CHEMILUMINESCENCE ANALYSIS OF CAPTOPRIL - COMPARISON BETWEEN LUMINOL AND RHODAMINE B-SENSITIZED CERIUM(IV) METHODS

Two chemiluminescence methods for the determination of captopril are c ompared in the present paper. The first method is based on the reactio n of captopril with the luminol-hydrogen peroxide-copper(II) system, t he copper(II) ion acting as a key species in the light-emitting proces s. The catalytic activity of copper(II) decreases due to complex forma tion with the sulphhydrylic captopril analyte. Application of this ind irect method allows captopril determinations in the 8.0-1.0 mu M range as starting concentrations. Similarly, captopril was capable of gener ating chemiluminescence from acid cerium(IV) solutions, a reaction tha t could be analytically exploited by the inclusion of the rhodamine B fluorophore yielding a sensitized-type of chemiluminescence emission t hat allowed quantitation of captopril concentrations in the 0.1-6.0 mu M range with a detection limit of 0.037 mu M (original concentration) . For both types of reaction the experimental conditions were optimize d and a direct application was carried out on a commercial drug formul ation.