RP-HPLC estimation

A simple, accurate and stability indicating high performance liquid chromatographic (HPLC) method was developed for the simultaneous estimation of Torsemide and Spironolactone in combined dosage form. Isocratic RP-HPLC separation was achieved on Kromasil RP- C18 column (250mm×4.6mm; 5µm) using methanol: acetonitrile: water in the ratio of 50:30:20 (v/v), pH6.8, at flow rate of1.0ml/min at ambient temperature. Quantization was achieved by UV detection at 235nm over the concentration range of 10-60μg/ml for torsemide and 25-150μg/ml for spironolactone with percentage recoveries of range 99.688-101.792 and 98.282-101.811for torsemide and spironolactone respectively. Different stress degradation studies like acidic, alkaline, peroxide, thermal etc were measured for both standard drugs and results found that the stress degradation conditions doesn’t affect the elution of the both the drugs and hence the developed method was found to be stability indicating method.

A simple, precise, rapid and accurate reverse phase high performance liquid chromatography method (RP-HPLC) in isocratic mode has been developed for the estimation of ranolazine in pure form and in its tablet dosage form. An Agilent Eclipse XDB C18, 150 x 4.6 mm, 5mm particle size column, with mobile phase consisting of phosphate buffer pH 3.5 and acetonitrile in the ratio of 65:35 % v/v was used. The flow rate was 1.0 mL/min and the column effluent was monitored at 272 nm. The retention time was 4.7 min. The detector response was linear for ranolazine in the concentration range of 10-150 µg/mL. The limit of detection (LOD) was found to be 0.034 μg/mL. The limit of quantification (LOQ) was 0.102 μg/mL. The method was validated by determining its accuracy, precision and system suitability. The results of the study showed that the proposed RP-HPLC method is simple, rapid, precise and accurate, which is useful for the routine determination of ranolazine in pure drug and in its tablet dosage form.