determine methylene blue based on carbon paste electrode modified with nanoparticles of nickel oxide-nitrogen carbon quantum dots and carbon structures by cyclic voltammetry

This paper deals with an electrochemical method for the determination of methylene blue (mb) by fabrication of an electrode based on a carbon paste modified with nano-nickel oxide and nitrogen carbon quantum dots (nio-ncqd), graphene-carbon nitride (g-c3n4), reduced graphene oxide (rgo), and graphite powder and paraffin oil are as a plasticizer. this electrode is used as a working electrode.  the analytical method used is cyclic voltammetry (cv), the oxidation-reduction curve of methylene blue was shown using this electrode. it is a quasi-reversible curve, and it works at (ph =1) and the best acid used is hcl a concentration of (0.1m). it was also found that the linear range is within the range of (7.99-31.98 mg l-1). the standard deviation (sd) and relative standard deviation (rsd%) were obtained at (0.361 mg l-1 and 0.294 mg l-1) and (4.52% and 3.68%) for both oxidation and reduction respectively. retrospective, the limit of quantitative (loq) and limit of detection (lod) were achieved at (99.65%; 99.70%), (0.24 mg l-1; 0.13 mg l-1), and (0.071 mg l-1; 0.039 mg l-1) for both oxidation and reduction respectively. methylene blue was analyzed by uv-vis spectrophotometry at (663 nm).