甲基紫与苋菜红相互作用的双波长共振光散射比率光谱研究及其分析应用

Studies on interaction between methyl violet and amaranth and its analytical application by dual wavelength resonance light scattering ratiometry

应用双波长共振光散射比率法(DW-RLS)研究了甲基紫与苋菜红之间的相互作用。在pH1.24的乙酸钠-HCl缓冲溶液中,甲基紫和苋菜红本身的共振光散射(RLS)信号均很弱,但是当它们相互作用形成缔合物时,导致RLS信号明显增强并出现新的RLS光谱,适当浓度的Triton X-100存在使结合反应敏化,缔合物最大散射峰位于528nm,RLS信号强度与苋菜红的浓度呈线性关系。通过测量528nm处的RLS强度或两个波长处RLS强度比值(I417/I343),可对苋菜红进行定量检测。当溶液中甲基紫的浓度为1.54×10-5mol/L时,RLS法测定苋菜红的线性范围和检出限分别为0.05～0.50μg/mL和0.02μg/mL,而DW-RLS法的线性范围和检出限分别为0.01～0.60μg/mL和1ng/mL,与RLS法相比较,DW-RLS法受酸度、离子强度等环境条件影响较小,并且有更宽的线性范围和更低的检出限。

The interaction between methyl violet and amaranth was studied using dual-wavelength resonance light scattering ratiometry （DW-RLS）. In pH 1.24 NaAc-HCl buffer solution, the resonance light scattering （RLS） signal of methyl violet or amaranth alone was very weak, but it was enhanced significantly and new RLS spectra appeared when they interacted with each other to form a complex. Moreover, the interaction was sensitized in the presence of appropri- ate concentration of triton X-100 solution. The maximum RLS peak of the complex is at 528 nm, and the RLS intensity is proportional to the concentration of amaranth. By measuring the RLS signals at 528 nan and the RLS intensity ratio （I417/I343）, respectively, the content of amaranth over a wide dynamic range could be detected. Typically, when methyl violet concentration was kept at 1.54 × 10^-5 mol/L, amaranth could be detected over the range of 0.05 - 0.50μg/mL with the detection limit of 0.02 μg/mL using RLS method, while amaranth could be detected over the range of 0.01 - 0.60 μg/mL with the detection limit of 1 ng/mL DW-RLS method. In comparison with RLS method, DW-RLS method was less affected by environmental conditions such as pH, ionic strength etc, and linear range was broader and detection limit was lower.