Uso do sistema portátil de Análise por Injeção em Batelada (BIA) com detecção eletroquímica para rápidas discriminações entre medicamentos contendo citrato de sildenafila

Abstract

Sildenafil citrate (CS) is the active principle of Viagra® (VI), more selling drug for treatment of erectile dysfunction and one of the counterfeiter drugs in the world. In forensic laboratories or in the literature some methodologies for quality control of VI employ the high-performance liquid chromatography. However, some drawbacks such elevated costs, time consumption and high size of instruments allows the expedition of chemical analyses reports just after the arrest operation. In this work we propose a batch injection analysis (BIA) system and boron-doped diamond working electrode for simple discrimination of pharmaceutical formulations containing sildenafil citrate (reference, generic, counterfeit and adulterated). In this perspective, two strategies were proposed: 1. Voltammetric detection and chemometric classification: Employing hydrodynamic square wave voltammetry (Amplitude: 30 mV; frequency: 30 Hz; dispensing rate: 48 L s-1) with 0.1 mol L-1 sulfuric acid supporting electrolyte was possible to carry out a fast and reproducible screening (RSD = 2,5 %) which acts as a fingerprint of each drug. After a chemometric treatment (method of principal component analysis and hierarchical cluster analysis) the samples were classified in groups. 2. Multiple pulse amperometry (MPA) detection and non-chemometric classification: Each sample was dispensed in the BIA cell by an electronic micropipette (dispensing rate: 100L s-1, injection volume: 200 L) reproducibly (RSD< 3 %, n = 3) while three potential pulses were applied at BDD electrode +1.3 V, 1.6 V + and + 2.1V. The identification of each sample was performed using only the anodic peak currents obtained in each pulse (i+1.3V, i1.6Vand i+2.1V) or ratios among these peak currents (R1 = i+1,6V/i+1,3V, R2 = i+2,1/i+1,6V, R3 = i+2,1V/i+1,3V). Using both strategies 1 or 2 was possible to discriminate between VI (reference and generic) and two counterfeit formulations and VI from five adulterated formulations in the laboratory. However the second strategy, proposed in the first time in literature for discrimination of any sample, is faster and simpler since that the peak current is obtained in a very short time (less than 10 seconds) and the classification does not require any chemometric method. Finally, BIA system proposed is inexpensive, portable and is able to be used in place of the seizure.