硫量子点的制备及构建荧光“关-开”型铅离子探针

Preparation of sulfur quantum dots and construction of a fluorescent"off-on"lead ion probe

以升华硫粉、氢氧化钠、聚乙二醇(PEG-4000)、过氧化氢为原料,采用冷凝回流法制备了荧光硫量子点(SQDs),并通过X射线衍射(XRD)、红外光谱(FT-IR)等手段对材料进行了表征。该荧光SQDs最佳激发波长为370 nm,最佳发射波长为451 nm,具备较好的荧光稳定性。实验发现,3,5-二硝基水杨酸(DNS)可使SQDs荧光信号“关闭”,加入铅离子(Pb^(2+))后体系荧光信号重新“打开”,由此构建了“关-开”型探针检测Pb^(2+)的新方法。Pb^(2+)浓度在0~100μmol/L范围内与DNS-SQDs体系的荧光恢复值之间呈良好的线性关系,线性方程为ΔF=0.00167c_(Pb^(2+))+0.96306,线性相关系数(R2)为0.99842,检出限(LOD)为1.90μmol/L,回收率为108.6%~109.4%。该方法成功应用于模拟样品中Pb^(2+)的检测。

By condensation reflux method,sulfur quantum dots(SQDs)with stable fluorescence properties were prepared using sublimated sulfur powder,sodium hydroxide,polyethylene glycol(PEG-4000)and hydrogen peroxide as raw materials.The SQDs were characterized by X-ray diffraction(XRD)and Fourier infrared spectrum(FT-IR).The fluorescence spectrum showed that the optimum excitation and emission wavelength of SQDs were 370 nm and 451 nm,respectively,showing good fluorescence stability.It was found that the fluorescence signal of SQDs can be turned off by 3,5-dinitrosalicylic acid(DNS)and recovered upon adding Pb^(2+).Based on this,a new"off-on"fluorescence probe method for the detection of Pb^(2+)was developed.The recovered fluorescence intensity of DNS-SQDs system was linearly related with Pb^(2+)concentration in the range of 0-100μmol/L,the linear equation wasΔF=0.00167c_(Pb^(2+))+0.96306,the correlation coefficient(R~2)was 0.99842,the detection limit was 1.90μmol/L,and the recovery rates were 108.6%-109.4%.The method has been successfully applied to the determination of Pb^(2+)in simulated samples.