Batch-Injection Amperometric Determination of Sulfamethazine, Sulfacetamide, and Sulfathiazole on an Electrode Modified with a Composite of Gold Nanoparticles, Carbon Nanotubes, and an Ionic Liquid

Electrodes modified with gold particles, multi-walled carbon nanotubes, an ionic liquid based on 1-butyl-3-methylimidazolium hexafluorophosphate, and a composite derived from these materials have been developed for the voltammetric determination of sulfamethazine, sulfacetamide, and sulfathiazole. Cyclic voltammetry reveals that modifying the surface of a glassy carbon electrode with gold particles, a composite of carbon nanotubes, and an ionic liquid increases its effective surface area. Electrochemical impedance data indicate that the rate of electron transfer on the modified electrodes surpasses that on the unmodified ones. The composite electrode containing gold particles, carbon nanotubes, and the ionic liquid, exhibited the best performance, was utilized for the amperometric determination of sulfonamides in a batch-injection analysis system. Optimal parameters for the determination of sulfonamides in the batch-injection setup were found. The relationship between the analytical signal and the concentration of the compounds on the logarithmic coordinates is linear, ranging from 1 x 10(-8) to 5 x 10(-3) M for sulfamethazine and sulfacetamide, and from 1 x 10(-7) to 5 x 10(-3) M for sulfathiazole. The proposed method for determining sulfonamides has been tested in ananalysis of pharmaceutical preparations.