The Application Investigation Of Capillary Electrophoresis-ion Chromatography

Capillary electrophoresis with contactless conductivity detection is a comparatively new test technology. It has the characteristics of fast detection,high performance, small amount of sample,easy operation and so on. Furthermore,It completely overcame the shortcomings in traditional conductivity detection.Capillary electrophoresis with contactless conductivity detection has a great applied potential and value, moreover it has rapid development in recent years,due to the contactless conductivity detector is simple,easy, low dissipative and so forth. Analytical species not only cover the inorganic ion,but include alcohol, sugar, organic amic, fatty acid, amino acid, protein, small molecular polymer as well. Based on capacitively coupling principle, capacitance coupling contactless conductivity detector in capillary electrophoresis-ion chromatography and its application is studied systematically.At first, capillary electrophoresis with contactless conductivity detector was improved,which includes detection cell and electronic circuit. A new structure of detection cell was designed.And it has small size. detection electrode make of copper foil. in term of electronic circuit, the effect of the feedback resistance, the shielding electrode, the length of electrode lead and the electronic line circuit on the property of C4D detector has been studied. Under the optimal condition: 50V excitation voltage,100kHz excition frequency, 10kV separation voltage, 20mmol/L MES/His buffer solution and electrokinemic injection 5s, the detection limits for the K+ was 0.5nmol/L.Secondly ,the affecting factors of electroosmotic flow by capillary electrophoresis such as type and concentration of ions,concentration of buffer solution,pH value,concentration of addition(CTAB) with contactless conductivity detection were studied. As a result, The affecting of electroosmotic flow from ions type and concentration are small, electroosmotic flow and Square root of concentration of buffer solution are inverse proportion. Regression equation: Ve=-0.1777C1/2+1.578, correlation coefficients r=0.996 , electroosmotic flow and pH value of buffer solution are direct proportion. Regression equation Ve=0.1436pH-0.1105, correlation coefficients r=0.990, electroosmotic flow and voltage are direct proportion. Regression equation: Ve=0.0949E-0.0834,correlation coefficients r=0.998;Electroosmotic flow decrease with increasing the concentration of addition (CTAB) in the concentration region(10~50μmol/L).At last, the determination of salbutamol sulfate in salbutamol sulfate table and salbutamol sulphdte aerosol was accomplished with contactless conductivity detection. Chiefly study the separation of salbutamol sulfate in aqueous mediaand nonaqueousn media,Such as the variety and concentration,pH value of buffer solution, separation voltage etc. were studied. the best analysis conditionswere obtained. The buffer system of 15mmol/L lactic acid and 10kV of separation potential meet the best. Under the chosen condition ,The linear relationship ranged from 9.60 to 48.00μg/mL ( r= 0. 995) , the limit of detection (LOD) reached 1.92μg/ml (S /N = 3).