Stability Indicating High Performance Liquid Chromatographic Method for the Assay of Diltiazem Hydrochloride in Tablets

A rapid high performance liquid chromatographic (HPLC) method for the determination of diltiazem hydrochloride, a calcium antagonist, is described. The stability indicating nature of the method was demonstrated by resolving diltiazem from products of decomposition. Reverse phase liquid chromatography was performed with an octadecyl silane-bonded silica column at ambient temperature, using UV detection at 240 nm. The mobile phase consisting of acetonitrile, methanol and 0.05 M monobasic potassium phosphate (25:20:55) was pumped at 2 ml/min. The internal standard was cyproheptadine hydrochloride. A percent RSD of > 1.5% and correlation coefficient 0.9996 were achieved over the concentration range studied (10-50 μg/ml.)