Burcu Dogan

Anodic voltammetric behavior and determination of cefixime in pharmaceutical dosage forms and biological fluids.

The voltammetric behavior of cefixime was studied using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. The oxidation of cefixime was irreversible and exhibited diffusion controlled process depending on pH. The oxidation mechanism was proposed and discussed. Different parameters were tested to optimize the conditions for the determination of cefixime. The dependence of current intensities and potentials on pH, concentration, scan rate, nature of the buffer was investigated. According to the linear relationship between the peak current and the concentration, differential pulse (DPV) and square wave (SWV) voltammetric methods for cefixime assay in pharmaceutical dosage forms and biological fluids were developed. For the determination of cefixime were proposed in acetate buffer at pH 4.5, which allows quantitation over the 6 x 10(-6)-2 x 10(-4)M range in supporting electrolyte and spiked serum sample; 8 x 10(-6)-2 x 10(-4)M range in urine sample; 6 x 10(-6)-1 x 10(-4)M range in breast milk samples for both techniques. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and in the biological samples, respectively.

Anodic Voltammetric Behavior and Determination of Antihistaminic Agent: Fexofenadine HCl

Abstract A voltammetric study of the oxidation of fexofenadine HCl (FEXO) has been carried out at the glassy carbon electrode. The electrochemical oxidation of FEXO was investigated by cyclic, linear sweep, differential pulse (DPV), and square wave (SWV) voltammetry using glassy carbon electrode. The oxidation of FEXO was irreversible and exhibited diffusion‐controlled process depending on pH. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. Different parameters were tested to optimize the conditions for the determination of FEXO. For analytical purposes, a very well resolved diffusion‐controlled voltammetric peak was obtained in Britton‐Robinson buffer at pH 7.0 with 20% constant amount of methanol for DPV and SWV techniques. The linear response was obtained in supporting electrolyte in the ranges of 1.0×10−6–2.0×10−4 M with a detection limit of 6.6×10−9 M and 5.76×10−8 M and in serum samples in the ranges of 2.0×10−6–1.0×10−4 M with a detection limit of 8.08×10−8 M and 4.97×10−8 M for differential pulse and square wave voltammetric techniques, respectively. Only square wave voltammetric technique can be applied to the urine samples, and the linearity was obtained in the ranges of 2.0×10−6–1.0×10−4 M with a detection limit of 2.00×10−7 M. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of FEXO in dosage forms and biological fluids. For the precision and accuracy of the developed methods, recovery studies were used. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from the endogenous substances and additives present in tablets.

Electrochemical Characterization of Flupenthixol and Rapid Determination of the Drug in Human Serum and Pharmaceuticals by Voltammetry

Abstract Flupenthixol hydrochloride (FLP) has an antipsychotic activity against depression and is irreversible oxidizable at the glassy carbon electrode in various buffer systems and at different pH values. The mechanism of the oxidation process was discussed. According to the linear relation between the peak current and FLP concentration, differential pulse and square wave voltammetric methods for its determination in pharmaceutical dosage forms and spiked human serum samples were developed. For analytical purposes, a very well resolved diffusion controlled voltammetric peak was obtained in Britton‐Robinson buffer at pH 7.02 (20% methanol) at 0.75 and 0.79 V for differential pulse and square wave voltammetric techniques, respectively. The linear response was obtained in the ranges of 8 × 10−7 to 1 × 10−4 M with a detection limit of 1.17 × 10−7 M for differential pulse and 1 × 10−6 to 1 × 10−4 M with a detection limit of 2.86 × 10−7 M for square wave voltammetric techniques. The repeatability and reproducibility of the methods for both media (supporting electrolyte and serum sample) were determined. Precision and accuracy of the developed method were used for the recovery studies. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from the endogenous substances and additives present in tablets. The authors thank Lundbeck Pharm. Ind. for providing pure flupenthixol and commercial tablets for developing proposed method. This research was realized by using BAS 100W equipments, which were supplied from the grant from Ankara University Scientific Research Project Foundation (Grant No. 20030803037 and Grant No. 20030803043), Turkey.