Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
Food Chem. 2022 May 1;375:131871. doi: 10.1016/j.foodchem.2021.131871. Epub 2021 Dec 16.
An electrochemical sensor for the determination of some polyphenolic compounds such as Gallic acid (GA) and Galloyl esters was developed using the activated pencil lead electrode (APLE). At first, a study has been made of the optimum conditions for electrochemical activation of the pencil lead electrode. Potentiodynamic and potentiostatic strategies were investigated for activation of the pencil lead electrode and the results show that the potentiodynamic pretreatment gives better performance toward measurement of the polyphenolic compounds. Electrochemical properties of GA were investigated using chronoamperometry and cyclic voltammetry; and some thermodynamic and kinetic variables such as α, n , and D were calculated. Sensitive differential pulse voltammetry (DPV) technique was applied for the determination of Gallic acid and Galloyl esters in different samples. Enhanced oxidation peak currents of Gallic acid were observed at APLE when compared with non-activated PLE. The calibration graph has two linear ranges of 0.49-24.3 µM and 0.07-0.83 mM, and the obtained limit of detection for S/N = 3 was 0.25 µM. Adsorptive stripping differential pulse voltammetry (AdSDPV) was also conducted to determine Gallic acid and Galloyl esters in sub-micromolar concentration range. Using the AdSDPV method, the limit of detection was improved and calculated to be 5.2 nM. The proposed method was successfully applied for quantification of the total concentration of Gallic acid and Galloyl esters in a variety of real samples such as black and green tea, and mango juice samples, and desirable recovery values indicated the good accuracy of the developed sensor.
一种电化学传感器，用于测定某些多酚化合物，如没食子酸（GA）和没食子酰酯，使用活性铅笔芯电极（APLE）开发。首先，研究了铅笔芯电极电化学活化的最佳条件。研究了动电位和恒电位策略对铅笔芯电极的活化作用，结果表明，动电位预处理对测量多酚化合物的性能更好。使用计时安培法和循环伏安法研究了 GA 的电化学性质；并计算了一些热力学和动力学变量，如α、n 和 D。灵敏的差分脉冲伏安法（DPV）技术用于不同样品中没食子酸和没食子酰酯的测定。与非活化 PLE 相比，APLE 观察到没食子酸的增强氧化峰电流。校准曲线有两个线性范围，分别为 0.49-24.3 µM 和 0.07-0.83 mM，信噪比为 3 时得到的检测限为 0.25 µM。还进行了吸附剥离差分脉冲伏安法（AdSDPV）以测定亚微摩尔浓度范围内的没食子酸和没食子酰酯。使用 AdSDPV 方法，提高了检测限，并计算为 5.2 nM。该方法成功应用于多种实际样品（如黑茶、绿茶和芒果汁）中没食子酸和没食子酰酯总浓度的定量，并得到了令人满意的回收率值，表明所开发传感器具有良好的准确性。
