Utilization of charge transfer complexation reaction for the spectrophotometric determination of acyclovir as antiviral drug in pharmaceutical formulations

Abstract

The present work aims to develop and validate two simple, sensitive, accurate, precise and economical spectrophotometric methods for the determination of acyclovir (ACV) in pure form and pharmaceutical formulations. The developed methods are based on the formation of charge transfer complex between VAL as n-electron donor and quinalizarin (Quinz) or alizarin red S (ARS) as π-acceptor in methanol to form highly colored chromogens which showed an absorption maximum at 560 and 538 nm using Quinz and ARS, respectively. The optimization of the reaction conditions such as the type of solvent, reagent concentration and reaction time were investigated. Under the optimum conditions, Beer’s law is obeyed in the concentration ranges 1.0–20 and 1.0–24 μg/ml using Quinz and ARS, respectively with good correlation coefficient (r2 ≥ 0.9994) and with a relative standard deviation (RSD% ≤ 0.80). The limits of detection and quantification were found to be 0.30 and 1.0 µg/ml for Quinz and 0.29 and 0.97 µg/mL for ARS. The methods were successfully applied to the determination of VAL in its pharmaceutical formulations and the validity assesses by applying the standard addition technique. Results obtained by the proposed methods for the pure VAL and commercial tablets agreed well with those obtained by the reported method.