Synthesis Of Europium-based Fluorescent Probes For The Detection Of Phosphate In Waters

Phosphorus is an extremely important element in nature,but also one of the key factors causing eutrophication of aqueous system.In order to effectively control eutrophication phenomenon,the concentration of phosphate ions?Pi?in waters must be determined effectively.In recent years,the fluorescence analysis method has attracted much attention in the environmental field,because it has the advantages of simple operation,high sensitivity and good selectivity.The rare earth coordination polymers have the unique fluorescent characteristic and the adjustable structure,and there exists strong binding force between lanthanide europium ions and phosphate,so we choose europium-based infinite coordination polymer?Eu-ICP?as a kind of fluorescent chemosensor.For the actual water samples of phosphate analysis,the regular sampling method is difficult to reflect fully and objectively the water quality safety situation,spatial and temporal distribution,as well as real-time chemical state of phosphate.Therefore,we employ the diffusive gradients in thin-films?DGT?technique to detect Pi concentration,in which the fluorescent chemosensor composed of cadmium telluride quantum dots?CdTe QDs?and europium ions,is selected as the DGT binding phase.Furthermore,we explore the feasibility and accuracy of the system in the analysis of actual samples.The main results are given as follows:1.Eu-ICP nanospheres are rationally constructed by a facile one-step solvothermal treatment,and their structure and morphology can be modulated by changing reaction conditions.The as-obtained Eu-ICP nanospheres have excellent fluorescence properties and good structural stability in waters.Moreover,the corresponding fluorescence intensity is not influenced by pH and ionic strength of the solution to some extent.Eu-ICP nanospheres can be used as an effective fluorescent probe to selectively determine the concentration of phosphate in the water,which has a good linearity ranging from 2?100 pM and a low detection limit of 0.83 ?M.To assess the accuracy of the fluorescent probe,Eu-ICP nanospheres are used to detect the phosphate in the real water samples,accompanied by the satisfactory recovery and relatively low standard deviation.Besides,the sensing mechanism of Eu-ICP nanospheres for phosphate is investigated,which is verified through a series of structural and morphology characterizations after the interaction between Eu-ICP nanospheres and phosphate.Overall,the newly developed Eu-ICP probe features ease of synthesis,good water solubility and stability,high sensitivity and specific recognition function,rationalizing its suitability for the Pi analysis in the complex aqueous systems.2.TGA-capping CdTe QDs are synthesized via the reflux technique,which can be utilized as a fluorescent probe?CdTe QDs/Eu3?together with lanthanide Eu3.Importantly,the intensity of the obtained fluorescent probe is hardly influenced by pH and ionic strength of the solution to some extent.At the same time,the fluorescent probe has excellent selective response to the phosphate ions,good linear range,accompanied by 10?200 ?M of the linear detection range and 1.58?M of the detection limit.Additionally,the probe is selected as the DGT binding phase and put into the DGT devices with the known concentration of the phosphate solution.And the diffusion coefficient of CdTe QDs/Eu³⁺-DGT is calculated by recording the fluorescence intensity of binding phase solution at different intervals.The Pi concentration in the natural water spiked is measured,similar to the value based on the standard method,which proves the feasibility and accuracy of the current analytical method.