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抗坏血酸(AH_2)在玻碳和铂电极上的过电位较大,其电极反应不可逆.有关AH_2在碳及其它修饰电极上的电催化氧化已有一些报道,如减压热处理、Al_2O_3微粒研磨、普鲁士蓝修饰膜和聚乙烯二茂铁修饰膜等.本文研究了铁氰化镍修饰膜电极催化AH_2氧化的电化学行为.发现其阳极峰电流与AH_2浓度呈线性关系,可测定1×10~(-7)mol/L的AH_2,其灵敏度比聚乙烯二茂铁修饰电极提高一个数量级.用于蔬菜、水果中AH_2的测定,结果满意.
Ascorbic acid (AH_2) has a large overpotential on glassy carbon and platinum electrodes, and its electrode reaction is irreversible. There are some reports about the electrocatalytic oxidation of AH_2 on carbon and other modified electrodes, such as vacuum heat treatment, Al 2 O 3 particle grinding, Prussian Blue modified film and polyethylene ferrocene modified film etc. The electrochemical behavior of AH 2 oxidation catalyzed by nickel ferricyanide was studied in this paper.It was found that there was a linear relationship between the anodic peak current and the concentration of AH 2 and the determination of 1 × 10 ~ -7) mol / L, the sensitivity of AH_2 was improved by one order of magnitude compared with that of polyethylene ferrocene modified electrode.It was used for the determination of AH_2 in vegetables and fruits with satisfactory results.