Stationary Phases For Capillary Gas Chromatography Research Articles

Evaluation of the Effect of Citronellol Group on Functionalized Mesogenic Materials by Capillary GC

In this paper, the effects of functionalization with terpenes on two new liquid-crystalline stationary phases for gas chromatography (GC) are described. Citronellol was used as the terminal group in the first material, and tetrahydrogeraniol was used with a second material. Inverse GC showed that the new materials have wide liquid-crystalline ranges (mesophases), 371–500 and 395–501 K, respectively. Moreover, they show good thermal stability up to 523 K and good potential as stationary phases for capillary GC. To clarify the effects of the liquid crystal structures and functional groups on retention and separation, the chromatographic behaviors of the two stationary phases were compared by eluting alkylbenzenes, polycyclic aromatic hydrocarbons, aromatic compounds, and terpenoids. The selectivities for a wide range of analytes achieved using the citronellol column were significantly better than those obtained using the tetrahydrogeraniol column. The columns showed different retention behaviors and fine resolutions for some of the main constituents of essential oils. Introduction of the double bond of citronellol greatly improved the polarization interactions involved in the shape recognition of the liquid-crystalline state for isomers. The new citronellol liquid-crystalline stationary phase, therefore, has a high affinity for natural compounds.

Preparation and characteristics of two novel calix[4]arene polysiloxane stationary phases for capillary gas chromatography

Two novel calix[4]arene derivatives, 5-1′,1′-dimethylundecyloxyphenylmethyl-11,17,23-tris-1″, 1″-dimethylethyl- 25,26,27,28-tetrabenzyloxycalix[4]arene polysiloxane (C[4]TB-PSO) and 5-1′,1′-dimethylundecyloxyphenyl- methyl-11,17,23-tris-1″,1″-dimethylethyl- 25,26,27,28-tetraethoxycarbonylmethyloxycalix[4]arene polysiloxane (C[4]TECM-PSO), were synthesized and used as stationary phases in capillary gas chromatography. The new phases demonstrated high column efficiency, a wide operating temperature range, high thermal stability, medium polarity and excellent selectivity towards alcohol isomers and positional isomers of aromatic compounds. The selectivity mechanism for positional isomer compounds was investigated by the measurements of thermodynamic parameters, ΔH, ΔS and ΔG. The inclusion properties of the calix[4]arenes are discussed.