构建碳点—罗丹明B比率探针检测汞离子污染

A dual emission ratiometric probe for mercury ion

双发射比率探针以其优良的抗干扰性能成为近年来荧光探针研究的热点.本文采用微波法合成碳点,并构建了碳点-染料的新型比率探针,可以用于定量检测汞离子(Hg2+)污染.该比率探针检测汞离子的线性范围为0.56~5.0μmol·L-1,检出限为0.56μmol·L-1.随着汞离子浓度的增加,比率探针体系在紫外灯下的颜色会从紫色逐渐变化为橙色,从而实现汞离子的可视化筛查.实验发现在汞离子检测中,当其他金属离子的浓度为汞离子浓度10倍时,比率探针对汞离子仍有较强的选择性.使用此方法对实际自来水样品进行了检测,自来水中没有检出汞离子;而在自来水的3种浓度汞离子加标回收实验中,加标回收率均为91.17%~104.83%.

Compared to single emission probe,dual emission ratiometric fluorescence probe can effectively avoid interference from environment factors and instrument variations.Thus ratiometric probes demonstrate good stability,high reproducibility and good reliability.Carbon dots with uniform size and good water solubility were synthesized.A dual emission ratiometric fluorescent probe based on carbon dots and rhodamine B was made to detect mercury ions.The probe was made via electrostatic interaction between carbon dots and rhodamine B.Rhodamine B was used as internal reference with stable fluorescence independent of changes in mercury ion concentration.The fluorescence ratio of the probe(carbon dot/rhodamine B)changed with the concentration of mercury ion with good linearity from 0.56~5.00μmol·L-1,with a detection limit of 0.56μmol·L-1.With increasing mercury ion concentration,fluorescence of the ratiometic probe gradually changed from purple to orange with UV excitation,as observed by the naked eye.Visual inspection of mercury ion concentration has great value for potential applications in on-set testing.Interference from Li+,Na+,Ag+,Ca2+,Al3+,Co2+,Cu2+,Mg2+,Ni+,Pb2+,Zn2+,Fe2+and Fe3+was not observed at metal ion concnetrations of<10 times of Hg2+.Carbon dots detect mercury ion selectively due to their surfacebound hydroxyl,carboxyl and other groups which bind mercury ion far stronger than other metal ions.This ratiometric method therefore shows good selectivity and high sensitivity when used to detect mercury ions in tap water,with a spike recovery rate from 91.17%~104.83%.In conclusion,mercury ion detection by the dual-emission ratiometric fluorescent probe has good specificity,high selectivity,high accuracy and can be used in complex matrix.