New Two-fold Amplified Electroanalytical Sensor for Determination of Xanthine in the Presences of Caffeine in Food Samples

Fast and sensitive response electrochemical sensor based on CoFe2O4 nanoparticle and 1-buthyl-3-methyl imidazolium bromide room temperature ionic liquids carbon paste electrode (CoFe2O4/NP/ILs/CPE) is fabricated for the determination of Xanthine (Xt) in the presences of Caffeine in fish and fruit samples. In the first step, CoFe2O4/NP was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and results showed synthesized nanoparticle with diameter between 26.92-29.22 nm. The electro-oxidation of Xt and Caffeine occurred at a potential about 0.7 V and 1.1 V, which was much better in comparison with bare carbon paste electrode in phosphate buffer (pH=6.0) at the surface of the (CoFe2O4/NP/ILs/CPE). Other electrochemical techniques were also investigated including cyclic voltammetry, differential pulse voltammetry (DPV) and chronoamperometry at CoFe2O4/NP/ILs/CPE. At optimized conditions for Xt and Caffeine analysis, DPV peak currents showed a wide linear dynamic ranging from 8.0 nM to 500 mu M and detection limit for Xt was 3.0 nM and of course we obtained good dynamic range between 0.1 to 300 mu M and good limit of detection 0.05 mu M for caffeine. As a result, the proposed electrode could determine Xt in the presences of Caffeine in real samples with good selectivity and high sensitivity.