Using Giemsa Stain for Indirect Spectrophotometric Determination of Olanzapine

Abstract

In this work, an indirect spectrophotometric method for estimation of olanzapine by oxidation and bleaching reaction in its pure and pharmaceutical form has been described. The principle of the method depended on the oxidation of olanzapine in an acidic medium by a known excess of sodium hypochlorite. The residual amount of oxidant (sodium hypochlorite) is consumed in the decolorization of the Giemsa stain. The absorbance of unreacted Giemsa stain at 622 nm is directly proportional to the amount of olanzapine. Beer's law was obeyed over the concentrations from 0.5 to 7.5 μg .ml-1with a good determination coefficient(R2=0.9973). The molar absorptivity was 4.4579x 104 l.mol-1.cm-1and Sandell´s index was 0.007 μg.cm-2. As for RSD% values, they fall within the range 0.56 to 0.69% depending on the concentration level. The values of LOD and LOQ have been assessed and found to be 0.04204 μg. mL-1and 0.1261 μg. mL-1 respectively, while the range of recovery was found to be 99.14% to 100.20%. A standard addition method for the determination of olanzapine was carried out and the results indicated that there are no interferences were observed from common additives found in pharmaceutical preparation(tablets). The recommended method was successfully applied to assay olanzapine in tablets. A t-test has been studied and the results indicated that no significant difference between the t-test results and tabulated values at 95% confidence level.