Study On Sample Concentration Methods By CICE And FASS Coupled With Preconcentration Technique On-line In CE

Capillary electrophoresis (CE) is a separation technique with high resolution, whichbased on principles of electrophoresis and chromatography. Althought CE is one of thepopular technology in drug analysis, but low detection sensitivity is still an significantrestriction factor. In order to solve this problem, some methods have been established toimprove the detection limit of the CE. However, as one of the concentration method,sweeping is deeply flawed when connect with mass spectrum, which limits thewidespread of concentration methods. At the same time, we also found that the researchof concentration of fat-soluble drugs was relatively less. Therefore, the new sampleconcentration methods were studied on the basis of the reported concentration methods.Two CE on-line concentration methods including CICE-sweeping and samplepre-concentration coupled with FASS were proposed, which were important to expandthe use of CE. The main works in this article were described as follows:1. Established a new CICE-sweeping on-line sample concentration method. Thismethod on the basis of the original CICE-sweeping system by introduction of the plugsof EDTA and borax buffer plug with high conductive. After applied the voltage, themobility chelation boundary was building with the coordination replacement reaction.Pazufloxacin, enoxacin and ciprofloxacin were chosen as analytes objects. By optimizedthe experimental conditions, the results showed that the establishment of this new CEon-line concentration method had a better enrichment effect than traditionalCICE-sweeping method without EDTA plug, the enrichment factor can be increased5-6-fold. The limit of detection (LOD) was ranged from0.08-0.20μg/mL. This newmethod was also applied to the analysis of trace quantitatively fluoroquinoloneantibiotics in rabbit serum, the average recoveries of three analytes were in the range of89-94%.2. Based on the established CICE-sweeping online concentration method above,oxytetracycline, chlorotetracycline and doxycycline were concentrated and separated.After the separation and concentration conditions were optimized, the enrichmentfactors of the three analytes were295,146and185. Subsequently, this on-lineconcentration method was used to detect the trace concentration of oxytetracycline anddoxycycline in human serum. 3. In this paper, sample pre-concentration coupled with FASS was improved, threekinds of fat-soluble vitamins A, D3and K1were selected as analysis objects. Before theexperiment, all the samples were dissolved into CTAB and Brij-35mixed micellarsample matrix. In the process of experiment, borax buffer plug with high conductiveand water plug were injected into capillary firstly. Then the samples distribution intomicelles with positive charge were injected into capillary by using electrokineticinjection system, and separated by MEKC mode. Under the optimization of conditions,zone sharpening with electrokinetic injection and167-435-fold of magnitude improvedin detection sensitivity for model compounds. This method was simple, reliable, notonly greatly simplified the process of sample pre-treatment, but also improved detectionsensitivity and realized the on-line concentration of fat-soluble analytes.