Voltammetric behaviour of rabeprazole at a glassy carbon electrode and its determination in tablet dosage form.

The oxidative behaviour of rabeprazole was studied at a glassy carbon electrode in Britton-Robinson (BR) buffer solutions using cyclic, linear sweep and differential-pulse voltammetry. The oxidation process was shown to be irreversible over the pH range (6.0-11.0) and was diffusion-adsorption controlled. An analytical method was developed for the determination of rabeprazole in BR buffer solution at pH 8.0 as supporting electrolyte. The anodic peak current varied linearly with rabeprazole concentration in the range 1.0 x 10(-6) to 2.0 x 10(-5) M of rabeprazole with a limit of detection of 4.0 x 10(-7) M. Validation parameters, such as sensitivity, accuracy, precision and recovery, were evaluated. The proposed method was applied to the determination of rabeprazole in the tablet dosage form. The results were compared with those obtained by a published high-performance liquid chromatographic method. No difference was found statistically.

Determination of cefonicid in human urine by adsorptive square-wave stripping voltammetry.

The adsorption behavior of cefonicid on the hanging mercury drop electrode (HMDE) has been examined using cyclic voltammetry and square-wave voltammetry techniques in Britton-Robinson (B-R) buffers in the pH range of 2.0-11.0. The effect of different parameters on the accumulation behavior of the adsorbed species has been evaluated. Sensitive measurements can be achieved after controlled adsorption on the surface of HMDE followed by square-wave voltammetry. Under optimal conditions, a detection limit of 4.0 x 10(-8) M and a linear calibration graph in the range 1.0 x 10(-7)-1.0 x 10(-6) M were obtained. Direct simple determination of cefonicid in urine was established with no manipulation of urine sample other than dilution and subsequent adsorptive stripping voltammetric determination. The detection limit of the method was 1.0 microg x ml(-1) of cefonicid in urine.