NiO nanoparticles modified carbon paste electrode as a novel sulfasalazine sensor.

The sol-gel synthesized NiO nanoparticles were characterized and used for the modification of a carbon paste electrode (CPE) in electrocatalytic voltammetric determination of sulfasalazine. Calcination temperature of NiO had an important role on the peak current of the modified NiO-CPE and calcined NiO at 200 °C had the best and maximum peak current for the corresponding electrode. Jahn-Teller and a Z-out effects for the singlet electrons in their 3dz2 orbital for calcined NiO at 200 °C relatively instable such electrons and hence they can easily participate in the electro-oxidation process. The electrochemical impedance spectroscopy (EIS) results confirmed that the modified CPE by calcined NiO at 200 °C has lower charge transfer resistance. In interaction effects study between the experimental variables by using the response surface methodology (RSM) approach, the optimized run included the 17.5% of NiO modifier, 0.5 M NaOH, amplitude of 295 mV, step potential of 7 mV and frequency of 15 Hz. A calibration plot in the range of 0.009-1.6 μM with limits of detection (LOD) and quantification (LOQ) of 0.002 and 0.006 μM was obtained, respectively. The modified electrode showed good selectivity and applicability for SSZ determination in complex matrixes.