Copper(II)-neocuproine reagent for spectrophotometric determination of captopril in pure form and pharmaceutical formulations

A simple, rapid, sensitive and accurate spectrophotometric method for the determination of captopril in pure form and pharmaceutical formulations is developed. The procedure is based on the reaction of copper(II) with captopril in the presence of neocuproine (NC) (2,9-dimethy1-1,10-phenanthroline) reagent in acetate buffer at pH 5.0. Copper(II) is reduced easily by captopril to Cu(1) neocuproine complex, which shows an absorption maximum at 448 nm. Beer's law was obeyed in the concentration range 0.3-3.0 mu g mL(-1) with a minimum detection limit (LOD) of 0.039 mu g mL(-1) and a quantification limit (LOQ) of 0.129 mu g mL(-1). For more accurate results, Ring-bom optimum concentration ranges was 0.5-2.7 mu g mL(-1). The apparent molar absorbtivity and Sandell sensitivity were calculated. The validity of the proposed method was tested by analyzing the pure and pharmaceutical formulations and compared well with those obtained by the official method and demonstrated good accuracy and precision. (C) 2010 King Saud University. All rights reserved.