Thesis (M.Sc.)--Chulalongkorn University, 2009

To develop the simultaneous separation and detection of biomarkers including homocysteine (Hey), glutathione (GSH), and N-acety1-L-cysteine (NAC) using Poly (dimethylsiloxane) (PDMS) microchip capillary electrophoresis coupled with electrochemical detection. Pulse amperometric detection mode for microchip CE was applied to detect these biomarkers. The influences of separation voltage, detection potential, as well as the concentration and pH value of the running buffer on the response of the detector were carefully assayed and optimized. The results clearly show that the determination of homocysteine, glutathione, and N-acety1-L-cysteine by the degree of electrophoretic separation was performed in less than 2 min using a MES buffer (pH 6.0, 25 mM) and 3 mM SDS, with 1200 V separation voltage and +0.8 V detection potential. The detection limits for Hcy, GSH, and NAC were 0.129, 0.224, and 0.232 µM (S/N≥3), respectively. The results obtained should be a step towards developing an automated and reliable microchip CE-ED for clinical analysis.