| Capillary electrophoresis (CE) is one of the most important separation techniques in last twenty years. CE is the technique of performing electrophoresis in buffer-filled, narrow-bore capillaries, with a high-voltage power supply providing electric field; separation by electrophoresis relying on the differences in the speed of migration (or migration velocity) of charged species. In CE analysis, the volume of sample injection reaches nano liter level. CE has been widely applied in many fields, including analytical chemistry, medicinal chemistry, enviromental chemistry, food chemistry, biological chemistry, and so on. The present dissertation described the studies of CE, coupling amperimertric detection (AD) or laser induced fluoscence detection (LIF), application in the analysis of food contaminants and disease markers in real-world. The major contents are described as follows:1. PrefaceThe characteristics, the basic theories, the separation models, the detectors, the studies and applications of CE are introduced briefly. The goal and significance of this dissertation are also introduced.2. A novel capillary electrophoretic method for determining methylglyoxal and glyoxal in urine and water samplesTwo non-electroactive biomarkers methylglyoxal (MGo) and glyoxal (Go) in urine and environmental water samples were determined for the first time by capillary electrophoresis with amperometric detection (CE-AD) after derivatising with an electroactive compound2-thiobarbituric acid. Experimental conditions of derivatization and CE-AD detection were optimized. Highly linear response was obtained for these two biomarkers over three orders of magnitude with good correlation (r2>0.9991). The limits of detection (LODs) and limits of quantitation (LOQs) of MGo and Go were0.2μg/L and1.0μg/L,0.5μg/L and2.0μg/L, respectively. The average recovery and relative standard deviation (RSD) were within the range of90.9-101.3%and0.7-2.2%, respectively. The proposed CE-AD method provides a reliable and sensitive quantitative evaluation of MGo and Go in real sample matrices by employing relatively simple and inexpensive instrument.3. Fast analysis of catecholamines and metabolites in human urine by capillary chromatography with amperometric detectionThe urinary metabolic marker compounds, namely norepinephrine (NE), epinephrine (E), dopamine (DA), metanephrine (M), vanillylmandelic acid (VMA) and homovanillic acid (HVA) of cathecholamines were detected by capillary chromatography with amperometric detection (CE-AD). Electrophoretic runs were performed in an80mmol/L H3BO3-Na2B4O7running buffer (pH9.48) at a separation voltage of16kV, and the six marker compounds together with the major coexisting compound uric acid (UA) could be well separated within24min. Highly linear response was obtained for the six markers over three orders of magnitude with detection limits ranging from1.0to5.0μg/L (S/N=3). The proposed CE-AD method has been used to detect the six markers simultaneously in urine samples with the advantages of obtaining more diagnostic information of several diseases and avoiding redundant measurements and high assay cost. Thus, it could provide useful information for clinical researchers as a fast and simple analytical method.4. Determination of DNA damage markers:8-hydroxy-2’-deoxyguanosine and8-nitroguanine by capillary electrophoresis in urine8-hydroxy-2’-deoxyguanosine (8-OHdG) and8-nitroguanine (8-NO2Gua) have been widely used as markers of DNA damage in both animal models and human studies. Owing to the low level of8-OHdG and the complex matrix, measurement of8-OHdG and8-NO2Gua in urinary samples was a challenging work. In this paper, we have developed a sensitive and low-cost method for the determination of the two types of markers by capillary electrophoresis with amperometric detection (CE-AD) after solid phase extraction (SPE). In the spiked urine samples,8-OHdG and8-NO2Gua were well separated from other urine components, exhibiting a linear calibration over the concentration range of0.1～50μg/mL with the detection limits varied from0.08μg/mL to0.10μg/mL. The relative standard deviation (RSD) was in the range of0.14%and1.58%for peak area,0.14%and0.20%for migration time, respectively. Under optimized conditions, the proposed CE-AD method has been applied to quantitative evaluation of8-OHdG and8-NO2Gua in urinary samples from healthy volunteers and cancer patients. It was found that the levels of8-OHdG and8-NO2Gua in cancer patients were significantly higher than those in healthy ones.5. Measurements of amino acids by capillary electrophoresis with laser induced fluorescence--potential application in inborn errors of metabolismA method of capillary electrophoresis coupled with laser induced fluorescence detection has been developed for the determination of markers of six kind diseases of new-born babies. Factors influencing the separation and detection were examined and optimized. Highly linear response was obtained for markers with over three orders of magnitude with good correlation (r2>0.9970). The average revovery and RSD were within the range of90.9-103.4%and0.2-1.9%, respectively. The LODs were ranged from0.01-5.0nmol/L. The proposed CE-LIF method provides an inexpensive and sensitive quantitative evaluation of markers for the purpose of fast diagnose of some metabolic diseases of new-born.6. A novel capillary electrophoretic method for determining aliphatic aldehydes in food samples using2-thiobarbituric acid derivatizationA novel electrophoretic method for sensitive determination of nine aldehydes, including formaldehyde (C1), acetaldehyde (C2), propanal (C3), butanal (C4), pentanal (C5), hexanal (C6), glutaradehyde (Gla),2,3-butanedione (Bud) and methylgloxal (MGo) in food samples has been developed based on CE with amperometric detection (CE-AD). After derivatized with an electroactive compound2-thiobarbituric acid (TBA), these nine non-electroactive aldehydes were converted to electroactive adducts, therefore detectable by CE-AD approach. Experimental conditions of derivatization and CE-AD detection were optimized. The proposed method was validated according to International Conference on Harmonization (ICH) requirements with recovery results ranging from82.8to123.8%. Calibration plots of aliphatic aldehydes were linear (r2≥0.9901) in the concentration range from0.083 to15.0mg/L. The LODs were between0.008and0.074mg/L. The proposed CE-AD method provides a reliable and sensitive quantitative evaluation for non-electroactive low-molecular-mass monoaldehydes and dialdehydes in real sample matrices by employing relatively simple and inexpensive instrument. |
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