Determination of piroxicam in pharmaceutical preparations by continuous-flow chemiluminescence

Abstract

A simple and rapid chemiluminescent method for the assay of piroxicam in pure and in pharmaceutical formulations by flow analysis is proposed. The method is based on the reaction of this drug with N-bromosuccinimide (NBS) in alkaline medium in the presence of fluorescein as sensitizer. The emission intensity is greatly enhanced by the presence of cetyltrimethylammonium bromide (CTAB). The optimum chemical conditions for the chemiluminescence emission were investigated. The calibration graph was linear for the concentration range from 2.0 to 12.0 μg mL⁻¹. The detection limit, according to Clayton et al.(C. A. Clayton, J. W. Hines and P. D. Elkins, Anal. Chem., 1987, 59, 2506), was 0.72 μg mL⁻¹. For analysis of 10 solutions of 8.0 μg mL⁻¹ of this anti-inflammatory, if error propagation theory is assumed, the relative error was less than 1.5%. The present chemiluminescence procedure was applied to the determination of piroxicam in Spanish pharmaceutical formulations, with excellent recoveries, as the determination is free from interference from common excipients.