绿茶提取液制备金纳米粒子及其在VC比色分析中的应用

Green Synthesis of Gold Nanoparticles Using Green Tea Extract and Their Application for Colorimetric Analysis of Vitamin C

以绿茶提取液为还原剂和保护剂,简单快速绿色制备金纳米粒子。与传统方法制备的金纳米粒子相比,绿茶提取液制备的金纳米粒子耐高盐耐酸碱,具有更好的稳定性。将金纳米粒子与VC和AgNO3混合,VC还原AgNO3产生银单质覆盖在金纳米粒子表面,形成金银核壳纳米粒子,导致溶液颜色及波长410 nm处吸光度变化,实现VC的定性及定量分析,基于此将金纳米粒子用于VC的比色分析。最优条件下,VC质量浓度2 mg/L时裸眼观察到溶液颜色由浅粉变为淡黄色;结合紫外-可见光度计检测,波长410 nm处吸光度与VC质量浓度在0.4~120 mg/L范围内呈现良好的线性关系,检出限为0.14 mg/L。将此方法用于VC药片和市售饮料中VC的分析,加标回收率在92.2%~115.0%之间。

In this research,gold nanoparticles(AuNPs)were prepared by reducing HAuCl4 with green tea extract as a reducing and protecting agent,which was rapid and environmentally friendly.The AuNPs were more stable compared with those traditionally prepared using citrate sodium as a reducing agent.In the presence of the new AuNPs,vitamin C(VC)reduced AgNO3 to Ag coated on the surface of AuNPs,leading to the formation of core-shell Au@Ag nanoparticles(AuNPs@Ag)and consequently causing changes in the color of the solution and an increase in the absorbance at 410 nm.VC could be analyzed qualitatively by the naked eyes according to the color change and quantitatively by UV-Vis absorption spectroscopy.When the concentration of VC was 2 mg/L,the solution could be observed to change from pale pink to yellow by the naked eyes.The linear range of VC was from 0.4 to 120 mg/L and the limit of detection(LOD)was 0.14 mg/L.This colorimetric assay was successfully applied to detect VC in VC tablets and drinks with spiked recoveries ranging from 92.2%to 115.0%.