| This work combines capillary electrophoresis and ultraviolet detection technology and use the amplifier and nanomaterials field amplified sample(FASI)to study the combination,graphene quantum dots as the nanometer material has larger specific surface area,good biocompatibility and stable physical and chemical properties,etc,and through the application of graphene quantum dots,sample enrichment effect is obvious,The detection sensitivity has been greatly improved.The thesis is divided into four chapters.In the first chapter,the development and application of capillary electrophoresis are reviewed,including the separation and detection methods of capillary electrophoresis are briefly introduced.Nanomaterials and the application of nanomaterials in capillary electrophoresis are introduced,and the development status,advantages and disadvantages of quantum dots,graphene quantum dots and doped quantum dots and their applications in analytical chemistry are discussed,paving the way for subsequent experiments.In the second chapter,the separation and detection of algae DNA in shallow water was completed by capillary gel free screening electrophoresis with hydroxypropyl methyl cellulose(HPMC)as screening medium,and before the sample injection period of graphene quantum dots column,Graphene Quantum Dots can make use of the principle of?-?stacking and sample adsorption in the buffer environment,for sample enrichment.In this experiment,the effects of the concentration of sodium dihydrogen phosphate and dissodium hydrogen phosphate mixed buffer solution,EDTA concentration in the mixed solution,p H of buffer solution,separation voltage,type and concentration of screening media on the detection of algae genome in shallow water were investigated.Finally,the optimal experimental conditions for DNA detection of shallow water algae are as follows:The concentration of buffer solution is 25 mmol/L,the concentration of EDTA is 3 mmol/L,the p H of buffer solution is 7.3,the content of hydroxypropyl methyl cellulose is 0.7%,and the injection time of graphene quantum dots is 5 s.Compared with conventional electric injection,the injection time can be greatly shortened to 20 s by pressure injection.At the same time,graphene quantum dots were used as the carrier to enrich DNA molecules,which greatly improved the detection sensitivity.The linear range of DNA detection of four shallow water algae by this method is as follows:Chlamydomonas,y=-24.947x+33.748,Anabaena pseudofishy,Y=-24.085x+35.184,Gonostia,Y=-23.879x+36.299,Streptomydomonas,Y=-28.228x+35.194,the detection limit is,2.60 x 10-5g/L.Algae in water samples the high sensitive detection of DNA,the recovery rate is respectively:chlamydomonas,95.73%,false fishy,99.03%,boat,95.92%,linear,98.53%,relative standard deviation less than 5%.In chapter 3,melamine and diccyanamide were separated and detected by capillary electrophoresis using graphene quantum dots(GQDs)amplification.Firstly,sulfur-doped graphene quantum dots(S-GQDs)were prepared by pyrolysis method.Compared with undoped graphene quantum dots(GQDs),the introduction of S atoms can improve some characteristics of GQDs to a certain extent.Including their surface states and chemical properties,and enhance the dot's ability to interact with charged ions,making it easier to trap positive charges.Using S-GQDS as the sample carrier,the two enrichment techniques were combined to achieve double amplification of the sample,and then the separation and detection of melamine and dicyandiamide were performed by capillary electrophoresis(CE).In the experiment,the composition and p H of buffer solution,the volume fraction of S-GQDs in buffer solution,the injection time and many other factors that can affect the effect of sample enrichment and separation were investigated.When the p H of buffer solution is adjusted to 4.6,the injection time can be increased to 450 s.Compared with conventional electric injection,the sensitivity of the samples was significantly increased by 1.6×10~5times after using FASI and S-GQDS techniques combined with double amplification.This method has been successfully used for the detection of melamine and dicyandiamide.The linear function of the two is 1×10-14?1×10-8mol/L,the detection limit of melamine is2.6×10-15mol/L,and the detection limit of dicyandiamide is 5.7×10-15mol/L.At the same time,metformin hydrochloride was used as the actual sample to detect the melamine and dicyandiamide with high sensitivity.The recoveries of melamine and dicyandiamide were 95.9%?102.4%and 92.0%-106.0%respectively,and the relative standard deviation(RSD)of the detected results was less than 5%.In chapter 4,electrokinetic preconcentration of samples in capillary electrophoresis is realized by adjusting electrokinetic seepage,sample in capillary electrophoresis using streptomycin sulphate and kanamycin sulfate in buffer solution migration rate of different implements the separation and detection of two substances,sulfur and nitrogen doping makes the surface of graphene quantum dots have many hydroxyl and carboxyl,Moreover,the sample was enriched by its large specific surface area and its ability to adsorb kanamycin sulfate and streptomycin sulfate.This experiment investigated the concentration of sodium borate and sodium dihydrogen phosphate mixed buffer solution,the p H of buffer solution,operating voltage,injection time and other influencing factors.Finally,the optimal detection and separation conditions of the two antibiotics were obtained:buffer solution concentration of 30mmol/L,p H 9.18,separation voltage of 12 k V,sampling time of 15 s,adding doped graphene quantum dot time of 3 s.The linear function of the two antibiotics was kanamycin sulfate:Y=-25.950 X+216.03,and streptomycin sulfate:Y=-35.062x+290.85.The limit of detection was 1.26×10-9mol/L,and the recoveries were 99.1%and 98.7%,respectively. |
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