Electrocatalytic determination of captopril using voltammetry methods at the nano zeolite modified carbon paste electrode

Captopril (CAP) is an orally active inhibitor of the angiotensin converting enzyme and is generally used for the treatment of hypertensive illness alone or in combination with other drugs [1]. This compound can also be used to treat congestive heart failure [2]. several in vitro studies indicate that captoprilfunctions as an antioxidant both by rising the activities of antioxidant enzymes for example superoxide dismutase and glutathione peroxidase and by scavenging reactive oxygen species (ROS) [3]. Numerous methods have been applied to the determination of CAP, such as chromatography, spectrophotometry, fluorimetry, spectrophotometry, electrophoresis and electrochemical methods [1-4]. There are several limitations for electrochemical determination of pharmaceutical compounds, such as slow electron transfers kinetics, low sensitivity and reproducibility and high overpotentials. The chemical modifications with electroactive materials couse considerable advantages in the design and development of electrochemical sensors. Through the electrochemical reaction, the mediator transfers electrons between the analyte and the electrode with considerable decrease in the activation overpotential [5, 6]. The present work deals with zeolite-modified electrode doped with Fe ions for captopril oxidation. The performance of Fe–zeolite-modified carbon paste electrode towards captopril oxidation compared with unmodified carbon paste electrode using cyclic voltammetric and Chronoamperometry techniques. Cyclic voltammetry techniques proved to be very helpful in this concern. To prepare the modified ZSM-5 zeolite with Ni ions, a propreate of synthesized nano zeolite was immersed to 10 ml of 1M NiCl2 solution for 3 h. Then, the ion exchanged zeolite was dried in oven at 347 K for 8 h. A mixture of 0.015g of nanosized NiZSM-5, 0.35g of graphite powder and paraffin was blended to prepare the zeolite modified carbon paste [NZMCP]. The resulting paste was then inserted in a glass tube. The electrical conection was implemented by a copper wire lead fitted into the glass tube. The carbone paste electrode (CPE), used for comparison, was prepared in the same way but omitting the zeolite addition 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 46 step. The oxidation of captoprile was studied at CPE and NiZSM-5/CPE by cyclic voltametric experiment in NiOH solution. Then the obtained results were compared with each other. The electrochemical behavior of modified carbon paste electrodes in the forms of NiZSM-5CPE and unmodified carbon paste electrode were studied using of cyclic voltammetric techniques. The obtained results show that the modified carbon paste electrode NiZSM-5CPE is the suitable electrode for electrooxidation of captoprile fig 1. Also using of cyclic voltammetric techniques the linear dynamic range and detection limits for captoprile were calculated 2*10-6 - 3* 10-4 and 0.384mM respectively.