| Capillary electrophoresis(CE)is an important separation and analysis technique with high separation efficiency,short analysis time,low sample and reagent consumption.It is especially suitable for precious sample analysis.With its unique advantages,CE has a wide range of applications in the fields of chemistry,biology,environment,medicine,clinical,quality inspection,single cell and single molecule analysis.In recent years,CE has also been used for the characterization and separation of nanomaterials and nanomaterial-conjugates,which has become one of the effective tools for separating nanomaterials.Mass spectrometry(MS),an instrument with high resolution and high sensitivity,when used in conjunction with CE,CE-MS has developed rapidly in the detection of small molecules,metabolomics,and proteomics in complex samples.On the basis of the previous works,the following major innovative researches about the characterization of ligand exchange reactions on QDs and the determination of small molecules in complex samples was carried out by CE:1.CE was used as a novel tool to study the mechanism of ligand exchange reactions on the surface of CdSe/ZnS QDs.2.A new CE-MS method for simultaneous detection of tryptophan(Trp)and its eight metabolites in serum and colon tissue of normal and ulcerative colitis(UC)rats was established.3.A CE-MS platform for the study of competitive uptake between creatinine(Cre)and several drugs was developed.This dissertation consists of four chapters.Chapter 1: The basic definition,properties and applications of QDs were firstly illustrated.And secondly,the several methods of surface functionalization of QDs and several techniques for characterizing nanomaterials were were summarized.Finally,the significance and methods of studying the differences in small molecule metabolism and competitive uptake in complex samples were briefly introduced.Chapter 2: The hydrophobic CdSe/ZnS QDs and 4-mercaptobenzoic acid(4-MBA)were used as a model QDs and the exchange ligand,respectively.The ligand exchange process on the surface of CdSe/ZnS QDs was characterized by CE for the first time,and the effect of reaction time and ligand concentration on ligand exchange kinetics and the extent of ligand exchange reaction was also investigated.Combined with UV-vis absorption spectroscopy,fluorescence spectroscopy and Fourier transform infrared spectroscopy(FT-IR),the mechanism of ligand exchange reaction on CdSe/ZnS QDs was discussed.Compared to the traditional methods,the established method by CE was simple,fast,and do not require any purification steps.Thus,CE is expected to be a promising technique for characterizating the ligand exchange of QDs and can be used to guide the selective functionalization of QDs for various applications.Chapter 3: A CE-MS method was developed for analysis of Trp and its eight metabolites,and the conditions of background electrolyte(BGE)and sheath liquid(SL)were optimized.Under the optimal conditions,the reproducibility and sensitivity of this method was investigated.The RSD of relative migration time for intra-and inter-day was 0.96%-1.37% and 1.06%-3.42%,respectively.The RSD of the relative peak area for intra-and inter-day was 2.26%-11.78% and 1.16%-13.05%,respectively.The limits of detection(LOD)and the limits of quantitation(LOQ)was in the range of 0.05-5.0 ng/mL and 0.5-10.0 ng/mL,respectively.This CE-MS method was also used for the detection of Trp and its eight metabolites in serum and colon tissues of normal and UC rats.Chapter 4: A CE-MS method for the simultaneous analysis of creatinine and metformin(MFM),p-aminohippuric acid(PAH),digoxin(DGX),and ketoconazole(KCZ)was established.This method has good reproducibility and high sensitivity.The reproducibility and sensitivity of the method was investigated.The RSD of relative migration time for intra-and inter-day was less than 1.5%.The RSD of relative peak area for intra-and inter-day was less than 11%.The LOD and LOQ was in the range of 0.2-50.0 ng/mL and 2.0-100.0 ng/mL,respectively.Furthermore,with MFM and PAH as model drugs,the renal tubular uptake of creatinine was evaluated. |
