Sensor eletroquímico baseado em folhas de grafite com tratamento de plasma frio para a detecção de atropina em bebidas.

Abstract

Atropine, an alkaloid extracted from the Atropa belladonna plant, is widely recognized for its pharmacological properties and is used in the treatment of several medical conditions. However, atropine is also frequently used as a drug of abuse, especially in situations of sexual violence. This work presents the development of an electrochemical sensor for the detection of atropine in beverage samples, using graphite sheets as the working electrode. The graphite sheets were subjected to cold plasma treatments of CO₂ and O₂ to evaluate the effect on the sensitivity and efficiency of the sensor. The use of plasma treatment proved to be effective in increasing sensitivity, with the sheet treated with CO₂ showing the best performance in sensitivity and the lowest limit of detection (LOD = 3.0 μmol L⁻¹) in relation to those treated with O₂ and untreated, 3.1 and 4.1 μmol L⁻¹, respectively. The impact of pH on atropine activity was evaluated, and it was determined that pH 11 provided the best electrochemical performance. The differential pulse voltammetry (DPV) technique was chosen due to its high sensitivity and detection capacity at low atropine concentrations. Intra- and inter-electrode precision tests demonstrated good reproducibility, with relative standard deviations of 8.91% and 3.8%, respectively. The tests indicated that the optimized sensor presented detection and quantification limits suitable for the identification of atropine at concentrations below the toxic level, with recoveries above 97% in cachaça samples. Interference studies showed that compounds such as ascorbic acid, glucose and benzodiazepines did not compromise the selectivity of the method. It is concluded that the developed sensor represents a practical, low- cost and portable alternative, with possible field application for rapid and reliable analyses.