Titrimetric assay of isoniazid with perchloric acid in non-aqueous medium

A rapid, simple, cost-effective, accurate and precise direct titrmetric method for the determination of isoniazid (INH) in pharmaceutical preparations has been developed and validated. The method is based on the titration of INH with 0.02 M acetous perchloric acid in glacial acetic acid using crystal violet as indicator. The method is applicable over the range of 1.5–15.0 mg INH. The validation of the method yielded good results that included precision (RSD < 3% for intra- and inter-day precision), and accuracy (relative error ≤2.6%). It was also found that the excipients in the commercial tablet preparation did not interfere with the assay and the results were comparable with the official method.