Katsunori Watabe

Liquid Crystals as the stationary phae in Gas Chromatography : IV. Evaluation of the combination of a separation column and an electric field liquid crystal column

Abstract The electric field-liquid crystal (EFLC) adsorption column described previously has been made shorter and located behind the glass capillary separation column, and the effects on the adsorption capacity, the reproducibility of adsorption, the utility of diffeernt stationary phases for the separation column and temperature such as capability of selection column have been investigated. Several advantages, temperature programming the separation column, were found. The combination of temperature programmed high-performance separation column with a 4,4′-azoxydianisole EFLC column was applied successfully to the determination of aromatic hydrocarbons spiked in a vegetable oil fraction.

Liquid crystals as the stationary phase in gas chromatography: Adsorption phenomena caused by an electric field applied across the column

Abstract An investigation of the direct current electric field effect on capillary column gas chromatography, in which liquid crystals were used as the stationary phase, is described. When the electric field was applied across the column axis, the peak size was reduced, to an extent that depended on the configuration of the solute molecule, the field strength and the stationary phase employed. When the field strength was increased the amount adsorbed also increased. At every injection, the amount of sample adsorbed was constant, i.e. independent of sample size. This phenomenon was successfully exploited in qualitative and quantitative experiments.

Gas chromatographic resolution of optical isomers on two new diamide stationary phases, N-Lauroyl-l-valine tert.- octylamide and N-dicosanoyl-l-leucine tert-octylamide

Abstract Two novel diamide chiral stationary phases are described: N-lauroyl- l -valine tert-octylamide (I) and N-docosanoyl- l -leucine tert-octylamide (II). Their chromatographic behaviour in stailess-stell capillary columns and on whisker-walled glass capillary columns is reported. The phases have been employeed at a miximum column temperature of 180°C for II, showing good stereoselectivity for N-trifluoroacetyl (N-TFA) esters of α- and γ-amino acids, a N-TFA-dipeptide ester and N-TFA-O-pivaloyl aminoalcohols.

Liquid crystals as stationary phases in gas chromatography : V. Adsorption behaviour of aliphatic alcohols and their esters on an electric field liquid crystal column

Abstract Previously various aspects of adsorption phenomena in electric field liquid crystal (EF-LC) columns were investigated. In this study, to establish the mechanism of the phenomenon, the amounts of C 4 and C 5 aliphatic alcohols and esters adsorbed were measured on three types of EF-LC columns, and the effects of the dielectric constants and the carbon skeleton structures of the solutes on the amounts adsorbed were determined. It was found that the amounts of isomers such as pentanols and butanols adsorbed were different from each other, although these isomers have similar dielectric constants. It was concluded that the adsorption was influenced not only by the dielectric constant, but also by the structure of the carbon skeleton. The equation proposed previously for the relationship between the field strength and the extent of adsorption was modified by introducing a structural term, f s . Subsequently, the dielectric constants of esters were calculated from the equation by using the f s values of the corresponding alcohols, and were compared with those found in the literature. The differences were within 10%.

Liquid crystals as the stationary phase in gas chromatography : VI. Application of the adsorption phenomenon to the analysis of overlapping peaks

Abstract A method which provides a simple means for the determination of individual compounds which gave overlapping peaks on a gas chromatogram is described. It utilizes the adsorption property of the electric field applied liquid crystal column previously reported: under a constant electric field, the amounts of compounds adsorbed are independent of the amounts injected. The sample volume vs. response curves exhibit inflection points, theoretically predicted. Similar curves obtained experimentally for binary and ternary overlapping systems were exactly as predicted. Also, the amounts of individual compounds determined experimentally were in good agreement with those calculated from the theoretical curves.