Preparation Of Quantum Dots-molecularly Imprinted Composite And Its Application In Rapid Determination Of Tetrabromobisphenol A

Tetrabromobisphenol A?TBBPA?is one of the most widely used brominated flame retardants?BFRs?,and presents in various environmental media.Furthermore,TBBPA can enter the human body through the environment media,even is found in human blood,breast milk and umbilical cord blood.TBBPA had harmful effects on endocrine disrupting toxicity,neurotoxicity,developmental toxicity,reproductive toxicity and immunotoxicity.Therefore,the establishment of rapid detection of TBBPA in environmental media is of great significance to protect the ecological environment and human health.The main methods for TBBPA detection are chromatography and chromatographic-mass spectrometry.Although the results of these methods are more accurate,the chromatography and mass spectrometry equipment is expensive,and the pretreatment process is relatively cumbersome and lack of selectivity.The optical sensing method has high sensitivity and easy operation compared with the traditional detection method.Therefore,in this study,we combined the excellent optical properties of quantum dots with the high selectivity of molecular imprinting technology to prepare a novel quantum dot molecularly imprinted composite,which is used as a recognition element to construct highly rapid and selective fluorescent sensor.This developed sensor is used in the rapid detection of TBBPA in electronic products.The research content is divided into two parts:Chapter I Preparation of CdTe quantum dots and evaluation of its fluorescent performanceObjective:We prospectively prepared water-soluble CdTe quantum dots?CdTe-QDs?with good optical properties.,which were an optical matrix materials for the preparation of quantum dot molecularly imprinted composite.Methods:CdTe-QDs was prepared by one step based on the modified mercapto aqueous phase method using CdCl₂·2.5H₂O and K₂TeO₃ as precursors.The preparation conditions,including the ratio of Cd²⁺to Te⁴⁺,pH value,the coordination solvent type and dosage,reflux time,reaction temperature,were systematically optimized and discussed.The structure and morphology of CdTe-QDs were characterized by transmission electron microscope?TEM?,fourier transform-infrared spectrometer?FT-IR?,X-Ray diffractomete?XRD?.Results:The optimized preparation conditions were reduced glutathione?GSH?as the coordination solvent,pH=10,Cd:GSH:Te=4:1.44:5,the reflux time of 60minutes and the reaction temperature at 100°C,and the fluorescence intensity of CdTe-QDs was the strongest under these conditions.The quantum yield was 64%and the diameter was in the range of 8-10 nm.Conclusions:The water-soluble CdTe quantum dots with good optical properties were successfully prepared.The optical performance of CdTe-QDs is stable and is expected to be used as a fluorescent element for rapid sensing studies.Chapter ? Preparation of QDs-molecular imprinting composite and its application for the rapid determination of tetrabromobisphenol AObjective: We prospectively synthesized a new QDs-molecularly imprinted?QDs-MIPs?composite for the selective recognition of TBBPA,and developed a fluorescent sensor for rapid determination of TBBPA in electronic products based on QDs-MIPs composite.Methods: Based on surface molecular imprinting technology,a novel QDs-MIPs composite was prepared by grafting molecularly imprinted polymers?MIPs?onto the surface of Cd Te-QDs with TBBPA as template molecule.The synthesis conditions of QDs-MIPs composite were systematically optimized,and the prepared QDs-MIPs composite was characterized by TEM,FT-IR,XRD.Using this QDs-MIPs composite as specific recognition element,a rapid and sensitive fluorescent sensor was developed and the fluorescent detection conditions were systematically assessed,and then the methodological evaluation of the constructed fluorescent sensor was carried out.Furthermore,this fluorescent sensor was successfully used to determine TBBPA in electronic products.Results: Under the optimal preparation conditions,QDs-MIPs composite had high adsorption capacity of 88.2 mg g-1 for TBBPA,and the imprinting factor?IF?was 12.1,which indicated good imprinted effect for TBBPA.The results of selectivity evaluation also demonstrated that this composite had excellent selectivity for TBBPA.Under the optimal detection conditions,the calibration plot of developed fluorescent sensor was linear in the range 1-60 ng m L-1 for determination of TBBPA,and the limit of detection?LOD?was 0.32 ng m L-1.Finally,this fluorescent sensor was applied to detect TBBPA in electronic products,and satisfactory results were obtained.The spiked recovery of this method was in the range 89.59-107.87% with the relative standard deviation?RSD?of 0.88-6.23%,and the results showed good agreement with that obtained from the HPLC-UV method.Conclusions: A rapid and sensitive fluorescent sensor with QDs-MIPs composite as a specific recognition element was constructed.This fluorescent sensor can be used for rapid detection of TBBPA in electronic products.