The Application Of On-line Concentration To Determinate The Preservatives And The Study Of The Double Peak Phenomena

As a classical electrophoresis technique that was combined with micro-column separation, capillary electrophoresis attracted most of the analytical researchers because of its celerity and high performance after appearing. However, CE is restrained by low concentration sensitivity, in a way on-line concentration techniques is s satisfactory method that could discuss this question; the other question is the double peak phenomenon, which maybe give some wrong chromatography information .In this thesis, there are four chapters, the development of CE and on line concentration .the application of on-line concentration techniques and the double peak phenomenon. Chapter one: it is an introduction of the basic theory of capillary electrophoresis and on-line concentration technique and the double peak phenomenon. Chapter two: Determining method of trace salicylic acid in cosmetic was established by a micelle capillary electrophoresis on-line sweeping concentration technique. The effect of pH in background solution, the concentration of SDS, injection time, was investigated .The result shown that the sample was analyzed with 15mmoL/L phosphate+30mmoL/L SDS (pH=7.00) as the running buffer UV detector, wavelength 214nm; run voltage 18KV. This condition allowed up to 700-fold concentration of the salicylic acid .The results showing that the method is precise, simple and cost-effective.. Chapter three: A new micelle capillary electrophoresis method with on-line sweeping concentration for the determination of preservatives in the foods. The effect of pH in background solution, the concentration of SDS, injection time, was investigated. Under the optimal conditions, the sample directly injected into the column after it was simple pretreated, this condition allowed up to 150-fold concentration of the benzoic acid. The results shows that the method could be successfully to determinate the trace in the real sample. Chapter four: The double peak phenomenon in micellar electrokinetic capillary chromatography was studied with sodium dodecylsulfate as the pseudo stationary phase. The effect of pH value ,The concentration of H3BO3,SDS concentration,injection time and operation voltage on the double peak of benzoic acid,p-Aminobenzoic acid and salicylic acid...