Aplicação de folhas de grafite tratadas com plasma de CO2 na detecção eletroquímica de midazolam

Abstract

Benzodiazepines (BZD) stand out among the psychoactive substances most associated with crimes and are often classified as Crime Facilitating Drugs (CFDs). Midazolam (MID), in particular, has high solubility in aqueous solutions due to the presence of an imidazole ring in its chemical structure, which increases its basicity and favors the formation of water-soluble salts. In this context, the determination of MID in beverages has proven to be an important alternative in criminal investigations. This work describes a simple, effective, and low-cost method for the selective determination of MID in alcoholic beverages. Differential pulse voltammetry, using graphite sheets treated with CO₂ plasma (GPT) in acetate buffer (pH 4), was employed as the electrochemical technique, with the working electrode and supporting electrolyte used, respectively. The following differential pulse parameters were optimized: modulation amplitude of 80 mV, potential increment of -5 mV, and modulation time of 20 ms. Different linear response ranges for two MID peaks were found: (peak 1: 1.0–10.0 µmol L⁻¹ and r = 0.993 (range 1); 10.0–50.0 µmol L⁻¹ and r = 0.986 (range 2); peak 2: 2.5–15.0 µmol L⁻¹ and r = 0.998 (range 1); 15.0–50.0 µmol L⁻¹ and r = 0.959 (range 2)). The detection limits obtained for the two peaks, 1 and 2, were 0.204 and 0.094 mol L⁻¹, respectively.