A Novel Method For Separation And Detection Of Metal Ions By Capillary Electrophoresis Chemiluminescence

In the past years, capillary electrophoresis(CE) has gained significant acceptance in the modern analytical laboratory. This technique yields highly efficient separations while requiring only amounts of sample. The constraints of on-column detection generally result in poor detection limits and have reduced the overall application of CE.Chemiluminescence(CL) detection has been shown to be a highly sensitive detection method. Due to its simple optical system and low background nature, CL is expected to be an ideal detection method for CE. CE-CL technique has received significant attention over the past several years. The research results obtained in the thesis are listed as follows: Separation and detection of metal ions are important in both environmental and biological applications. The main disadvantage of conventional methods are high costs, and some require tedious pre-column treatments and require large amount of analyte. In the previously used interface for CE-CL detection, the presence of gas bubbles in the reaction capillary due to decomposed hydrogen peroxide in alkaline solution would affect the stability of the current and background, therefore ,would disturb the detection. CL(luminol with potassium ferricyanide ) detection with CE for metal ions analysis has not yet been reported. Based on the fact that some metal ions can catalyze the chemiluminescence (CL) reaction of luminol with potassium ferricyanide, a novel capillary electrophoresis CL method was developed for the determination of Co(Ⅱ)and Cu(Ⅱ). The separation was carried out with a 10mmol/L sodium acetate solution containing 0.8 mmol /L luminol and 2.0 mmol/L HIBA (adjusted to pH 4.8 by HAc solution). The post-capillary reagent was 2.0 mmol/L K3Fe(CN)6 which was adjusted to pH 13.0 by NaOH solution. Under the optimum conditions, the detection limits (S/N=3) for Co(Ⅱ) and Cu(Ⅱ) were 7.5×10-11 mol/L and 7.5×10-9 mol/L, with the linear range of 7.5×10-9 mol/L~1.0×10-6 mol/L and 7.5×10-8 mol/L~5.0×10-5 mol/L, respectively. The RSDs (n=5) for migration time and peak height were 2.2%,2.9% for Co(Ⅱ) ,and 4.2%,4.7% for Cu(Ⅱ),respectively.