Indirect kinetic method for the quantitative determination of catecholamines in pharmaceuticals

Abstract

An indirect kinetic method is proposed for the determination of adrenaline and noradrenaline. The method is based on the iodination of these compounds in a buffered solution (pH 5.5) where the resulting iodide subsequently acts as catalyst in the reaction between cerium(IV) and arsenic(III). The system is monitored spectrophotometrically at 375 nm (absorption maximum of the cerium (IV) ion) and the measured initial rate is proportional to the amount of catecholamine present in the sample. The determination ranges are 5–25 μg of adrenaline and 3–30 μg of noradrenaline, and the precision (RSD) is of about ±2%. The proposed method has been satisfactorily applied to the determination of these catecholamines in several pharmaceutical preparations.