2-Naphthoquinone-4-sulphonate

Simple, sensitive and specific spectrophotometric method was developed and validated for quantification of nebivolol (NBV) in tablet dosage form. Studies were carried out to investigate the reaction between NBV and 1, 2-naphthoquinone-4-sulphonate (NQS) reagent. In alkaline medium (pH 9), a red-colored product exhibiting maximum absorption peak (λmax) at 521 nm was produced. The stoichiometry of the reaction was investigated and the reaction mechanism was postulated. Under the optimized reaction conditions, Beer's law correlating the absorbance with NBV concentration was obeyed in the range of 2 - 55μg/ml with good correlation coefficient 0.9996. The molar absorptivity was 0.124 × 104l/mol.cm. The limits of detection and quantification were 0.539 and 1.634μg/ml, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2%. No interference was observed from the excipients that are present in the tablets. The proposed method was applied successfully for the determination of NBV in its pharmaceutical tablets with good accuracy and precisions. The results were compared favorably with those of a reference pre-validated method. The method is practical and valuable in terms of its routine application in quality control laboratories.