Study On On-line Preconcentration Technology In Capillary Electrophoresis And Its Application To Pharmaceutical Analysis

In this thesis, the development and application of CE on-line preconcentration techniques in pharmaceutical analysis were reviewed. The combination of electrostacking-large volume sample stacking and sweeping micellar electrokinetic chromatography technique was studied systemly. Meanwhile, the mechanism and principal of on-line preconcentration techniques were discussed. The major content is described as follows:1. Sweeping micellar electrokinetic chromatography (Sweeping-MEKC) was used for the simultaneous separation and determination of Ferulic Acid and Protocatechuic Aldehyde. The operating buffer was composed of 20 mmol/L NaH2PO4, 140 mmol/L SDS, and 16% (by volume) methanol at pH 2.2 with a constant temperature of 25℃and applied voltage of -20 kV, the detection wavelength was set at 316 nm, sample injection time was 100 s, sample injection height was 16 cm. Under the optimum conditions, the determination time was within 19 minutes with relative standard deviation (RSDs) of peak area less than 5%. The linear ranges of the method were 0.72~23μg/mL and 0.67~21.4μg/mL, the detection limits (S/N=3) of Ferulic Acid and Protocatechuic Aldehyde were 56μg/L and 35μg/L, the recoveries were 94～108% and 91～106%.2. Large volume sample stacking-Sweeping micellar electrokinetic chromatography (LVSS-sweeping-MEKC) was used for the simultaneous separation and determination of salidroside, caffeic acid and gallic acid in Rhodiola L. The operating buffer was composed of 20 mmol/L Na2B4O7, 80 mmol/L SDS and 10% (by volume) ACN at pH 9.70 with a constant temperature of 25℃. The UV detection wavelength was 213 nm, the reverse voltage was -8 kV, separation voltage was 20 kV and injection time was 120 s. The linear ranges of the method were 13.1～49.6μg/L for salidroside, 1.0～15.7μg/L for caffeic acid, 1.1～18.2μg/L for gallic acid. The recoveries were 95～106%, 98～112%, 91～108%, respectively. The RSDs of peak area were less than 4%. And detection limits (S/N=3) were 194μg/L, 28μg/L, 29μg/L for salidroside, caffeic acid and gallic acid , respectively.3. Electrostacking-Large Volume Sample Injection-Sweeping micellar electrokinetic chromatography was used for the simultaneous separation and determination of two alkaloids– matrine and sophoridine - in sophora flavescens. The operating buffer was composed of 20 mmol/L NaH2PO4, 0.8 mmol/L CTAB, 100 mmol/L Tris, and 10% (by volume) isopropanol at pH 8.90 with a constant temperature of 25℃. The UV detection wavelength was set at 211 nm.The applied voltage was 10 kV, and separation voltage was -20 kV and injection time was 480 s. Under the optimal conditions, the calibration curves were linear in the range of 46～736μg/L for matrine and 50～792μg/L for sophoridine, with detection limits (S/N=3) of 2.41μg/L and 1.11μg/L, respectively. The spiked recoveries were in the range of 93-109% and 89-103%, respectively,with RSDs of less than 5%.4. Electrostacking-Large Volume Sample Stacking-Sweeping micellar electrokinetic chromatography was used for the simultaneous separation and determination of four organic acids - isoferulic acid, cinnamic acid, ferulic acid and vanillic acid - in Picrorhiza Scrophulariiflora Pennell. The operating buffer was composed of 40 mmol/L Na2B4O7, 80 mmol/L SDS and 10% (by volume) methanol at pH 9.40 with a constant temperature of 25℃. The UV detection wavelength was 214 nm, the applied voltage was -10 kV, separation voltage was 20 kV and injection time was 450 s. The linear ranges of the method were 16～543μg/L for Isforerulic acid, 16～518μg/L for Cinnamic acid, 18～589μg/L for Ferulic acid and 14～161μg/L for Vanillic acid. The recoveries were 93～111%, 102～107%, 96～108%, 103～108%, respectively. And the RSDs of peak area were less than 4% and detection limits (S/N=3) were 618 ng/L, 148 ng/L, 368 ng/L, 76 ng/L for four organic acids respectively.