STOPPED-FLOW CHEMILUMINESCENCE SPECTROMETRY TO IMPROVE THE DETERMINATION OF PENICILLINS BASED ON THE LUMINOL IODINE REACTION

The light generated in the reaction between luminol and iodine was used for the indirect stopped-flow chemiluminescence spectrometric determination of penicillins based in their inhibitory effect on this reaction. The reaction was monitored via direct rate measurements on the formation and decay steps of the chemiluminescence process in addition to peak-height measurements that were made for comparison. The proposed method allows the determination of penicillins in the range 1 x 10(-6) - 1.2 x 10(-4) M with a relative standard deviation of ca. 2% and a sampling frequency of 120 h-1. The method is relatively free from the interference of common excipients accompanying penicillins in pharmaceutical samples. Its figures of merit (precision, rapidity, sample consumption and liability to automation) compare favourably with those of its batch counterpart, which entails a chemiluminescence titration assay.