OPTIMIZED AND VALIDATED SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF OLANZAPINE IN PHARMACEUTICAL FORMULATIONS USING 1,2,-NAPHTHOQUINONE-4-SULPHONATE (NQS)

Abstract

Spectrophotometric study was carried out, for the first time, to investigate the reaction between the antipsychotic Olanzapine (OLP) and 1,2-naphthoquinone -4-sulphonate (NQS) reagent. In alkaline medium (pH 13), an orange-colored product exhibiting maximum absorption peak (λmax) at 454nm was produced. The stoichiometry of the reaction was determined and the reaction mechanism was postulated. This color-developing reaction was successfully employed in the development of simple and rapid spectrophotometric method for determination of OLP in its pharmaceutical dosage forms. Under the optimized reaction conditions, Beer’s law correlating the absorbance (A) with OLP concentration (C) was obeyed in the range of 0.4–4 µgml−1. The regression equation for the calibration data was A = 0.0372 + 0.1637C, with good correlation coefficient (0.9997). The molar absorptivity (ε) was 5.6×104 l mol−1 cm−1. The limits of detection, quantification and Sandell sensitivity were 0.09, 0.29 µgml−1 and 0.006 µgcm−2 respectively. The intra-day precision (%RSD) and accuracy (%RE) ranged from 0.2 to 0.67 % and from 0.18 to 0.66 %, respectively, the inter-day (%RSD) and (%RE) values were within 0.12 % and 0.52 %, respectively.The proposed method was successfully applied to the determination of OLP in its pharmaceutical tablets with good accuracy and precisions; the label claim percentage was 100.67± 0.06. The method is practical and valuable for its routine application in quality control laboratories for analysis of OLP.