Simultaneous separation and analysis of camptothecin alkaloids in real samples by large-volume sample stacking in capillary electrophoresis

摘要

Large-volume sample stacking (LVSS) is commonly used as an effective online preconcentration method in capillary zone electrophoresis (CZE). In this paper, the method LVSS combined with CZE has been proposed to analyze camptothecin alkaloids. Optimum separation can be achieved in the following conditions: pH9.0; 25mm borate buffer containing 20mm sulfobutylether--cyclodextrin and 20mm ionic liquid 1-ethyl-3-methyllimidazole l-lactate; applied voltage 20kV; and capillary temperature 25 degrees C. The LVSS was optimized as hydrodynamic injection 4s at 5.0psi and the polarity switching time was 0.17min. Under the above conditions, the analytes could be separated completely in 20min and the detector response was increased compared with conventional hydrodynamic injection. The limits of detection were between 0.20 and 0.78g/L. A good linearity was obtained with correlation coefficients from 0.9991 to 0.9997. The recoveries ranged from 97.72 to 103.2% and the results demonstrated excellent accuracy. In terms of the migration time and peak area, the experiment was reproducible. The experimental results indicated that baseline separation can be obtained and this method is suitable for the quantitative determination of camptothecin alkaloids in real samples.