关键词: 绿茶提取液；金纳米粒子；VC；比色分析

Abstract: 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%.

Key words: green tea extract; gold nanoparticles; VC; colorimetric analysis