Spectrophotometric methods for estimation of amlodipine besylate in pure form and in it’s pharmaceutical formulations

Abstract

Two unexpensive, sensitive, reproducible UV- spectrophotometric methods were developed for the determination of Amlodipine Besylate (ADB) in pure form and in pharmaceutical dosage forms. The first method was using Crystal violet dye (CV) as reagent (Tris (4-dimethyl amino) phenyl) methylium chloride). This method relied on oxidizing (ADB) in acidic medium in presence of an oxidizing agent of potassium bromide: potassium bromate (KBr:KBrO₃) to form a blue colored product of absorbance at λ_max 592 nm, It obeys the Beer's law in a concentrations range of (5-92.5) µg/ml with a molar absorptivity (2.13×10⁵) L/mole.cm and the limit of detection is (0.01) µg/ml. The second method includes the reduction reagent p-nitroaniline using a nitrogenous agent (NaNO₂) in an acidic medium followed coupling reaction between (ADB) and p-nitroaniline to form yallow product has absorbance at λ_max 368 nm, It obeys the Beer's law in a concentrations range of (10-200) µg/ml with a molar absorptivity (3.42×10⁵) L/mole.cm and the limit of quantification is found to be (0.01) µg/ml.  The tow proposed methods are successfully applied for measuring the quantity of (ADB) in pure form and in tablets formulations.