Determination of propylthiouracil in pharmaceutical formulation by high-performance liquid-chromatography with a post-column iodine-azide reaction as a detection system.

A high-performance liquid chromatographic method with a post-column iodine-azide reaction has been chosen and tested for validity in quantitative determination of propylthiouracil in tablets. A mobile phase with a flow rate of 1.4 ml/min was conducted in the form of isocratic chromatography on a C18 column with acetonitrile-water-sodium azide solution (2.5%; pH 5.5) 24:26:50 (v/v/v). Unreacted iodine from post-column iodine-azide induced by reaction was monitored with visible detection at lambda=350 nm. The method proved both its linearity within the range of 8-100 nM (r2>0.9988) and satisfactory results of inter-day precision (RSD<4.2%) and accuracy (recovery>91%). The limits of detection (DDL) and quantification (DQL) reached the levels of 5 and 8 nM, respectively. The validation of the method comprised also its specificity. The results obtained proved the suitability and appropriateness of the suggested method for intended use.