The Study And Application On On-line Pre-concentration Technology In High Capillary Electrophoresis

This article reviewed the development and application on pharmaceutical, food andenvironment analysis by high performance capillary electrophoresis. The techniques ofcombination Sweeping-MEKC, FASI and LVSS were explored and achieved. The contentis described as five chapters:1. A new sweeping-micellar electrokinetic chromatographic （sweeping-MEKC）was used for the simultaneous separation and determination of chlorogenic acid,dehydroandrographolide and chlorphenamine maleate in Jingan capsule. The effect of pHin background solution, concentration of sodium tetraborate, boric acid, sodium dodecylsulfate （SDS）, methanol and injection time on separation efficiency were optimized. Theresult indicated that a best separation of the three organic compounds was obtained on acapillary column （55cm×50μm i. d., effective length42cm） by using the backgroundelectrolyte containing12mmol/L sodium tetraborate,50mmol/L boric acid,50mmol/LSDS and10%（by volume） methanol at pH9.1. Under the optimum conditions,separation of the three organic compounds was performed within14minutes. Thecalibration curves showed good linearity（μg/mL） in the range of2.91～46.56forchlorogenic acid,2.79～44.64for dehydroandrographolide and3.98～63.68forchlorphenamine maleate with detection limits of136μg/L,71μg/L,93μg/L, respectively.The spiked recoveries were93%～103%,96%～110%,96%～110%.2. A new method of sweeping-MEKC was used for the simultaneous separationand determination of acetaminophen, caffeine and chlorphenamine maleate in compoundparacetamol and amantadine hydrochloride capsules. Effect of sodium dodecyl sulfate（SDS） concentration, separation voltage, and injection time of sample, composition andconcentration of background buffer on separation efficiency were optimized. A bestseparation of three compounds was obtained on a capillary column （50cm×50μm i. d.,effective length35cm） by using background buffer containing80mmol/L SDS,20mmol/L NaH₂PO₄and15%acetonitrile at pH2.2. Separation voltage was-20kV andsample injection time was60s. The result indicated that the separation of threecompounds was performed within20min. The calibration curves showed good linearityin the range of2.45～39.17mg/L for chlorphenamine,1.61～25.76mg/L for caffeineand1.58～25.28mg/L for acetaminophen, with detection limits of139μg/L,34μg/L,24μg/L, respectively. The spiked recoveries for acetaminophen, caffeine andchlorphenamine maleate were96%～102%,98%～102%,96%～101%, respectively.3. In this research, the aim was to establish a method for the determination ofchlorphenamine maleate in chlorphenamine maleate tablet by large volume sampleinjection-acetonitrile salts stacking MEKC （LVSI-ASS MEKC）. The determinationcondition containing concentration of acetonitrile and concentration of sodium chloride insample matrix on separation efficiency were optimized. The result indicated that a best separation of chlorphenamine maleate was obtained on an uncoated fused silica capillarycolumn （50cm×50μm i. d., effective length36cm） by using70%（by volume）acetonitrile-200mmol/L sodium chloride（NaCl）in standard and sample matrix. Injectiontime was120s. Under the optimum conditions, chlorphenamine maleate was separatedwithin14min with theoretical plate number of821144. The calibration curve was linearin the range of0.398～6.368mg/L for chlorphenamine maleate with a detection limit of8.95μg/L. The spiked recoveries were in the range of91%～102%. To compare withdetection limit （82.3μg/L） of the normal MEKC method, the sensitivity of the proposedmethod was increased10times （detection limit of8.95μg/L）.4. Field-amplified sample injection and sweeping-micellar electrokineticchromatography （FASI-sweeping-MEKC） was used for the simultaneous separation anddetermination of caffeic acid and chlorogenic acid in honeysuckle. The effect ofexperimental condition, such as concentration of SDS, injection voltage, injection timeratio of water to sample, injection time, composition and concentration of backgroundelectrolyte on separation efficiency were optimized. The background electrolyte was100mmol/L sodium dodecyl sulfate （SDS）-20mmol/L NaH₂PO₄-15%acetonitrile （V/V）（pH2.2）. Sample injection voltage of-10kV and separation voltage of-20kV were used.The sample injection time was15s and water injection time was195s （H=20.0cm）.Under the optimum conditions, the separation of the two organic acids was performedwithin15minutes. The calibration curves showed good linearity in the range of29.4～470.4μg/L for caffeic acid and48.5～776μg/L for chlorogenic acid, with detectionlimits （S/N=3） of1.12μg/L and2.18μg/L, respectively. The spiked recoveries were98%～106%and96%～106%, respectively.5. A new method for simultaneous separation and determination of five phenolicacids-chlorgenic acid, vanillic acid, caffeic acid, gallic acid and protocatechuic acid-Eucommia Ulmoides Oliver （EUO） by Field-amplified sample injection-Capillary zoneelectrophoresis （FASI-CZE） has been proposed. The determination conditions containingpH in background solution, concentration of Na2B4O7and H3BO3, acetonitrile, injectiontime, injection voltage, and separation voltage were optimized. The operating buffer wascomposed of40mmol/L Na2B4O7,40mmol/L H3BO3,10%（by volume） acetonitrile atpH9.5. The UV detection wavelength was215nm, the applied voltage was-10kV,separation voltage was20kV and injection time was480s. The linear ranges of themethod were77.6～1241.6μg/L for chlorgenic acid,2.25～36μg/L for vanillic acid,9.8～156.8μg/L for caffeic acid,11.4～182.4μg/L for gallic acid and7.35～117.6μg/Lfor protocatechuic acid. The recoveries were95%～104%，93%～107%，94%～110%，98%～107%,94%～105%, respectively. And the RSDs of peak area were less than4%and detection limits were9.210μg/L,0.097μg/L,0.350μg/L,0.304μg/L,0.118μg/L forfive phenolic acids, respectively.