| Capillary electrophoresis (CE) is a novel and powerful liquid phase separation technique which has attained great acceptance for about 35 years. Because of its short analysis time, easy operation, great simplicity and high separation efficiency, it has been recognized as a useful analytical separation technique. The advent of vari-ous on-line sample preconcentration techniques and the development of detector make up the defect of small sample amount and low detection sensitivity, meeting the needs of trace detection.Recently, a large amount of on-line sample preconcentration techniques have been combined with CE, but the detectors are usually UV/Vis, Mass spectrometry and Electrochemical. CE-AD also has many advantages, therefore, it would be a promising strategy for the separation chemistry if an on-line sample enrichment technique combination with CE-AD established.In this paper, using CE-AD system coupled with on-line sample preconcentra-tion techniques, a new method to determine the sulfonamides, β2-agonists, and sal-via miltiorrhiza was established. The detailed profile in this dissertation is shown as follows.In chapter one, we summarized CE history, technology, separation models, var-ious detection methodologies, application, as well as on-line sample preconcentra-tion techniques utilized in CE.In chapter two, an on-line sample preconcentration method in CE-AD based on a dynamic pH junction was established, and a concentration enhancement of ap-proximately 60-fold was achieved compared with the classical CE-AD methods in the simultaneous analysis of four sulfonamides in milk and meat. The technique is proposed based on the sharp pH change generated at the boundary between an acidic sample and the basic background electrolyte (BGE) zone. Under optimized condi-tions, all analytes were successfully focused and well-separated within 16 min with high efficiency and sensitivity (LODs at S/N=3 ranging from 17 to 46 nM). For the analysis of urine samples by this method, satisfactory recoveries were obtained without a complicated pretreatment step or derivatisation process.In chapter three, a novel transient moving substitution boundary (MSB) method in CE was developed for six β2-agoinsts clenbuterol (CLB),bambuterol (BAM), rac-topamine hydrochloride (RAC), salbutamol (SAL), procaterol (PRO) and formoterol (FOR) analysis. Results indicated that the stacking mechanism of MSB relied on the substitution reaction between 18C6H4-bonded AGs complexes and Na+ at the sub-stitution boundary. The limits of detection (LODs) for clenbuterol, bambuterol, rac-topamine hydrochloride, salbutamol, procaterol and formoterol were 9.0-27.4 nM (S/N=3), respectively.And the detection sensitivities were improved 50 folds, re-spectively. To evaluate the application of the developed method, real sample from pannage was analyzed with recoveries of 95.7% to 105.8%.In chapter four,a simple method based CE-AD was developed and optimized for the determination of 5 water-solubility components of Danshen in samples of compound Danshen dripping pill and Salvia miltiorrhiza. The parameters of the sep-aration electrolyte solution, such as pH and concentration of BGE, were optimized. Best results were performed in background electrolyte (BGE) composed of 15 mM Na2B4O7-45mM NaH2PO4, adjusted to pH 7.0. Under these conditions, complete separation between all L-histidine was achieved within 15 min. The LOD values for the optimized procedure ranged 0.02 mg/L for PAH to 0.1 mg/L for RosA. The methodology was evaluated and validated for the water-solubility components of Danshen and it was found to be reliable for determining in samples of compound Danshen dripping pill and Salvia miltiorrhiza. |
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