甲醛功能化聚乙烯亚胺/曙红Y比率荧光法测定六偏磷酸钠

在微波辅助条件下，合成了甲醛功能化的聚乙烯亚胺(FPEI)，在激发波长为340 nm时，FPEI的荧光发射波长470 nm，紫外灯下发蓝色荧光。在此激发条件下，曙红Y(Y eosin Y, EY)的荧光发射波长为540 nm，发绿色荧光。在酸性介质中，FPEI和 EY 通过静电作用形成FPEI/EY复合物，导致EY 在540 nm 的荧光显著猝灭，而FPEI本身的荧光只有微弱的降低。当加入六偏磷酸钠(SHMP)时，SHMP、EY与FPEI发生竞争结合，由于SHMP与FPEI表面质子化氨基的静电作用强于EY，EY从FPEI/EY复合物中释放导致540 nm荧光强度逐渐恢复。当SHMP与FPEI/EY 混合时，EY 540 nm荧光强度与FPEI 470 nm 荧光强度的比值(F₅₄₀/F₄₇₀)与SHMP浓度呈较好的线性关系，在紫外灯照射下体系的荧光由蓝色逐渐变为绿色，由此建立了FPEI/EY比率荧光快速测定SHMP的新方法。在最优条件下，线性范围为0.1~4.2 μmol·L-1，检出限(3σ)为38 nmol·L-1。该方法选择性好、简单、快速, 已成功应用于茶饮料中SHMP的分析检测。

Determination of Sodium Hexametaphosphate by Ratiometric Fluorescence Method Based on Formaldehyde Functionalized Polyethyleneimine/Eosin Y System

Under the condition of microwave assisted,formaldehyde functionalized polyethyleneimine(FPEI)was synthesized.The maximum emission of FPEI at 470 nm was obtained when the excitation wavelength was set at 340 nm,and the blue fluorescence was easily observed under an ultraviolet lamp.Under this excitation condition,the fluorescence emission peak of the Eosin Y(EY)was located at 540 nm,and the green fluorescence was observed.In acidic medium,the EY and FPEI form a complex through electrostatic interaction.The formation of the FPEI/EY complex resulted in the quenching of EY fluorescence at 540 nm,while the fluorescence intensity of FPEI was only slightly reduced.In the presence of sodium hexametaphosphate(SHMP),competitive binding occurred between SHMP,EY and FPEI.Because the electrostatic interaction between SHMP and protonated amino groups on FPEI surface is stronger than that of EY,EY was gradually released from the PEI/EY complex,resulting in the recovery of EY fluorescence at 540 nm.The fluorescence change ratio between the fluorescence intensity of Ey at 540 nm and the fluorescence intensity of FPEI at 470(F 540/F 470)has a good linear correlated with the concentration of SHMP,and a noticeable blue to green changed under an ultraviolet lamp if SHMP solution was mixed with the FPEI/EY.Based on the phenomena,a novel rapid ratiometric fluorescence method for determination of SHMP was developed.Under the optimized conditions,the linear range is 0.1~4.2μmol·L^-1,and the limit of detection(3σ)was 38 nmol·L^-1.The proposed method is of high selectivity,simple and rapid,and is successfully applied to determine the concentration of SHMP in tea drink samples.