A simple, rapid and sensitive method has been developed for the analysis of fexofenadine (FEX) in pharmaceutical formulations, using a tris(1,10-phenanthroline)-ruthenium(II) [Ru(phen)(3)(2+)] peroxydisulphate chemiluminescence (CL) system in a multichip device. Various parameters that influence the CL signal intensity were optimized. These included pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve in the range 0.05-5.0 µg/mL was obtained. The detection limit was found to be 0.001 µg/mL. The procedure was applied to the analysis of FEX in pharmaceutical products and was found to be free from interference from concomitants usually present in these preparations.

A new method for the analysis of mebeverine hydrochloride (MEB) has been developed using a two-chip device. The method is highly selective, sensitive, rapid and consumes minute amount of reagents. The developed method is free of interference from the degradation products of MEB and from common ingredients present in pharmaceutical formulations. The limit of detection was 0.043 µg/mL, and the limit of quantification was 0.138 µg/mL. The short analysis time per sample (20 s) allowed a large number of analyses to be performed within a very short time. Various samples were analyzed, including two different pharmaceutical formulations and a uniformity of content analysis for 20 tablets from a known batch and two biological samples at different concentrations. In addition, the method was compared with a validated high-performance liquid chromatography (HPLC) method and the results clearly indicated the suitability of the developed method for routine analyses. A new mechanism for the tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3 (2+) )-peroxodisulfate (S2 O8 (2-) ) chemiluminescence (CL) system has also been proposed. The mechanism is based on photoinduced oxidation of Ru(bpy)3 (2+) to Ru(bpy)3 (3+) via the formation of Ru(bpy)3 (2+) * upon irradiation with visible light. S2 O8 (2-) then oxidizes Ru(bpy)3 (2+) * to Ru(bpy)3 (3+) and the analyte subsequently reduces the resultant Ru(bpy)3 (3+) to Ru(bpy)3 (2+) *, which then produces the CL signal.