Quantum Dot-based Capillary Electrophoresis Electrochemiluminescence System For The Detection Of Amines

In this paper,the application of quantum dot modified working electrodes in Electrochemiluminescence?ECL?technology of samples separation based on capillary electrophoresis?CE?was explored.The ECL performances of CdSe quantum dots?CdSe QDs?and graphene quantum dots?GQDs?as nano-luminescent materials were also researched.They were successfully applied to the detection of clenbuterol,melamine,dicyandiamide and so on.At the same time,the application of new CE QD's ECL system was developed.The research not only expanded the new detection method of CE,but also broadened the application field of QD's ECL,which showed practical application value.In Chapter ?,the development and application of capillary electrophoresis,electrochemiluminescence,quantum dots and graphene quantum dots were summarized.Meanwhile,the main development fields and current situation of them were described in detail.Based on the advantages of CE,ECL and QDs,a new idea for developing a sample analysis system was proposed,which paved the way for subsequent experiments.In Chapter ?,the enhancement of electrochemiluminescence of CdSe quantum dots by amine molecules was studied,and the electrochemiluminescence sensor of CdSe quantum dots was constructed.A new method of capillary electrophoresis?CE?quantum dots?QDs?electrochemiluminescence?ECL?based on reverse micellar sweeping preconcentration was developed for simultaneous separation and detection of ractopamine and clenbuterol.The capillary was first filled with buffer solution containing sodium dodecyl sulfate?SDS?micelles.When electrokinetic injection was used,the sample molecules enter the capillary and were captured and enriched by the SDS micelles coming in the front of the entrance.After separation by CE,they entered the detection end sequentially.According to the enhancement effect of different concentration of amine molecules on the luminescence intensity of CdSe quantum dots,the simultaneous separation of different amine molecules could be realized.Micellar reverse sweeping enrichment technology made the micelle-sample conjugate in a quasi-stationary state in capillary,the injection time could reach 50 minutes,and the electrochemiluminescence signal of quantum dots could be enhanced 6000 times.The method had been successfully applied to the simultaneous separation and detection of ractopamine and clenbuterol in pork samples with linear ranges of?0.8000-2960??g/L and?3.000-5520??g/L,with detection limits of 96.80 ng/L and 192.5 ng/L,respectively.In Chapter ?,based on the characteristics of carbon-based nanomaterials,such as high luminescence intensity,low toxicity and environmental friendliness,the synthesis methods of new carbon quantum dots were summarized,and the most practical and effective method-pyrolysis of citric acid to prepare graphene quantum dots?GQDs?was explored.The electrochemiluminescent behavior of GQDs was studied.The electrochemiluminescent sensor of GQDs was successfully constructed.The simultaneous detection of oleylamine and diethylamine was realized by capillary electrophoresis.The detection limits were 2.930 mol/L and 2.400 mol/L,respectively.The average recovery of oleamine was 98.5%?RSD 1.2%¹.5%?and diethylamine was99.5%?RSD 1.0%¹.3%?.The accuracy and precision of the detection results were within the confidence range,which confirmed the validity of the method.In Chapter ?,melamine and dicyandiamide were selected as model detection substances.They were added to GQD's electrochemiluminescent sensors system respectively.Itwasfoundthatbothofthemcouldenhancethe electrochemiluminescent signal of GQDs.On this basis,a GQD's ECL system based on CE?CE GQD's ECL?was constructed to separate and detect melamine and dicyandiamide simultaneously.Then,by adding SDS in the detection solution,adjusting the pH,and using the negative charge characteristics of SDS in the solution to enrich positive ions,the detection signal could be amplified and the sensitivity could be improved,again.The electrochemiluminescence signal of quantum dots was enhanced 7000 times.There was a linear correlation between melamine and dicyandiamide in the range of 5.000×10^-81.000×10^-4mol/L,respectively.The detection limits were 27.30 nmol/L and 46.24 nmol/L,respectively.