Abstract
Two novel 96-microwell-based spectrophotometric assays have been developed and validated for determination of irbesartan (IRB) in its tablets. The two methods were based on the formation of colored charge. transfer (CT) complexes between IRB as a n-electron donor and each of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and p-chloranilic acid (pCA) as pi-electron acceptors. The proposed assays were carried out in 96-microwell plates, and the absorbances were measured by microwell. plate reader. Under the established optimum conditions, Beer`s law was obeyed in IRB concentration ranges of 1-160 and 0.5-180 mu g/ml, for DDQ and pCA methods, respectively. No interference was observed from the additives that are present in the tablets or from hydrochlorothiazide that is co-formulated with IRB in some tablets. The assays were successfully applied to the determination of IRB in tablets with good accuracy and precision. The two assays have high throughput properties, consume minimum volumes of organic solvents thus reduce the exposures of the analysts to their toxic effects, and they reduce the analysis cost by 50-fold. Although the proposed assays were validated for IRB, however, the same methodology could be used for any electron-donating analyte for which a CT reaction can be performed.