Sensitive Spectrophotometric Method for the Determination of Olanzapine and Orphenadrine in Pure and Dosage Forms by Ternary Complex Formation with Eosin and Lead(II)
The present paper describes a simple and sensitive spectrophotometric method for the determination of olanzapine (OLZ) and orphenadrine (ORP) in pure and in dosage forms. The developed method is based on ternary complex formation of drugs under investigation with eosin and lead(II) using methyl cellulose as surfactant. The formed ternary complex which shows maximum absorbance (λmax) at 540 nm for both drugs OLZ and ORP, respectively. The optimum experimental conditions for the ternary complex formation were established. The Beer’s law is obeyed in the concentration ranges, 0.0-35.0 and 0.0-55 μg/mL for both methods. The molar absorptivity values for methods A and B were found to be 1.03 × 104 and 0.51 × 104 L mol-1 cm-1, respectively with the corresponding Sandell’s sensitivity values 0.0303 and 0.0602 μg cm-2. The proposed methods were further applied to the determination of OLZ and ORP in bulk and in pharmaceutical preparations via standard addition technique. No interference was observed from the common adjuvants added to the tablets which are applicable for the assay of the investigated drugs in different dosage forms.