Effects of Diethylamine on Capillary Chromatographic Enantioseparation of Some Chiral Analytes Using Polysaccharide Stationary Phases with Pure Polar Solvents as Mobile Phases

摘要

Polysaccharide derivatives are most widely used chiral stationary phases for the HPLC separation of enantiomers in both analytical and preparative scale. Originally, polysac-charide-type stationary phases were developed for normal phase HPLC with mobile phase consisting of hexane and alcohol, usually 2-propanol or ethanol. However, some polar organic solvents, such as methanol, ethanol or acetonitrile have been used effectively on these stationary phases in recent days. Polar organic solvents may offer the advantages of alternative chiral recognition mechanisms, higher solubility of some analytes and having less environmental problems. Though the separation mechanisms for polysaccharide-type stationary phases are not completely known, the contribution of hydrogen bonding and hydrophobic interaction to retention is commonly accepted. A number of studies dealt with the effects of acidic and basic additives to improve the enantioseparation by changing the interaction with derivatized polysaccharide stationary phases. Most of these studies focused on the effects of additives when polysaccharide-type stationary phases were used in normal mode. Hence, the effects of additives in hexane with various kinds of alcohols were well established. However, there has been no report describing the effects of diethylamine as an additive on the enantioseparation in the pure organic mobile phases, such as methanol or acetonitrile. In the present study, the effects of diethylamine as an additive in the pure polar mobile phases were evaluated on the separation of some chiral analytes by capillary chromatoraphy used cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) and amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) as chiral stationary phases.