Titrimetric determination of catecholamines and related compounds via bromine oxidation and substitution

Abstract

A titrimetric method for the determination of 0.1–10 mg of catecholamines and related compounds as pure substances and in their dosage forms was investigated and found to offer improvements with regard to ease, speed and accuracy. The method is based on bromine oxidation of the catecholamines (adrenaline, noradrenaline, L-dopa, dopamine and methyldopa) to the corresponding benzoquinones; related compounds (octopamine, tyramine and tyrosine) undergo substitution to the dibromoaryl hypobromites. The benzoquinones and hypobromites oxidise iodide to liberate stoicheiometric amounts of iodine, which can be determined titrimetrically with thiosulphate, using starch as an indicator.