Permanganate–bromide–silver nanoparticles as a new chemiluminescence system and its application to captopril determination

A novel chemiluminescence (CL) system based on the oxidation of bromide by permanganate in sulfuric acid medium is introduced. The enhancing effect of silver nanoparticles (NPs), synthesized by chemical reduction method, on this reaction was studied. It was demonstrated that spherical silver nanoparticles with average size of 18 nm had a most remarkable catalytic effect on this reaction. CL emission wavelengths and UV–vis spectra were used to characterize the system and propose a possible mechanism. Furthermore, it was found that captopril inhibits the action of NPs and decreases the intensity of CL. Based on this phenomenon, a new CL method was developed for the determination of captopril in the 3.0×10−10 to 1.0×10−7 mol L−1 concentration range with a detection limit (3 s) of 0.12 nmol L−1. The method was successfully applied to the determination of captopril in pharmaceutical formulations, human urine and serum samples.