Validated Spectrophotometric Methods for Determination of Selegiline HCl as an Irreversible Inhibitor of Monoamine Oxidase in Pure Form and Pharmaceutical Formulations

Abstract

Sensitive, simple, precise, reproducible, and validated spectrophotometric methods have been developed for the determination of an irreversible inhibitor of monoamine oxidase (selegiline hydrochloride) in pure form and pharmaceutical formulations. The methods are based on the formation of a yellow-colored ion-pair complex between selegiline hydrochloride and three acid dyes, namely, bromocresol green (BCG), bromothymol blue (BTB), bromophenol blue (BPB), and bromocresol purple (BCP), in an acidic buffer solution with absorption maxima at 420, 415, 414, and 410 nm, respectively. Several parameters, such as pH, buffer type and volume, reagent volume, sequence of addition, and effect of extracting solvent, were optimised. Under the optimum experimental conditions, Beer’s law is obeyed over the concentration ranges of 1.0–14, 1.0–12, 1.0–10, and 1.0–16 μg/ml for BCG, BTB, BPB, and BCP, respectively, with good correlation coefficients (0.9992-0.9998). The apparent molar absorptivity's and Sandell’s sensitivity values are reported for all methods. The limit of detection (LOD) and the limit of quantification (LOQ) values are found to be 0.27, 0.3, 0.29, and 0.3 μg/ml and 0.90, 1.0, 0.97, and 1.0 μg/ml for BCG, BTB, BPB, and BCP, respectively. The stoichiometric ratio of the formed ion-pair complexes was found to be 1:1 (drug:reagent) for all methods, as deduced by Job's method of continuous variation. The proposed methods were successfully applied for the determination of selegiline hydrochloride in pharmaceutical formulations with good accuracy and precision. A statistical comparison of the results was performed using the Student's t-test and variance ratio F-test at the 95% confidence level, and there was no significant difference between the reported and proposed methods regarding accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition techniques in accordance with ICH guidelines.