Prototipagem de células eletroquímicas impressas em 3D miniaturizadas e práticas aplicadas na análise voltamétrica de drogas em amostras forenses e farmacêucas

Abstract

The development of portable electroanalytical devices is of utmost importance for the rapid on-site detection of legal and illegal drugs. In this thesis, novel miniaturized and versatile 3D-printed electrochemical cells were developed for the electroanalysis of drugs in pharmaceutical and forensic samples. In the second chapter, the SMART-EC3D cell (Simple, Miniaturized, Adaptable, Robust, and Transportable) is proposed. Comprising a lid, base, and screw, the cell was fabricated using different 3D printing techniques and materials, with polyethylene terephthalate glycol (PETG) offering the best cost-benefit ratio. The SMART-EC3D demonstrated adaptability with both commercial and low-cost alternative electrodes. Its analytical feasibility was demonstrated through the voltammetric detection and/or determination of seized illicit drugs, including 3,4-methylenedioxy-N-methylamphetamine (MDMA), 2-[4-Iodo-2,5-dimethoxyphenyl]-N-(2-hydroxybenzyl)ethanamine (25I-NBOH), lysergic acid diethylamide (LSD), and pharmaceutical drugs with a history of counterfeiting (tadalafil, sildenafil, and paracetamol). In the third chapter, a miniaturized cell (eSMART-EC3D) was developed and employed with a boron-doped diamond (BDD) electrode to establish a rapid and simple methodology for the screening and determination of the anabolic steroid oxymetholone (OXM) in seized pharmaceutical products and synthetic urine. OXM exhibited an irreversible anodic peak in Britton-Robinson buffer (pH 4), associated with an oxidation mechanism involving the transfer of two electrons and two protons. Subsequently, OXM was detected using square-wave voltammetry, enabling the screening and quantification of OXM in seven seized samples, with results consistent with the official technique (gas chromatography). No interference was observed from five other anabolic steroids. Additionally, OXM recovery values in synthetic urine (89.4 – 110.3%) confirmed the accuracy of the method and its potential for anti-doping testing. The two proposed cells stand out for their robustness, versatility, rapid assembly (~ 30 s), portability, low cost (≈ US$ 1 for eSMART-EC3D and US$ 2 for SMART-EC3D), low sample volume requirement (100 – 1000 µL), and potential application for electroanalysis of solid and liquid samples in the field.