Spectrophotometric Determination of Quinidine with Tetrabromophenolphthalein Ethyl Ester

Abstract

A spectrophotometric method is proposed for the quantitative determination of quinidine. The method is based on solvent extraction of quinidine and tetrabromophenol-phthalein ethyl ester together into dichloroethane. Quinidine was found to form an addition-compound with the reagent in the organic solvent. Quinidine is determined by measuring the absorbancy of the extracts within the concentration range from 1.6×10^-6 to 8.0×10^-6M. The effect of diverse substances and the composition of the colored species were also investigated.