Determinação de epinefrina em fármaco por análise de injeção em batelada (BIA) e análise por injeção em fluxo (FIA) com detecção eletroquímica

Abstract

This master's thesis presents the development and validation of an electrochemical method aiming its use for the electrochemical determination (amperometry) of epinephrine (EP) in a drug using batch injection analysis (BIA) or flow injection analysis (FIA) systems. The electrochemical analyzes were performed using a cathodically pretreated boron-doped diamond (BDD) electrode as working electrode. The electrochemical characterization of EP under a BDD electrode showed an analyte oxidation peak with higher electrochemical signal at pH 7.0 using 0.01 mol L-1 phosphate buffer electrolyte. The best conditions obtained in the electrochemical determination of EP using the BIA system were: injection rate of 70 μL s-1, injection volume of 100 μL and application of a potential 0.85 V × Ag/AgCl (sat. KCl). The limits of detection (LOD) and quantification (LOQ) obtained by the BIA method with amperometric detection were 0.05 μmol L-1 and 0.1 μmol L-1, respectively. The relative standard deviation (RSD) of 10 successive analyzes at the same EP concentration was 1.37%, showing excellent repeatability. For the FIA system with amperometric detection, the best conditions for the investigated parameters were obtained at 200 μL for injection volume and 3.0 mL min-1 for injection speed, with an applied potential of 0.85 V × Ag/AgCl (sat. KCl ). The LOD and LOQ obtained for the electrochemical determination of EP performed in the FIA system were 1.0 μmol L-1 and 4.0 μmol L-1, respectively, with a RSD of 4.45% (n = 10). The average recoveries in the application of both methods (FIA and BIA) for electrochemical determination of EP in pharmaceutical formulation (ampoules) ranged between 113% and 119%, with the accuracy lower than 20%, which demonstrates the good accuracy and precision of the developed methods.