Application of oxidative coupling reactions for the estimation of ritodrine hydrochloride in bulk sample and dosage forms

Three simple and sensitive visible spectrophotometric methods (M1, M2 and M3) have been described for the estimation of ritodrine hydrochloride (RTH) in pure state and in unit dosage forms. These are based on the oxidative coupling reaction of RTH, with 3-methyl benzothiazolione hydrazone (MBTH) in the presence of cerium 1V (Ce IV) (Method M1), N,N-dimethylamino-paraphenylenediamine (DMPD) in the presence of chloramine-T (CAT) (Method M2) and 4-aminophenazone (4-AP) in the presence of [Fe(CN6)]3− (Method M3). The variable parameters in all these methods have been optimised and the chemical reactions involved are presented. The results obtained in the three methods are statistically validated and recoveries range from 99.7 to 101.3%.