Evaluation of new ionic liquids as high stability selective stationary phases in gas chromatography

Abstract

Two ionic liquids (ILs), namely (S,S)-1-butyl-3-(2'-hydroxy-cyclohexyl)-3H-imidazol-1-ium tetrafluoroborate and (S,S)-1-butyl-3-(2'-acetyl-cyclohexyl)-3H-imidazol-1-ium tetrafluoroborate have been employed as stationary phases in capillary gas chromatography. These new phases exhibit a column efficiency of 1,600 and 2,100 plates m(-1) for IL 1 and IL 2, respectively, a wide operating temperature range and good thermal stability (bleeding temperature of 250 °C for IL 1 and 160 °C for IL 2). Inverse gas chromatography (GC) analyses were used to study the solvation properties of these ILs through a linear solvation energy model. The application of these ILs as new GC stationary phases was studied. These stationary phases exhibited unique selectivity for many organic substances, such as alkanes, ketones, esters, and aromatic compounds. The efficient separation of several mixtures containing compounds of different polarities and the good separation of fatty acid methyl esters (FAMEs) and cis/trans isomers indicate that these ILs may be applicable as a new type of GC stationary phases.

Ionic liquid thermal stabilities: decomposition mechanisms and analysis tools

“…These specialised techniques can contribute to the exact unravelling of the thermal degradation pathways, mainly by identification of the degradation products. Thus, investigation of thermal stabilities has already been performed by coating the ionic liquid in fused silica capillaries which are heated and monitored by FID or mass spectrometry (MS), 30,31,83 as well as by pyrolysis-GC, 72,99 headspace GC/MS, 10 pyrolysis-MS, 32 TGA-MS, 9,61,65,100 and thermal desorption mass spectroscopy (TDMS). 35 Although TGA-MS is a very powerful method, it should be noted that the absence of molecular ions does not necessarily exclude vaporisation, since the transfer of TGA to MS and pressure differences herein involved hinder the detection.…”

“…solvents for organic reactions at high temperature, [6][7][8] solvents for cellulose, [9][10][11] thermal energy storage (TES) 12,13 and heat-transfer fluids (HTFs), [14][15][16][17][18] high-temperature lubricants, 19,20 propellants, 21,22 curing of ionogels 23,24 and in an analytical apparatus, such as matrices in matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF) [25][26][27] or as a stationary phase in gas chromatography. [28][29][30][31] In order to determine the thermal behaviour and the temperatures which allow for a correct and safe application, it is important to study the behaviour of ionic liquids at elevated temperatures and to understand the degradation mechanisms.…”

Capillary Gas Chromatographic Separation of Carboxylic Acids Using an Acidic Water Stationary Phase

“…However, the creation of novel stationary phases that can provide more thermal stability and/or greater analyte selectivity has increasingly been a focus of research in this area. For instance, a range of novel GC stationary phase coatings have been explored, which possess very useful separation characteristics, such as those composed of ionic liquids [11][12][13][14], metal-organic frameworks [15,16], and dithienyl benzothiadiazoles [17].…”

Evaluation of ionic liquid stationary phases for one dimensional gas chromatography–mass spectrometry and comprehensive two dimensional gas chromatographic analyses of fatty acids in marine biota

“…Polar ionic liquid phases were used for the analysis of fatty acid methyl esters [32][33][34], and their potential for the separation of eicosenoic acid (C20:1) isomers [35] and octadecenoic acid (C18:1) and octadecadienoic acid (C18:2) isomers [36] was demonstrated. For these applications, flame ionization detection (FID) was used.…”