Potentiometric Determination of Captopril in Pharmaceutical Formulations

Captopril, chemically know as 1-[(2S)-3mercapto-2-methylpropionyl]-L-proline, (CPT) is used therapeutically as an antihypertensive agent [11, 15], which is also prescribed for the treatment of congestive hart failure [6]. Several types of analytical procedures have been proposed for the analysis of captopril in pharmaceuticals formulations. These procedures include capillary electrophoresis [13], high-performance liquid chromatography (HPLC) [3, 4, 5, 9], polarography [10], voltammetry [23], coulometry [20], amperometry [18], conductometry [19], fluorimetry [12] , colorimetry [1, 2, 7, 14, 22, 24] and flow injection methods.[12, 21, 28]. Some of theses procedures are not simple for routine analysis and required expensive or sophisticated instruments. Potentiometric methods with ion-selective membranes electrodes (ISE’s) can provide valuable and straightforward means of assaying captopril in pharmaceutical formulations because of the possibility to determine directly the active ions in the solution. ISEs’ low-cost, easy of use and maintenance, and the simplicity and speed of assay procedure, and the reliability of the analytical information make them very attractive for the assay of pharmaceutical products. Potentiometric methods based in the reactivity of thiol group have been used for captopril determination in pharmaceutical formulations [8, Abstract