| Chemiluminescence(CL) analysis has developed in China since the end of 1970 s. It has been rapid development because of its advantages of high sensitivity, low cost, easy to operate, easy to achieve automation and rapid detection. The research and development of new chemiluminescence system is also one of the hot spots in the field of Hygienic Chemistry. Chemiluminescence does not require an external light source, but certain substances in the reaction system absorbed in response to release of chemical energy and is excited. The energy is released in the form of light radiation and produced by the excited state to return to the ground state, which can avoid the influence of ambient light. Its application is limited because of the poor selectivity. Chemiluminescence is often used in combined with high selectivity technology such as high performance liquid chromatography, capillary electrophoresis and so on. Compared with high performance liquid chromatography, capillary electrophoresis has advantages in separation efficiency, analysis speed, consumption cost and sample consumption.In the previous research work, it was found that the Ag(?) complex and the Ni(?) complex can react with Luminol and produce a stable chemiluminescence signal under the alkaline condition. Respectively, the Ag(?) complex – luminol chemiluminescence system and Ni(?) complex – luminol chemiluminescence system coupled with high efficiency separation characteristics of capillary electrophoresis for the separation of substances in human urine was established. The method is simple and does not require complex sample pretreatment procedures, and the results are accurate and reliable. PART 1 Detection of folic acid by capillary electrophoresis analysiscombined with luminol–Ag(?) complex chemiluminescenceObjective: To establish a new method of capillary electrophoresis coupled with chemiluminescence for the detection of folic acid.Method: Under alkaline conditions, Ag(?)–luminol chemiluminescence system has stable signal and folic acid can obvious suppress the CL intensity of the system. The CL intensity exhibits good linearity to the analyte concentration within a certain range. The separation conditions and the light emitting conditions were optimized. The linear range of folic acid was determined and the standard curve was drawn. The technique was used to determine folic acid in tablets samples and human urine under optimal conditions.Results: The linear range of folic acid was measured 5~150 mg/L under the optimized conditions. The results of the linear regression equation are as follows: ?I = 3.5051 C + 9.916, r = 0.9953. The limit of detection of folic acid was estimated as 2.31 mg/L. And 11 injections of a standard of 80 mg/L of folic acid was investigated. The relative standard deviation was 2.8%. The recoveries of the standard addition of tablets and human urine ranged from 81.30% to 114.13% and from 81.98% to 105.74%, respectively.Conclusion: Capillary electrophoresis chemiluminescence method is simple and rapid, accurate and reliable for the determination of folic acid in tablets and human urine. PART 2 Detection of 8-hydroxy-2'-deoxyguanosine, homovanillic acid and5-hydroxyindol acetic acid by capillary electrophoresis analysiscombined with luminol–Ni(?) complex chemiluminescenceObjective: To establish a new method of capillary electrophoresis coupled with chemiluminescence for the detection of 8-hydroxy-2'-deoxyguanosine, homovanillic acid and 5-hydroxyindol acetic acid.Method: Under alkaline conditions, Ni(?)–luminol chemiluminescence system has stable signal and 8-hydroxy-2'-deoxyguanosine, homovanillic acid and 5-hydroxyindol acetic acid can obvious suppress the CL intensity of the system. The CL intensity exhibits good linearity to the analyte concentration within a certain range. The separation conditions and the light emitting conditions were optimized. The linear range of 8-hydroxy-2'-deoxyguanosine, homovanillic acid and 5-hydroxyindol acetic acid were determined and the standard curves were drawn. The technique was used to determine 8-hydroxy-2'-deoxyguanosine, homovanillic acid and 5-hydroxyindol acetic acid in human urine under optimal conditions.Results: The linear range of 8-hydroxy-2'-deoxyguanosine was measured 0.2~10 mg/L under the optimized conditions. The results of the linear regression equation are as follows: ?I= 16.455 C + 14.413, r = 0.9955. The limit of detection of 8-hydroxy-2'-deoxyguanosine was estimated as 0.2 mg/L. And 7 injections of a standard of 4 mg/L of 8-hydroxy-2'-deoxyguanosine was investigated. The relative standard deviation was 1.5%. The recoveries of the standard addition of human urine ranged from 94.73% to 105.22%.The linear range of homovanillic acid was measured 0.08~10 mg/L under the optimized conditions. The results of the linear regression equation are as follows: ?I= 29.77 C + 4.777, r = 0.9998. The limit of detection of homovanillic acid was estimated as 0.08 mg/L. And 7 injections of a standard of 4 mg/L of homovanillic acid was investigated. The relative standard deviation was 1.7%. The recoveries of the standard addition of human urine ranged from 86.96% to 106.37%.The linear range of 5-hydroxyindol acetic acid was measured 0.1~5 mg/L under the optimized conditions. The results of the linear regression equation are as follows: ?I= 30.827 C + 7.0585, r = 0.9978. The limit of detection of 5-hydroxyindol acetic acid was estimated as 0.1 mg/L. And 7 injections of a standard of 4 mg/L of 5-hydroxyindol acetic acid was investigated. The relative standard deviation was 1.96%. The recoveries of the standard addition of human urine ranged from 84.88% to 103.81%.Conclusion: Capillary electrophoresis chemiluminescence method is simple and rapid, accurate and reliable for the determination of 8-hydroxy-2'-deoxyguanosine, homovanillic acid and 5-hydroxyindol acetic acid in human urine. |
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