[Uncharged monolithic capillary column modified with an anionic surfactant in electrochromatography].

A monolithic capillary column was obtained by in-situ co-polymerization of butyl methacrylate with ethylene dimethacrylate. A mode of capillary electrochromatography (CEC) based on the dynamic adsorption of long chain sodium dodecyl sulfate(SDS) on the monolithic stationary phases was developed. Effects of SDS concentration and concentration of acetonitrile in mobile phase on the electroosmotic flow(EOF) of the column and the plate height on the electroosmotic velocity were investigated. Efficiency of monolithic capillary column with higher than 140,000 plates per meter for neutral aromatic compounds were obtained, and the relative standard deviations observed for dead time(t0) and retention times of neutral solutes were about 0.22% and less than 0.56% for ten consecutive runs, respectively.

[The effect of temperature on the enantiomeric resolutions on albumin and beta-cyclodextrin chiral stationary phases].

The effect of column temperature on enantiomeric resolutions of tryptophan, warfarin and ketoprofen was investigated on bovine and human serum albumin (BSA and HSA) stationary phases, which were synthesized with s-triazine as the activator. It was observed that the entropy change made a great contribution to the separation of those enantiomers on albumin chiral stationary phases. The column temperature for the maximal resolution of tryptophan on the BSA stationary phase prepared by this method was about 35 degrees C, which was not 24 degrees C as reported for the BSA stationary phase synthesized with glutaric dialdehyde as the activator. This results may come from the different conformation of the immobilized BSA and HSA due to the different coupling methods used. On the other hand, it was indicated that the resolution of enantiomers on beta-CD chiral stationary phase was mainly contributed from the change of enthalpy, which means the resolution of chiral solutes on albumin and beta-CD stationary phases has different thermodynamic behaviors.

[Chiral separation by capillary electrochromatography on stationary phase adsorbed with protein].

A method based on the adsorption of bovine serum albumin (BSA) on the strong anion-exchange packing (SAX) was applied to prepare chiral stationary phases for capillary electrochromatography. It was found that the electroosmotic mobility only decreased 26.3% when the BSA was adsorbed. The run-to-run reproducibilities of void time and the migration times of D- and L-tryptophan enantiomers were rather good with the relative standard deviation (RSD) values of 0.90%, 0.87% and 0.96%, respectively, when mobile phase containing 7% (volume fraction) acetonitrile. The merit of this system is that the direction of electroosmotic flow is still from cathode to anode, preferable to separate acidic enantiomers. Four anionic enantiomers, tryptophan, ketoprofen, fenoprofen and warfarin, as well as the neutral enantiomers of benzoin were successfully resolved. In order to reduce the analysis time, n-hexanoic acid was added to the mobile phase as a competitive agent. The effect of acetonitrile volume fraction on the resolution of enantiomers was also investigated.

[Preparation and evaluation of phosphatidylcholine coated on silica as the biomembrane stationary phase].

The method of reverse phase evaporation is used to coat phosphatidylcholine(PC) directly on the surface of silica, which is used as biomembrane chromatographic solid phase to study the interactions between drugs and biomembrane. It was observed that the solid phase coated phosphatidylcholine had a good stability at 20 degrees C-30 degrees C, and the stability would be improved by the presence of appropriate amount of cholesterol in phosphatidylcholine. The content of cholesterol in phosphatidylcholine, the nature of buffer, the concentration of salt in buffer and the pH of mobile phase could all affect chromatographic retention of drugs on the prepared biomembrane column. Six compounds, polyethylene glycol, mannitol, salicylic acid, warfarin, hydrocortisone, and cortisone have been tested. The biomembrane chromatographic stationary phase coated PC with silica as matrices can be simply prepared and it is possible to simulate the human's physiological environment by the biomembrane chromatographic system, so it is a useful method to study drug absorption and distribution in human body.

[Immobilized Ni(2+)-IDA metal chelating affinity membrane chromatography for purification of commercial human serum albumin].

Further purification of commercial human serum albumin was studied on immobilized Ni(2+)-IDA composite membrane cartridge. Effect of pH on HSA binding capacity was examined. A lot of impurities in the commercial HSA had been removed by a single step purification with a recovery of more than 85% of the protein bound on membrane cartridge. The purified HSA was of comparable purity of that from Sigma company analyzed by capillary electrophoresis. The nickel ion retained in the protein solution could be removed efficiently with the N, N, N'-tris (carboxymethyl) ethylenediamine chelating membrane cartridge.

[The preliminary study on the open tubular capillary affinity liquid chromatography].

A novel mode of affinity chromatography based on the open tubular column (OTAC) is presented in this paper. The OTAC column was prepared by coating a layer of Cibacron Blue F3GA onto the inner surface of capillary column with 50 microns inner diameter. The affinity chromatography experiment was performed on a capillary electrophoresis instrument by using its pressure system as driving force. The bovine serum albumin (BSA) and lysozyme (Lys) were successfully separated with step gradient elution. The relative standard deviation (RSD) for 10 consecutive runs for the elution time of lysozyme was less than 0.1%, and those for its peak area and peak height were 4.3% and 3.7% respectively. The good linear relationships of the amount of the injected lysozyme versus its peak area and peak height were observed with correlation coefficients of 0.9946 and 0.9988 respectively in the range from 8.6 ng to 28.7 ng.