Developing and Analytical Application of Modified Electrode for the Electrochemical Determination of RFX Veterinary Drug

Rafoxanide (RFX) drug substance, belongs to the salicylanilide group of anthelmintic drugs. In this work, Electrochemical behaviour and analytical applications of RFX were investigated by the cyclic voltammetry (CV), adsorptive stripping square-wave voltammetry (AdSSWV), and adsorptive stripping differential pulse voltammetry (AdSDPV) on modified titanium dioxide/multi-walled carbon paste electrode (TiO₂/MWCNTPE). The RFX showed a well-defined anodic signal, and has an irreversible electrode reaction, at approximately 0.45 V in the optimum pH 6.0 Britton Robinson (BR) buffer solutions. Some parameters of stripping modules such as supporting electrolyte, pH, frequency, deposition time, pulse time and pulse amplitude, etc. were optimized to develop the most sensitive electroanalytical method. Furthermore, the calibration graphs were created using the standard addition technique with AdSSWV and AdSDPV on the optimum condition. It has a linear working range of 2.0–16.0 mg/L with AdSSWV and 2.5–14 mg/L with AdSDPV for the determination of RFX in pH 6.0 BR buffer solution on the TiO₂/MWCNTPE. The limit of determination (LOD) by AdSSWV and AdSDPV, which are the most important validation parameter, was found to be 0.054 and 0.072 mg/L, respectively. To investigate the selectivity of the method, analysis of 5 mg/L RFX was carried out on TiO₂/MWCNTPE with AdSSWV in the presence of various heavy metals and some organic substances. The interference agents had no significant effect on the determination of RFX (less than 10% within the tolerance range). Finally, the RFX drug was successfully evaluated in tap water samples by the proposed AdSSWV without any pretreatment with a high percent recovery. This study for RFX determination has been improved to deduce, a fast, inexpensive, reliable, portable, environmentally friendly, selective, and sensitive new electroanalytical method in real samples.