Peng Yu-Hui, Wu Tsunghsueh, Lin Yang-Wei
Department of Chemistry, National Changhua University of Education, 1 Jin-De Road, Changhua City, 50007, Taiwan.
Department of Chemistry, University of Wisconsin-Platteville, 1 University Plaza, Platteville, WI, 53818-3099, USA.
J Food Drug Anal. 2020 Sep 15;28(3):475-485. doi: 10.38212/2224-6614.1075.
We demonstrated a sensitive electrochemical method for the determination of nonelectroactive melamine (Mel) using a modified glassy carbon electrode (GCE), with uric acid (UA) as the signal reporter. To increase the anodic response of UA, GCE was coated with Au-Ag nanoparticles and a Nafion thin film (Au-Ag/Nafion/GCE). The sensing mechanism was based on the competitive adsorption behavior of Mel on the Au-Ag/Nafion/GCE, which reduces the electroactive surface area of nanoparticles and thus hinders anodic response of UA. Under optimal conditions and the use of an analytical method of differential pulse voltammetry, this modified electrode detected Mel concentrations ranging from 2.5 to 70 nM, with a detection limit of 1.8 nM. The Au-Ag/Nafion/GCE demonstrated satisfactory reproducibility and stability, with relative standard deviations (RSDs) of 9.3% and 7.1%, respectively. The proposed electrochemical method was then successfully used to determine the Mel content in spiked milk powder and cat food samples, with RSDs of 1.7%-9.3% and recoveries of 92.4%-103.7%.
我们展示了一种灵敏的电化学方法，该方法使用修饰玻碳电极（GCE），以尿酸（UA）作为信号报告分子，用于测定非电活性三聚氰胺（Mel）。为了增强UA的阳极响应，GCE表面涂覆了金-银纳米颗粒和一层Nafion薄膜（Au-Ag/Nafion/GCE）。传感机制基于Mel在Au-Ag/Nafion/GCE上的竞争吸附行为，这会减小纳米颗粒的电活性表面积，从而阻碍UA的阳极响应。在最佳条件下并采用差分脉冲伏安法分析，该修饰电极检测到的Mel浓度范围为2.5至70 nM，检测限为1.8 nM。Au-Ag/Nafion/GCE表现出令人满意的重现性和稳定性，相对标准偏差（RSD）分别为9.3%和7.1%。所提出的电化学方法随后成功用于测定加标奶粉和猫粮样品中的Mel含量，RSD为1.7%-9.3%，回收率为92.4%-103.7%。
