Preparation,Separation,structure Analysis Of Carbon Quantum Dots Derived From Chitosan And Its Application On The Detection Of Nitrophenol Isomers

As a novel nanomaterial,carbon quantum dots(CQDs)has received much attention since its inception due to its excellent optical performance,good water solubility,lower cytotoxicity,superior chemical inertness and better biocompatibility.It has been applied to many fields such as biological imaging,photo catalysis,analysis detection and optoelectronic devices.However,the fluorescence quantum yield of CQDs is lower than that of traditional semiconductor quantum dots generally and the CQDs prepared by various methods are often mixtures with different sizes and different structures.So the further application of CQDs is limited.It also limits the understanding of the interaction mechanism between CQDs and other materials.To improve the preparation method or through surface modification and other means to obtain high fluorescence quantum yield of CQDs has become a hot spot in the field of CQDs research as same as to separate CQDs mixture and further analyze structure.In this paper,the preparation,separationand structure analysis of CQDs were studied systematically.The detection and identification of nitrophenol isomers by using CQDs was also investigated.The specific work as follows:1.CQDs were synthesized by hydrothermal method by using chitosan as carbon source.The prepared CQDs were characterized by transmission electron microscope(TEM),infrared spectroscopy(IR),nuclear magnetic resonance(NMR),Ultraviolet spectrum(UV),fluorescence spectrum,nuclear magnetic resonance spectrum(NMR)and X-ray diffraction(XRD).2.High performance liquid chromatography(HPLC)was used for the separation and preparation of CQDs.Four components were collected and analyzed by HPLC-MS-MS.Their possible structures were deduced.3.It was proved that cyclodextrin was successfully modified onto CQD by HPLC/MS/MS analysis.The effects of different condition on the fluorescence property of β-CD/CQDs were investigated.Based on the study of the interaction between the-CD/CQDs and the three isomers of nitrophenol,the detection and recognition of the o-nitrophenol,m-nitrophenol,p-nitrophenolisomers byβ-CD/CQDs was realized.