This paper describes a simple, selective and sensitive colorimetric sensing of Cr⁶⁺ ions using β-Cyclodextrin (β-CD) functionalized gold-iron nanoparticles (β-CD/Au-FeNPs). The sonochemically synthesized nanoparticles are winered in colour due to the SPR band of β-CD functionalized bimetalic nanoparticles Au-FeNPs. The capping and stabilizing of Au-FeNPs by redox β-CD is confirmed by FT-IR. The particles are spherical in shape and it posses the effective diameter of 18-20 nm. Under optimized conditions, in the presence of Cr⁶⁺ the wine red Au-FeNPs solution was turned to colourless, accompanying the broadening and red shifting of SPR band. The ratio between the absorbance wavelength at 573 nm to 535 nm (A₅₇₃/A₅₃₅) is linearly correlated with the Cr⁶⁺ concentrations ranging from 50 nM to 500 nM, with a detection limit of Cr⁶⁺ of 2.5 nM was achieved for the first time using β-CD/Au-FeNPs by spectrophotometry. The selectivity of the β-CD/Au-FeNPs towards other interfering metal ions. Finally the proposed method has been successfully employed for the determination of Cr⁶⁺ ion in various industrial waste water with good recoveries.

本文介绍了使用β-环糊精（β-CD）功能化的金铁纳米粒子（β-CD/ Au-FeNPs）对Cr ⁶⁺离子进行简单，选择性和灵敏的比色传感。超声化学合成的纳米粒子由于β-CD官能化的双金属纳米粒子Au-FeNPs的SPR带而颜色泛红。FT-IR证实了氧化还原β-CD对Au-FeNPs的封端和稳定作用。颗粒为球形，有效直径为18-20 nm。在优化条件下，伴随着SPR谱带的变宽和红移，在Cr ⁶⁺存在下，酒红色Au-FeNPs溶液变成无色。573 nm至535 nm处的吸收波长之间的比率（A ₅₇₃ / A ₅₃₅）与50 nM至500 nM范围内的Cr ⁶⁺浓度线性相关，使用分光光度法首次使用β-CD/ Au-FeNPs实现Cr ⁶⁺的检出限为2.5 nM。β-CD/ Au-FeNPs对其他干扰金属离子的选择性。最终，该方法已成功用于多种工业废水中Cr ⁶⁺离子的测定，回收率高。