Han En, Zhang Maoni, Pan Yingying, Cai Jianrong
School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China.
Materials (Basel). 2022 Apr 11;15(8):2809. doi: 10.3390/ma15082809.
The accurate determination of nitrite in food samples is of great significance for ensuring people's health and safety. Herein, a rapid and low-cost detection method was developed for highly sensitive and selective detection of nitrite based on a surface-enhanced Raman scattering (SERS) sensor combined with electrochemical technology and diazo reaction. In this work, a gold nanoparticle (AuNP)/indium tin oxide (ITO) chip as a superior SERS substrate was obtained by electrochemical self-assembled AuNPs on ITO with the advantages of good uniformity, high reproducibility, and long-time stability. The azo compounds generated from the diazotization-coupling reaction between nitrite, 4-aminothiophenol (4-ATP), and N-(1-naphthyl) ethylenediamine dihydrochloride (NED) in acid condition were further assembled on the surface of AuNP/ITO. The detection of nitrite was realized using a portable Raman spectrometer based on the significant SERS enhancement of azo compounds assembled on the AuNP/ITO chip. Many experimental conditions were optimized such as the time of electrochemical self-assembly and the concentration of HAuCl. Under the optimal conditions, the designed SERS sensor could detect nitride in a large linear range from 1.0 × 10 to 1.0 × 10 mol L with a low limit of detection of 0.33 μmol L. Additionally, nitrite in real samples was further analyzed with a recovery of 95.1-109.7%. Therefore, the proposed SERS method has shown potential application in the detection of nitrite in complex food samples.
准确测定食品样品中的亚硝酸盐对于保障人们的健康与安全具有重要意义。在此，基于表面增强拉曼散射（SERS）传感器结合电化学技术和重氮反应，开发了一种快速且低成本的检测方法，用于高灵敏度和高选择性地检测亚硝酸盐。在这项工作中，通过在氧化铟锡（ITO）上电化学自组装金纳米颗粒（AuNP）获得了一种优异的SERS基底——AuNP/ITO芯片，其具有良好的均匀性、高重现性和长期稳定性。亚硝酸盐、4-氨基硫酚（4-ATP）和盐酸萘乙二胺（NED）在酸性条件下重氮化偶联反应生成的偶氮化合物进一步组装在AuNP/ITO表面。基于组装在AuNP/ITO芯片上的偶氮化合物显著的SERS增强效应，使用便携式拉曼光谱仪实现了亚硝酸盐的检测。对许多实验条件进行了优化，如电化学自组装时间和氯金酸（HAuCl）浓度。在最佳条件下，所设计的SERS传感器能够在1.0×10至1.0×10 mol/L的大线性范围内检测亚硝酸盐，检测限低至0.33 μmol/L。此外，对实际样品中的亚硝酸盐进行了进一步分析，回收率为95.1 - 109.7%。因此，所提出的SERS方法在复杂食品样品中亚硝酸盐的检测方面显示出潜在的应用价值。
