Indirect Flow-Injection Determination of Catecholamines with Biamperometric Detection

Abstract A flow-injection (FI) method for the determination of catecholamines (epinephrine, dopamine, and l-dopa) has been developed. The method is based on the indirect biamperometric detection of the drugs by using I3 −/I− as an indicating redox system and flow-through detector with two polarized platinum wire electrodes. Catecholamines are oxidized in the sample loop by potassium permanganate and then the solution containing excess of oxidant is injected to the carrier stream, which merged with acidic solution of potassium iodide. The triiodide formed in reaction coil is detected biamperometrically. The detection limits are: 0.2 µg/mL for dopamine, 0.3 µg/mL for l-dopa, and 0.4 µg/mL for epinephrine. The calibration graphs are linear up to 40 µg/mL of catecholamines. The relative standard deviations are lower than 1.5%. The proposed method has been applied to determine catecholamines in commercially available pharmaceutical formulations.