聚L-天冬氨酸/多壁碳纳米管修饰电极法快速测定麦麸中的酚酸

Preparation of Poly-L-Aspartic acid/MWCNTs Modified Electrode for Fast Determination of Phenolic Acid in Wheat Bran

研究了电聚合法结合吸附法制备聚￡一天冬氨酸／多壁碳纳米管修饰电极及其对酚酸类物质的电化学催化作用及机理，建立了一种快速测定小麦麸皮中酚酸的新方法。在pH3．0的磷酸氢二钠一柠檬酸溶液组成的电解质溶液中，该纳米修饰电极对没食子酸氧化有显著的电催化作用，没食子酸在电极上的氧化动力学过程为吸附控制过程；没食子酸在该纳米修饰电极上的氧化电流与其浓度在2×10^-65．6×10^-5mol／L范围具有良好的线性关系，最低检测限为7．6×10^-7mol／L。利用该法测定了小麦麸皮中酚酸含量，其结果为（1130．8±4．50）μg／g，与Folin—Cioealteu比色法的测定结果（1180．7±8．18）μg／g一致，且具有简便、快速、灵敏的优点，所需化学试剂较少。

The poly - L - Asp/MWCNTs modified electrodes have been prepared combined with electro - poly- merization and absorption method. The vohammetry behavior of gallic acid on the poly - L - Asp/MWCNTs modified electrode has been studied. A new method to determine phenolic acid in wheat bran by differential pulse vohammetry was established. In disodium hydrogen phosphate and citric acid buffer solution （ pH 3.0） , the modified electrode showed a strong electrocatalytic activity on the oxidation of gallic acid ; the electrode reaction of gallic acid was an ad- sorption control process. On optimized conditions, the calibration curves of determination of gallic acid in foods showed an excellent linear response in range 2 ×10^-6 - 5. 6 ×10^-5 mol/L with detection limit of 7.6 ×10^-7 mol/L. The developed method was successfully applied in the determination of total phenolic acid in wheat bran; the results of （1 130.8 ±4.50 ） μg/g were well consistent with the national standard method as Folin -Ciocaheu colorimetric method （ 1 180.7± 8.18） μg/g. It is feasible to use poly -L - Asp/MWCNTs modified electrodes for fast determina- tion of phenolic acid in food with less requirement of chemical reagent.