing dramatically over the past decade. This study presents a simple and fast methodology for the electrochemical screening of the ecstasy analogue MDEA in forensic samples using a carbon screen-printed electrode and square wave voltammetry. The proposed method shows promising results with wide linear range, high sensitivity, low theoretical limit of detection, and good repeatability, making it suitable as a preliminary test for screening MDEA in seized forensic samples.