Triagem rápida e “in loco” de 3,4-metilenodioxietilanfetamina (MDEA) em drogas empregando eletrodo impresso de carbono e voltametria de onda quadrada

Abstract

All around the world, the production and consumption of synthetic drugs such as New Psychoactive Substances is increasing, in which amphetamine type stimulants (ATS) such as 3,4-methylenedioxyethylamphetamine (MDEA) have been widely seized. Thus, the development of fast and simple analytical methods for the screening of these substances in seized drugs is very important. This work presents an electrochemical method for the screening of MDEA in drugs, using a commercial screen-printed carbon electrode (Dropsens®) and square wave voltammetry (SWV). Initially, the electrochemical behavior was studied by cyclic voltammetry in buffer Britton-Robinson 0.04 mol L-1 at different pHs (2 to 12), in which electrochemical mechanisms have been proposed for the observed processes. However, pH 3 was chosen considering better detectability and a higher number of identifiable peaks (Epa1 = + 0.21 V, Epa2 = + 0.87 V and Epc1 = + 0.15 V). Subsequently, the detection of MDEA was performed by SWV due to the higher sensitivity and sample throughput of the technique. Employing the optimized conditions (amplitude of 40 mV, frequency of 30 Hz and step potential of 4 mV) the following analytical parameters were obtained for peak 1 (Ep1 = 0.16 V) and peak 2 (Ep2 = 0.77 V), respectively: linear range from 5.0 to 50.0 µmol L-1 (R2 > 0.99), sensitivities of 0.217 and 0.144 µA / mol L-1 and limits of detection of 0.07 and 0.11 µmol L-1. The precision of the method was satisfactory, due to the low relative standard deviations (RSD) obtained in successive measurements (P1: RSD <6%; P2 RSD <10%; n = 10). The inter-electrode reproducibility (n = 5) was low in terms of peak current (RSD < 35.4%), but high for peak potentials (RSD < 2.3%). In the interferers study was verified the discrimination of MDEA from common adulterants such as caffeine, paracetamol, glucose and other ATS (amphetamine - A, methamphetamine - MA, 3,4-methylenedioxyamphetamine - MDA), except 3,4-methylenedioxymethamphetamine (MDMA). In addition, MDEA screening was carried out on drugs seized by the Civil Police-DF, and the results compared with those obtained by HPLC-MS. The developed method is fast, simple, pratical, portable and low cost, being promising for applications in forensic chemistry.

All around the world, the production and consumption of synthetic drugs such as New Psychoactive Substances is increasing, in which amphetamine type stimulants (ATS) such as 3,4-methylenedioxyethylamphetamine (MDEA) have been widely seized. Thus, the development of fast and simple analytical methods for the screening of these substances in seized drugs is very important. This work presents an electrochemical method for the screening of MDEA in drugs, using a commercial screen-printed carbon electrode (Dropsens®) and square wave voltammetry (SWV). Initially, the electrochemical behavior was studied by cyclic voltammetry in buffer Britton-Robinson 0.04 mol L-1 at different pHs (2 to 12), in which electrochemical mechanisms have been proposed for the observed processes. However, pH 3 was chosen considering better detectability and a higher number of identifiable peaks (Epa1 = + 0.21 V, Epa2 = + 0.87 V and Epc1 = + 0.15 V). Subsequently, the detection of MDEA was performed by SWV due to the higher sensitivity and sample throughput of the technique. Employing the optimized conditions (amplitude of 40 mV, frequency of 30 Hz and step potential of 4 mV) the following analytical parameters were obtained for peak 1 (Ep1 = 0.16 V) and peak 2 (Ep2 = 0.77 V), respectively: linear range from 5.0 to 50.0 µmol L-1 (R2 > 0.99), sensitivities of 0.217 and 0.144 µA / mol L-1 and limits of detection of 0.07 and 0.11 µmol L-1. The precision of the method was satisfactory, due to the low relative standard deviations (RSD) obtained in successive measurements (P1: RSD <6%; P2 RSD <10%; n = 10). The inter-electrode reproducibility (n = 5) was low in terms of peak current (RSD < 35.4%), but high for peak potentials (RSD < 2.3%). In the interferers study was verified the discrimination of MDEA from common adulterants such as caffeine, paracetamol, glucose and other ATS (amphetamine - A, methamphetamine - MA, 3,4-methylenedioxyamphetamine - MDA), except 3,4-methylenedioxymethamphetamine (MDMA). In addition, MDEA screening was carried out on drugs seized by the Civil Police-DF, and the results compared with those obtained by HPLC-MS. The developed method is fast, simple, pratical, portable and low cost, being promising for applications in forensic chemistry.