Contributions to Drug AnalysisXXI. Determination of Methylrosanilinium Chloride Content by Differential Titration ofVarious Functional Groups in Protogenic Non-Aqueous Medium

Overview

Differential titration of various functional groups in the drug molecule (N + Cl - and amino groups) isproposed to solve the problem of the determination of methylrosanilinium chloride content in thesubstance according to PhBs 4 (the results are higher than the theoretical possibility) by titrating0.1 M HClO4 in acetic acid with potentiometric indication (glass and saturated calomel electrodes)1/1 (as N + Cl - ). A mixture of 35 ml of chloroform with 15 ml of acetic acid anhydride was proposedand tested as a suitable medium for this titration; the weighed-out amount is about 0.1100 g,titration in the surroundings of end points after 0.30 ml of volumetric solution. The result of thedetermination is calculated from the differences of consumptions of the volumetric solutions fortitrations of various functional groups (1 ml corresponds to 0.02040 g of the drug). Precision of thedetermination by this procedure is characterised by estimation of a standard deviation about 1.5%and the results are in a substantially better agreement with expectations.

Key words:
methylrosanilinium chloride – content determination – acidimetry – non-aqueousmedium – differential titration