DETERMINATION OF DIHYDROCHLORIDES OF DRUGS BY LINEAR TITRATION METHOD

A linear graphic method for the determination of the equivalence points of dihydrochlorides of drugs is presented in order to replace the traditional non-aqueous titration in pharmaceutical analysis. The titration is carried out potentiometrically. Equal volumes of the titrant are added stepwisely. The detection of end points of the titration by means of linear regression analysis is also recommended. The titration data can be treated by a programmable pocket calculator such as TI-59, and more satisfactory results are obtained than those when the salts are simply treated as a monohydrochloride. It is discussed further-more that the result from the method represents the part having the physiological activity of the drug, not the part of the hydrochloric acid redical.