Multiwall carbon nanotube-modified electrode as a nanosensor for electrochemical studies and stripping voltammetric determination of an antimalarial drug

A sensitive electrochemical method based on adsorptive stripping differential pulse voltammetry (AdSDPV) developed for the determination of an antimalarial drug, hydroxychloroquine (HCQ), using a multi-walled carbon nanotube (MWCNTs)-modified carbon paste electrode (MWCNTs/CPE). The modified nanosensor due to its enhanced conductivity showed a very large current response from the electroactive substrate. The modified electrode was characterized by different methods such as scanning electron microscopy (SEM) and cyclic voltammetry (CV). Also, some techniques including CV, chronoamperometry (CHA) and chronocoulometry (CHC) were used for electrochemical studies of HCQ. It was observed that by employing MWCNTs/CPE, a 4-fold enhancement in the HCQ signal was observed as compared to the carbon paste electrode (MWCNTs/CPE). Under the optimized conditions, the differential pulse voltammetric peak current was proportional to the HCQ concentration in the range of 5.7 x 10(-8) M to 1 x 10(-4) M with a detection limit (S/N = 3) of 6.0 nM. The analytical applications of the modified sensor were demonstrated by estimating HCQ in pharmaceutical formulations and biological fluids. Also, the modified electrode showed good reproducibility, long-term stability and anti-fouling effects.