Towards Developing a Screening Strategy for Ecstasy: Revealing the Electrochemical Profile

Abstract

This article describes the development of an electrochemical screening strategy for 3,4‐methylenedioxymethamphetamine (MDMA), the regular psychoactive compound in ecstasy (XTC) pills. We have investigated the specific electrochemical profile of MDMA and its electro‐oxidation mechanisms at disposable graphite screen‐printed electrodes. We have proved that the formation of a radical cation and subsequent reactions are indeed responsible for the electrode surface passivation, as evidenced by using electron paramagnetic resonance spectroscopy and electrochemistry. Thereafter, pure cutting agents and MDMA as well as simulated binary mixtures of compounds with MDMA were subjected to square wave voltammetry at pH 7 to understand the characteristic electrochemical profile. An additional measurement at pH 12 was able to resolve false positives and negatives occurring at pH 7. Finally, validation of the screening strategy was done by measuring a set of ecstasy street samples. Overall, our proposed electrochemical screening strategy has been demonstrated for the rapid, sensitive, and selective detection of MDMA, resolving most of the false positives and negatives given by the traditional Marquis color tests, thus exhibiting remarkable promises for the on‐site screening of MDMA.

Electrochemical methods for on-site multidrug detection at festivals

“…1), the measuring conditions (buffer, pH, electrode material) are selected in such a way that the drug yields a clear EP that can be successfully distinguished from other electroactive compounds present in real samples. The optimization of measuring conditions has previously been reported for the detection of cocaine, 34,42,43 MDMA [35][36][37] and ketamine. 44,45 In particular, the use of pH12 buffer on unmodified carbon SPEs is highly suitable for the detection of these three illicit drugs in the presence of their adulterants.…”

“…44,45 In particular, the use of pH12 buffer on unmodified carbon SPEs is highly suitable for the detection of these three illicit drugs in the presence of their adulterants. 33,37,40 Meanwhile, the detection of amphetamine is complicated by the high oxidation potentials of primary amines, 46 which fall outside the accessible potential window (>1.5 V) in an aqueous environment on unmodified graphite screen-printed electrodes.…”

“…Carbon-based screen-printed electrodes (SPEs) in particular are perfect candidates for the on-site analysis of suspicious samples: they are highly portable, cheap and disposable. 29 Utilizing the characteristic EP for identification on SPEs (unmodified or including a short pre-treatment step or coating), previous studies have reported accurate detection strategies for numerous drugs in the presence of adulterants, including cocaine, 33,34 MDMA, [35][36][37] heroin 38,39 and ketamine. 40 However, these studies generally focus on the detection of one drug, while LEAs at music festivals and other nightlife settings require screening tools for a variety of drugs.…”

Voltammetric Responses of a CYP2D6‐Based Biosensor to 3,4‐methylenedioxymethamphetamine (MDMA) and the Synthetic Cathinone α‐pyrrolidinopentiophenone (α‐PVP).

“…Electrochemistry is a novel and reasonable alternative for detecting psychoactive substances, [14–16] as its advantages include high sensitivity, selectivity towards electroactive species, a wide linear range, portable and low‐cost instrumentation, speciation capability, and a wide range of electrodes that allow performing assays in unusual environments [17,18] . Moreover, electrochemical techniques can achieve extremely low detection limits, in the nanomolar range, [19] comparable to those obtained with chromatographic procedures [20,21] with very small sample volumes (5–0 μL), [19] which is critical in complex environments such as forensics, where evidence can be found in very small quantities.…”

“…[6][7][8][9] Current information about the toxicology of synthetic cathinones is limited, making it a wide field to explore partly due to the great structural variety that characterizes the group of synthetic cathinones; [10] however, CYP2D6 is known to be involved in the metabolism of α-pyrrolidinopentiophenone (α-PVP). Taking as a starting point the findings of studies based on the detection of metabolites resulting from the biotransformation of α-PVP in urine samples of consumers [11] and in vitro studies, [12] it is known that CYP2D6 is the only isoenzyme involved in the formation of the metabolites OH-α-PVP and 2'-OH-α-PVP [12] and that these two metabolites are mainly found in the urine of α-PVP consumers, with OH-α-PVP being more abundant [11,13] Electrochemistry is a novel and reasonable alternative for detecting psychoactive substances, [14][15][16] as its advantages include high sensitivity, selectivity towards electroactive species, a wide linear range, portable and low-cost instrumentation, speciation capability, and a wide range of electrodes that allow performing assays in unusual environments. [17,18] More-over, electrochemical techniques can achieve extremely low detection limits, in the nanomolar range, [19] comparable to those obtained with chromatographic procedures [20,21] with very small sample volumes (5-0 μL), [19] which is critical in complex environments such as forensics, where evidence can be found in very small quantities.…”