Design and fabrication of modified carbon paste electrode based on cobalt- graphite carbon nitride for the determination of naproxen

Naproxen is considered one of the most important non-steroidal anti-inflammatory drugs, which is used to treat many diseases, including seizures, congestive heart and kidney failure, stomach ulcers,and is used to prevent increased bleeding after an injury. Other common side effects include gastrointestinal diseases including bloating, indigestion, nausea, and vomiting [۱,۲]. Different procedures have been developed for the determination of naproxen. They include capillary electrophoresis [۳], spectrophotometric [۴] and fluorometric determination, spectrofluorometry,liquid chromatography [۵], and electrochemical techniques. Among these methods, electrochemical techniques have received a lot of attention, as they are simple, economical, and precise. In this study,the electrochemical behavior of the naproxen drug was evaluated by modifying the carbon paste electrode based on cobalt-graphite carbon nitride. Cobalt-graphite carbon nitride was synthesized and characterized by scanning electron microscopy (SEM) and X- ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FT-IR). Afterward, a modified carbon paste electrode based on cobalt-graphite carbon nitride was fabricated and the electrochemical behavior of naproxen sensor was evaluated using cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). Important parameters such as pH, the amount of the modifier, buffer, and accumulation time were investigated and optimized. The calibration curve showed that the electrode has two linear ranges of ۰.۰۱ to ۰.۰۸ mmol/L and ۰.۱ to ۰.۸ mmol/L and the detection limit is ۰.۰۰۱۱۷ mmol/L. The electrode has very good reproducibility (RSD=۵.۷%) and reproducibility (RSD=۳.۳%). The designed electrode was used to measure naproxen in human serum samples. The results showed that the electrode has a very good ability to measure naproxen in biological samples.