Ultraviolet–visible Spectrophotometric and Titration Method for the Assay of Lisinopril Bulk and Pharmaceutical Dosage Form

Abstract

A simple, accurate, fast, and cheap titrimetric assay method and ultraviolet–visible (UV-Vis) spectrophotometric method have been developed for the assay of lisinopril in pharmaceutical pure and tablet dosage form. The method developed in titrimetric method is a color-based indicator method. The assay of lisinopril by UV is based on its absorbance in the UV range. Lisinopril is a long-acting angiotensin-converting enzyme inhibitor. It is used as a first-line drug to manage hypertension, congestive heart failure, and acute myocardial infarction. The titrimetric method is a type of neutralization reaction using methanol as solvent and titrating it against 0.1 N NaOH and 3–4 drops of phenolphthalein as indicator and the appearance of permanent pink color is taken as the endpoint. The average volume of 0.1 N NaOH consumed to neutralize the content in flask was noted and the percent purity of the drug in the tablet formulation was calculated. The analytical methods reported for the determination of lisinopril in tablets are generally based on spectrophotometric measurements. A UV-Vis spectroscopy is an analytical technique that measures the amount of discrete wavelengths of UV or visible light that are absorbed by or transmitted through a sample in comparison to a reference or blank sample. The assay of lisinopril was performed by ethanol and water as diluents and the absorption maxima were at 208 nm. The concentration of the sample was determined by standard calibration curve method. The titrimetric method and UV-Vis spectroscopic method developed are easy, rapid, and simple and can be used as a routine quality control test for both the pure drug and in tablet formulation.