Electrochemical behaviour and voltammetric determination of sulphadiazine using a multi-walled carbon nanotube composite film-glassy carbon electrode

The anodic oxidation of sulphadiazine (SD) was investigated at a glassy carbon electrode modified by multi-walled carbon nanotube (MWCNT-GCE), using cyclic voltammetry and chronoamperometry. The results indicate that MWCNT-modified GCEs show an efficient and selective electrocatalytic activity towards the anodic oxidation of SD among biologically important compounds in buffered solutions at pH=7. It was found that oxidation of SD at the surface of MWCNT-GCE occurs at a potential less positive than that of unmodified GCE (about 100mV). The diffusion coefficient of SD was also estimated using chronoamperometry. The kinetic parameters such as the electron transfer coefficient between SD and modified electrode, , and the charge transfer rate constant, k(s) , for oxidation of SD at the MWCNT-GCE surface were determined according to the Laviron procedure. The dissociation constants of oxidised and reduced acid-base species of SD can be obtained from the E-1/2 versus pH curves. The linear dependence of the peak current on the concentration was observed in the range 10-2000 mu molL(-1) with a detection limit of 7.1 mu molL(-1). The method was also applied to determinate the SD in human blood plasma and urine samples.