Sensitive and selective determination of hydroxychloroquine in the presence of uric acid using a new nanostructure self-assembled monolayer modified electrode: optimization by multivariate data analysis.

A highly sensitive electrochemical nanosensor was developed using covalent modification of a glassy carbon electrode (GCE) by self-assembly of a novel Schiff base. Scanning electron microscopy (SEM) and electrochemical techniques were used to investigate the immobilization of the self-assembled monolayer (SAM) on the GCE. The electrochemical behavior of hydroxychloroquine (HCQ) in the presence of uric acid (UA) at the surface of the modified electrode was studied using the differential pulse voltammetry (DPV) technique. Response surface methodology (RSM) is used to optimize the effects of various operating variables such as pH, immersion time, scan rate, step potential and modulation amplitude on the voltammetric response of HCQ. RSM formulates a mathematical model which correlates the independent parameters with the peak current of HCQ. The central composite rotatable design (CCRD) has been applied to conduct the experiments. Then, under the optimized conditions, HCQ was determined in the presence of UA. The electrochemical measurements demonstrated that this biosensor responded well to HCQ, confirming that the self-assembly immobilization method was effective. Also, the interference, the storage stability, and the reproducibility of the biosensor were studied and assessed. The developed nanosensor was economical and efficient, making it potentially attractive for application to real sample analysis.