Fabrication of an Economic Electrochemical Sensor Based on Cobalt Oxide Nanoparticles for Determination of Flufenamic Acid

An electrochemical sensor for anti-inflammatory drug flufenamic acid, based on cobalt oxide (Co 3 O 4 ) modified carbon paste electrode (CPE), has been fabricated. Co 3 O 4 NPs was synthesized and characterized by UV-visible spectrophotometry, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The novel 0.5%(w/w)Co 3 O 4 /CPE sensor was also evauatedusing the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It showed a much-enhanced electroactive surface area and low charge transfer resistance ( R ct ), revealing that it has greatly enhance electron transfer process. Square wave voltammetry (SWV) was utilized as a sensitive method for the determination of very low concentrations of flufenamic acid. Under the optimized conditions, the limits of detection (LOD) and quantification (LOQ) of 0.5%Co 3 O 4 (w/w)/CPE were 4.8×10 –9 M (1.35 ng/mL) and 1.6×10 –8 M (4.50 ng/mL), respectively. After validation of the fabricated sensor, it was successfully applied for sensitive and selective determination of the drug in spiked human serum with LOD and LOQ of 4.5×10 –8 M (12.65 ng/mL) and 1.5×10 –7 M (42.18 ng/mL).