Characterization and utilization of a novel triflate ionic liquid stationary phase for use in comprehensive two‐dimensional gas chromatography

Abstract

A novel triflate (trifluoromethylsulfonate) ionic liquid (IL) thin film (0.08 microm) stationary phase was implemented for use within the second column of a comprehensive GC x GC configuration. The first column in the configuration had a 5% phenyl/95% dimethyl polysiloxane (DMPS) stationary phase with a 0.4 microm film. The DMPS x IL column configuration was used to separate a mixture of 32 compounds of various chemical functional classes. The GC x GC results for the IL column were compared with a commercially available polar column (with a 0.1 microm PEG stationary phase film) used as the second column instead. Additional studies focused on the rapid and selective separation of four phosphorous-oxygen (P-O) containing compounds from the 32-compound matrix: dimethyl methylphosphonate (DMMP), diethyl methylphosphonate (DEMP), diisopropyl methylphosphonate (DIMP), and triethyl phosphate (TEP). van't Hoff plots (plots of ln k vs. 1/T) demonstrated the difference in retention between the P-O containing compounds (with DMMP reported in detail) and other classes of compounds (i. e., 2-pentanol and n-dodecane as representative) using either the IL column or the commercial PEG column. The selectivity (alpha) of the triflate IL column and the commercially available PEG column were also compared. The IL column provided significantly larger selectivities between DMMP and the other two compounds (2-pentanol and n-dodecane) than the commercial PEG column. The alpha for DMMP relative to n-dodecane was 3.0-fold greater for the triflate IL column, and the alpha for DMMP relative to 2-pentanol was 1.7-fold greater for the triflate IL column than for the PEG column.

Ionic liquid stationary phases for gas chromatography

“…Ragonese et al 102 demonstrated higher resolution in a shorter time between fatty acid methyl esters and alkanes in biodiesel on a commercially available open‐tubular column coated with 1,9‐di(3‐vinylimidazolium)nonane bis (trifluoromethylsulfonyl)imide compared with a similar column coated with poly(ethylene glycol). An increasing use of ionic liquids is found in series coupled columns and comprehensive multidimensional gas chromatography for the separation of model mixtures 103–105, diesel fuel 104, alkyl phosphonates 105, 106, and poly(chlorinated biphenyl) congeners 107. Comprehensive multidimensional techniques employ two or three columns separated by modulation interfaces.…”

A New Dimension in Separation Science: Comprehensive Two‐Dimensional Gas Chromatography

“…The maximization of orthogonality of different stationary-phase combinations has been described using constants of a solvation parameter model, such as the Abraham model. [26] A separation-space evaluation method based on Denaulays triangulation algorithms was proposed by Semard et al, [27] and then further used to optimize the selection of column sets, geometric parameters of the secondary column, Even though non-polar polar column combinations are often stated as the preferred approach for GC GC, nonclassical conditions, that is, polar moderately non-polar column combinations [28] as well as liquid crystalline, [29] ionic liquid, [30] and enantioselective stationary phases, [31][32][33][34] are gaining attention and can lead to high-resolution and grouptype separations. Moreover, Omais and co-workers [35] recently suggested that the non-polar polar column combination is not a necessary condition to achieve large peak distribution in the 2D plane, and non-classical conditions can occasionally provide a large occupation of 2D space.…”

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

“…The difference between the ϕ values (phase ratios) of the columns may explain this difference. The selectivity factors were plotted against the absolute temperature (α vs1/T) to remove the retention time-phase ratio [16]. n-Undecane, citronellol, and acetophenone probes were used to investigate this at 373, 393, 413, and 433 K. Figure 5 shows that the ratio of the selectivity factors of acetophenone and n-undecane (α 1 ) was higher with the LCUT column.…”