Fast chiral separations using packed capillary columns and near-critical fluid carbon dioxide mobile phase

Abstract

In this study, fast chiral separations were demonstrated using near‐critical carbon dioxide as mobile phase. Most separations were carried out in less than 1 min at 30°C using 12–15 cm capillary columns packed with 5 μm porous (300 Å) silica particles deactivated with 3‐cyanopropyldimethylchlorosilane and encapsulated with cyclodextrin‐substituted polymethylsiloxane. The fastest separation was accomplished in 36 s. Effects of surface deactivation, temperature, pressure, and restrictor internal diameter on performance were investigated. Results show that 3‐cyanopropyldimethylchlorosilane was a better deactivation reagent than polymethylhydrosiloxane. Near‐critical fluid chromatography, which is classified along with supercritical fluid chromatography (SFC) in this paper, is more suitable for fast separation of enantiomers than open tubular column gas chromatography (GC). SFC can be performed under low temperatures and high pressures, which allow high selectivity and high speed. Temperature had a significant effect on retention factor, selectivity, resolution, and resolution per unit time. Pressure had little effect on selectivity but had a considerable effect on retention factor and resolution. Finally, dimensions of the linear restrictor (in other words, the pressure at the end of the column) had a significant influence on speed and resolution. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 454–461, 2000

Columns in analytical‐scale supercritical fluid chromatography: From traditional to unconventional chemistries

“…Due to the different selectivity of each stationary phase, the applications were extended from the separations of nonpolar molecules such as polymers, PAH, and aliphatic hydrocarbons to pharmaceutical analysis, lipidomics, and environmental analyses of pesticides. The packed capillaries were successfully used in the analysis of organometals on the C18 bonded stationary phase [80][81][82][83]. They were also adapted for the analysis of biological samples containing androstenone [84] and toxicological samples [85,86], as they are advantageous due to the low sample consumption.…”

Chiral Separations

“…The chiral recognition mechanism is also discussed. Fast chiral separations using silica gel encapsulated with cyclodextrin-substituted polymethylsiloxane packed capillary columns and near-critical fluid carbon dioxide mobile phase were reported by Wu et al (70). The fastest separation was achieved in 36 s. Packed capillary -CD columns were prepared and evaluated in SFC for the effect of pore size on the speed of chiral separations (71).…”