Detection of ascorbic acid by a nickel-manganese oxide composite electrochemical sensor
Nickel manganese oxide composite(Mn-Ni-Oxide),prepared by one-step hydrothermal method and characterized by XRD,SEM,EDS and FTIR,was used to modify glassy carbon electrode by drop-coating method to construct an electrochemical sensor for rapid detection of ascorbic acid.The electrochemical behavior of ascorbic acid on the Mn-Ni-Oxide modified electrode was analyzed by cyclic voltammetry(CV)and differential pulse voltammetry(DPV).The results showed that the outer surface of Mn-Ni-Oxide was a porous nanosphere with the main components of Mn2O3 and NiMnO3.When the acetic acid/sodium acetate buffer solution was at pH=4 and the modification amount of Mn-Ni-Oxide for the modified electrode was 10 μL,the concentration(c)of ascorbic acid was linearly related to the value of oxidation peak current(Ip)in the range of 0.1～9000 μmol/L,with the linear equation of Ip=3.2435c+17.198(R2=0.9920),the detection limit of 0.025 μmol/L,and the sensitivity of 3.2435 μA·m·L/(mol·cm).When applied to the determination of ascorbic acid in fruit juice,the sensor showed recoveries of spiked standards ranging from 95.5％to 103.1％,demonstrating its good prospects for application in food analysis.
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