A simple and accurate method is suggested for the determination of 5,7-diiodoquinolin-8-ol and 5-chloro-7-iodoquinolin-8-ol in a pure state as well as in various pharmaceutical preparations. The liberation of the iodine content of the compounds investigated is based on simple refluxing with 15 per cent. sodium hydroxide solution in the presence of zinc metal powder. Interference in the subsequent steps of the determination, due to the resulting organic products, is overcome by precipitation and filtration of these products prior to titration.

The suggested method is applicable to the determination of the compounds under investigation in a convenient concentration range that is suitable for the determination of different dosage forms without numerous dilutions. Any unnecessary dilutions may result in high experimental error.