Chenfu Zhu

Chiral separation of pemoline enantiomers by cyclodextrin-modified micellar capillary chromatography

Micellar electrokinetic chromatography (MEKC) was successfully applied to the chiral separation with the addition of cyclodextrins (CDs) as chiral selector to running buffer. Chiral separation depended on the type of CDs. Mono-3-O-phenylcarbamoyl-beta-CD was effective for the chiral separation of pemoline. We investigated the type and concentration of CD and other parameters such as buffer pH, the concentration of SDS and the effect of organic modifier. The conditions for enantiomeric separation of pemoline were as follows: 40 mmol/l borate buffer at pH 9.0 with 40 mmol/l SDS, 20 mmol/l mono-3-O-phenylcarbamoyl-beta-CD and 10% 2-propanol. Baseline separation (Rs=2.21) of pemoline can be achieved.

The production of electrochromatography capillary columns using gas pressure powered dry-packing method

Abstract This paper introduces a dry-packing method of producing packed capillaries for using in capillary electrochromatography (CEC) or microbore HPLC. Several C18 packing materials with different particle size are studied. We compared the two methods of dry-packing and slurry-packing. The former yields analogous or better efficiency with a simpler apparatus using a shorter packing time. Besides, the columns are very stable and no loss in efficiency was found after using a column continuously for over one month. By experiments, we found that air bubbles easily occurred in columns whose inlet frit was fabricated by gluing particles differing from the packing particles. No air bubbles were generated with frits prepared by locally sintering a narrow band of the reversed-phase packing by means of a heating filament, while flushing the column with water.

Effect of Different Substituted Position of Phenylcarbamoyl‐β‐CD on the Enantioseparation of Drugs by Capillary Electrophoresis

ABSTRACT A number of acidic and basic chiral drugs such as β‐agonists, β‐antagonists, and phenylethylamines were separated by capillary electrophoresis with mono‐3‐O‐phenylcarbamoyl‐β‐CD and mono‐6‐O‐phenylcarbamoyl‐β‐CD. The effects of the CD type and concentration and the pH of the background electrolyte on the resolution of the drugs had been studied. The substituted position has a significant effect on the separation of chiral drugs and is therefore an important factor in the optimization of chiral resolution. Accordingly, a proper description of derived cyclodextrins should include substituted position.