CdSe/CdS量子点荧光探针测定蔬菜中灭蝇胺的残留量

以巯基乙酸(TGA)为稳定剂制备CdSe/CdS量子点(CdSe/CdS QDs)。在弱酸性条件下,灭蝇胺(Cyr)可使CdSe/CdS QDs的荧光增强,据此建立了以CdSe/CdS QDs为荧光探针快速检测辣椒、豇豆、苦瓜、黄瓜和圣女果中Cyr残留的新方法,并优化了Cyr的测定条件。结果表明,当激发波长(λex)为481 nm时,CdSe/CdS QDs的最大发射波长(λem)为580 nm,且不受基质背景荧光干扰。在最优条件下,Cyr在5.0~120 nmol/L范围内与CdSe/CdS QDs的荧光强度增强呈线性关系,相关系数(r)均不低于0.999 1,检出限(LOD,S/N=3)为0.8~1.4 nmol/L,定量下限(LOQ,S/N=10)为2.4~4.6 nmol/L;在4、40、100μg/kg加标水平下的回收率为82.5%~108%,相对标准偏差(RSD,n=3)不大于6.9%。该方法选择性好、灵敏度高、操作简便,应用于实际蔬菜中Cyr的测定,结果满意。

Determination of Cyromazine Residues in Vegetables Using a Fluorescence Probe with CdSe/CdS Quantum Dots

CdSe/CdS quantum dots(CdSe/CdS QDs)were prepared using thioglycollic acid(TGA)as stabilizer.A method was established for the rapid determination of cyromazine(Cyr)residues in pepper,cowpea,balsam pear,cucumber and cherry tomato using the CdSe/CdS QDs as a fluorescence probe,based on the phenomenon that the enhanced fluorescence of CdSe/CdS QDs was observed in the presence of Cyr.Experimental conditions for the determination of Cyr in five vegetables were optimized,including concentration of QDs,pH value,reaction time and coexistence substances.Results showed that the emission wavelength(λem)for CdSe/CdS QDs was 580 nm when the excitation wavelength(λex)was set at 481 nm.Under the optimum conditions,the established method exhibited a good linear in the range of 5.0-120 nmol/L with correlation coefficients(r)not less than 0.999 1.The limits of detection(LOD,S/N=3)and limits of quantitation(LOQ,S/N=10)were 0.8-1.4 nmol/L and 2.4-4.6 nmol/L,respectively.Recoveries at three spiked levels of 4,40,100μg/kg ranged from 82.5%to 108%with relative standard deviations(RSD,n=3)not more than 6.9%.With the advantages of high selectivity,good sensitivity and simple operation,the method was successfully applied in the determination of Cyr in five real vegetables.