Application of experimental design for quantification and voltammetric studies of sulfapyridine based on a nanostructure electrochemical sensor

In the present paper, differential pulse voltammetry (DPV) coupled with experimental design, as a new method, was developed for determination of sulfapyridine (SP). These measurements were carried out in a 0.2M Britton–Robinson (B–R) buffer solution at the surface of multi-walled carbon nanotubes modified carbon paste electrode (MWCNT/CPE). Operating conditions were improved with central composite rotatable design (CCRD), involving several chemical and instrumental parameters such as pH, MWCNT amount, scan rate, step potential and modulation amplitude. DPV, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were applied for characterizing of the modified electrode. The modified electrode showed enhanced effect on the oxidation peak current of SP. The electron transfer coefficient (α=0.77), exchanging current density (j0=1.82×10−11Acm−2) and diffusion coefficient (D=2.03×10−5cm2s−1) of SP were calculated by linear sweep voltammetry (LSV) and chronoamperometry methods, respectively. Some analytical parameters such as repeatability, linear dynamic range (5.96–161.07M) and detection limit (DL) (49.55nM) for SP were also obtained. Finally, the proposed method was successfully applied for determination of SP in plasma samples.