Tarek Wahdan

Electrochemical determination of gatifloxacin, moxifloxacin and sparfloxacin fluoroquinolonic antibiotics on glassy carbon electrode in pharmaceutical formulations.

Three fluoroquinolones; gatifloxacin (GAT), moxifloxacin (MOX) and sparfloxacin (SPAR) were electrochemically studied in various buffer systems at different pH values, using a glassy carbon electrode. The three fluoroquinolones were electrochemically oxidized at potential range (0.65-1.1 V) vs Ag-AgCl-KCl. The oxidation was irreversible and exhibited adsorption-controlled process behavior at all pH values and buffers studied. An electroanalytical methodology based on the adsorptive behavior of fluoroquinolones on glassy carbon electrode (GCE) and according to the linear relation between peak current and concentration using differential pulse voltammetry (DPV) method was successfully applied to the determination of the three fluoroquinolones in bulk and tablets. The proposed methods were statistically in agreement with that obtained by spectrophotometric comparison method.

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.

Voltammetric Determination of Flunixin on Molecularly Imprinted Polypyrrole Modified Glassy Carbon Electrode.

A novel electrochemical sensing approach, based on electropolymerization of a molecularly imprinted polypyrrole (MIPpy) film onto a glassy carbon electrode (GCE) surface, was developed for the detection of flunixin (FXN). The sensing conditions and the performance of the constructed sensor were assessed by cyclic, differential pulse and (DPV) square wave voltammetry (SWV). The sensor exhibited high sensitivity, with linear responses in the range of 5.0 to 50.0 µM with detection limits of 1.5 and 1.0 µM for DPV and SWV, respectively. In addition, the sensor showed high selectivity towards FXN in comparison to other interferents. The sensor was successfully utilized for the direct determination of FXN in buffalo raw milk samples.