Study On Capillary Electrophoresis With Amperometric Detection In Bioanalytical Chemistry

Capillary Electrophoresis (CE) is one of the most important and rapidly growing separation techniques in recent twenty years, It absorbed the virtues of both the conventional electrophoresis and modern High Performance Liquid Chromatography (HPLC), Because the theoretical plate number is great developed to tens of thousands and even millions and the volume of sample injection reaches nano milliliter level in CE analysis, CE includes many separation patterns, it is studied and applied to most analytical areas. And excellent prospects of CE have been shown in the fields of pharmaceutical analysis, biochemical analysis, food analysis, and environmental analysis. However, the small sample injection volume and very thin capillary bring about difficulties to detections. The common used detection methods are Ultra-violet (UV), Laser Induced Fluorescence (LIF), Luminescence Detection, Mass Spectra (MS). Every detection method performs some advantages and suffers from some shortages too. For example, LIF and MS are very sensitive but the instruments are very expensive, and some complicated derivation procedures are needed. Amperometric detection (AD), one kind of Electrochemical Detections (ED), is more sensitive than the common used UV detection, and have many merits on when it coupled with CE, such as simple instrument and operation, low cost, wide linear range, small dead volume, etc. So the combination of CE with AD is extensively studied and applied in most analytical fields for its above advantages.The advantages of CE in separation efficiency and instruments are obvious when compared to HPLC. However, the concentration detection sensitivity of CE is much lower than HPLC owing to its smaller sampling volume and the short light distance when coupled with UV or LIF detectors. The detection sensitivity of CE could be greatly improved by some special characters of itself such as electro-stacking and Field-amplification- Injection (FAI) and Isotachophoresis (ITP).This dissertation is to study on Capillary Electrophoresis with Amperometric detection (CE-AD) of biochemical analysis, and it also explores the methods of improving the sensitivity of CE-AD. The methods include electro-stacking and Field-amplification-Injection (FAI) and Isotachophoresis (ITP).The contents of this dissertation include four chapters:In the first chapter, it introduced the characteristics of CE, the separation modes and injection technologies of CE, sample enrichment technologies, the sensitivity-enhanced methods, the progress of CE-AD are discussed. The goal and significance of this dissertation are introduced too. 196 references are cited in this dissertation.Chapter 2 is determining the small water-soluble antioxidants in plasma by CE-AD. The small water-soluble antioxidants in plasma including GSH, UA, Try and Cys are very important to human being health and their detection is significant too. The optimum conditions of determining GSH, UA, Try and Cys by CZE-AD based on metallic copper electrode were detailed studied. The optimum conditions of CZE-AD were separation voltage 15 kV, running buffer 25mmolL-1 Na2B4O7- 50molL-1 NaH2PO4 (pH 7.9) , kinetic injection time 30 s and detection potential 0.5 V. The linear ranges of the four analytes were (1.0-5.0) ×10-6-5.0×10-4molL-1 and the limits of detection were about 10-6molL-1 under the optimal experimental conditions. This method performed some advantages in quickness, high sensitivity and simple instrumentation, and satisfactory results were obtained when it was applied to analyzing human plasma samples.The indirect determination of the contents of RNA in yeast by analyzing adenine (A) and guanine (G) with Capillary Electrophoresis with Amperometric Detection (CE-AD) was reported in chapter 3. The effects of potential of working electrode, running buffer, separation voltage and injection time on the CE - AD determination were investigated. Adenine and guanine could be well separated in a 30 mmol/L borate buffer (pH 9. 0) within 18 min under the optimum conditions. Their detection limits of adenine (S/ N = 3) of 2.0 ×10-7 mol/ L and 1.7 ×10-7mol/ L , respectively. The experimental results showed that this method was of high sensitivity and high repeatability, and potential to be used in the quick analysis of Yeast in foods.In the chapter 4, the method of transient capillary isotachophorsis with AD was studied.