Spectrophotometric determination of gliclazide in pharmaceuticals and biological fluids through ternary complex formation with eosin and palladium (II)

A simple and sensitive spectrophotometric method has been developed for the determination of gliclazide (GLZ) in pharmaceutical formulations and biological fluids. The proposed method is based upon the formation of a ternary complex between palladium (II), eosin and GLZ in the presence of methyl cellulose as a surfactant and acetate buffer of pH 4.5. The ternary complex showed an absorption maximum at 550 nm. The solution of ternary complex obeyed Beer's law over the concentration range of 0.5-4 microg ml(-1) with minimum detectability (S/N = 2) of 0.05 microg ml(-1) (1.545 x 10(-7) M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets. The results obtained were in good agreement with those obtained using the official or reference spectrophotometric method. The proposed method was further applied to spiked human urine and plasma, the percentage recoveries were 97.84 +/- 0.72 and 97.43 +/- 0.83, respectively, (n = 4). A proposal of the reaction pathway was presented.