Voltammetric, spectrophotometric, and high performance liquid chromatographic analysis of olanzapine

Three novel sensitive, simple, rapid, and precise methods namely voltammetric, spectrophotometric, and high performance liquid chromatographic have been developed for the quantitation of olanzapine in pharmaceutical dosage forms. Voltammetric studies cover three techniques; cyclic voltammetry (CV), differential pulse voltammetry (DPV), and osteryoung square wave voltammetry (OSWV). These techniques were used to investigate the electrooxidation of olanzapine. The data revealed that quantitative determination of this substance could be made by DPV and OSWV in the concentration range of 7.00 x 10(-5) to 1.00 x 10(-3) m. with CV technique the results were not satisfactory for quantitation. In the second method; the first derivative spectrophotometry was used and measurements of first derivative signals at 290.7 nm was taken. Linear calibration graph of first derivative values vs. concentration in the range 2.56 x 10(-5) to 1.24 x 10(-3) M were obtained with negligible intercepts. The third method, is based on high performance liquid chromatography (HPLC) on a reversed-phase column using a mobile phase of phosphate buffer pH: 5.5 and acetonitrile (7:3 v/v). The drug was monitored with a diode-array detector with a fixed wavelength 295.0 run. Liquid chromatography was performed on a RP-YMC pack ODS A-132 C-18 (5 mum, 15 cm x 6.0 mm) column. Linearity range for olanzapine was 1.61 x 10(-6) to 7.24 x 10(-4) M. All the proposed methods were successfully applied to the determination of olanzapine in pharmaceutical dosage forms with high percentage of recovery, good accuracy, and precision without any interference by the excipients.