Desenvolvimento e aplicação de eletrodos de grafite de pilhas recicladas para detecção de clonazepam em bebidas alcoólicas

Abstract

The detection and quantification of anxiolytic and hypnotic drugs such as clonazepam (Rivotril®) is of great interest in the forensic area due to its use in alcoholic beverages to facilitate sexual abuse cases. In general, the development of sensitive and accurate analytical methods for the detection of these analytes becomes necessary, taking into account that these drugs are rapidly metabolized and excreted from the body, and that conventional techniques such as immunoassays, mass spectrometry and fluorescence spectroscopy are slow, relatively expensive, consist of more complex sample preparation procedures, and thus require highly skilled analysts. In this context, the present study describes for the first time the fabrication and electrochemical evaluation of a simple and highly sensitive platform for clonazepam (CZP) detection, produced from carbon graphite electrodes (BGE) obtained from discharged AA batteries (1.5V). Therefore, by means of the cyclic voltammetry technique the electrochemical behavior of CZP, the effects of pH and sweep speed on currents and peak potentials were investigated. It was found that the BGE presents high electrocatalytic activity against the reduction of CZP, with an irreversible cathodic peak being observed at -0.57 V attributed to the reduction of the nitro group CZP (NO2) to hydroxylamine (NHOH). Using the differential pulse voltammetry technique, a linear increase in reduction currents was observed as a function of CZP concentration in the range of 6.6 to 78.4 μmol L-1, with high sensitivity (0.19 μA μmol L-1) and detection limit of 0.42 μmol L-1. The proposed electrochemical sensor was then applied to detect CZP in real samples of alcoholic beverages, proving to be highly selective for detection of the drug even when applied in a complex matrix containing a number of other compounds that could be detected as interferents. Therefore, this work provides a promising strategy for the fabrication of reproducible and low-cost electrodes for clonazepam detection in beverages.