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 μM and detection limit for Xt was 3.0 nM and of course we obtained good dynamic range between 0.1 to 300 μM and good limit of detection 0.05 μM 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.