State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036, People's Republic of China.
School of Tea &Food Science and Technology, Anhui Agricultural University, Hefei, 230036, People's Republic of China.
Mikrochim Acta. 2019 Nov 22;186(12):835. doi: 10.1007/s00604-019-3936-1.
A dual (colorimetric and fluorometric) method is described for sensitive and selective determination of the herbicide glyphosate. It is based on the use of a system composed of polyethylenimine-capped NaGdF:Yb,Er upconversion nanoparticles (UCNPs), copper(II) ions, hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine. The physicochemical and photophysical properties of the polyethylenimine-capped UCNPs were characterized by various spectroscopic and microscopic techniques. The fluorescence of the UCNPs (with main emission peaks at 548 and 660 nm under 980 nm excitation) is reduced in the presence of Cu(II) because of the formation of a blue oxidation product of 3,3',5,5'-tetramethylbenzidine as a result of the peroxidase mimicking activity of Cu(II). In the presence of glyphosate, its strong affinity for Cu(II) leads to the formation of N-(phosphonomethyl)glycine copper(II) complexes. This inhibits the quenching ability and catalysis activity of Cu(II). Hence, fluorescence is increasingly less reduced. Fluorescence at 660 nm increases linearly in the 0.05 to 125 μg·mL glyphosate concentration range and the detection limit is found 9.8 ng·mL. The colorimetric assay (performed at 652 nm) has a detection ranges from 5 to 125 μg·mL, and the limit of detection is 1 μg·mL. Graphical abstractSchematic representation of UCNP-HO-TMB-Cu(II) mixed system for optical determinations of glyphosate.
一种双（比色和荧光）方法用于灵敏和选择性测定除草剂草甘膦。它基于使用由聚乙烯亚胺封端的 NaGdF:Yb,Er 上转换纳米粒子 (UCNP)、铜 (II) 离子、过氧化氢和 3,3',5,5'-四甲基联苯胺组成的系统。聚乙烯亚胺封端的 UCNP 的物理化学和光物理性质通过各种光谱和显微镜技术进行了表征。在存在 Cu(II) 的情况下，UCNP 的荧光（在 980nm 激发下具有 548nm 和 660nm 的主要发射峰）会降低，因为 3,3',5,5'-四甲基联苯胺的蓝色氧化产物的形成是由于 Cu(II) 的过氧化物酶模拟活性。在草甘膦存在下，其与 Cu(II) 的强亲和力导致形成 N-(膦酸甲基)甘氨酸铜 (II) 配合物。这抑制了 Cu(II) 的猝灭能力和催化活性。因此，荧光的减少程度越来越小。在 0.05 至 125μg·mL 草甘膦浓度范围内，660nm 处的荧光呈线性增加，检测限为 9.8ng·mL。比色测定（在 652nm 下进行）的检测范围为 5 至 125μg·mL，检测限为 1μg·mL。摘要图 用于光学测定草甘膦的 UCNP-HO-TMB-Cu(II) 混合系统的示意图。
