Capillary column coated with geminal ionic liquids as stationary phases for gas chromatographic separation

Abstract

Summary. Four geminal ionic liquids (GILs), namely, 1,4-bis(1,1′-butyl-3,3′-methylene-imidazolium)-benzene bis[(trifluoromethyl)sulfonyl]imide (BBMIB-NTf2), 1,4-bis(1,1′-butyl-3,3′-methylene-imidazolium)-benzene tetrafluoroborate (BBMIB-BF4), 1,4-bis(1,1′-butyl-3,3′-methylene-imidazolium)-benzene hexafluophosphate (BBMIB-PF6), and 1,4-bis(1,1′-methyl-3,3′-methylene-imidazolium)-benzene bis[(trifluoromethyl) sulfonyl]imide (BMMIB-NTf2), were synthesized. They were statically coated onto the inner walls of fused-silica capillary columns and used as stationary phases for gas chromatography. The evaluation of BBMIB-NTf2, BBMIB-BF4, BBMIB-PF6, and BMMIB-NTf2 as stationary phases is reported here for the first time. These new stationary phases exhibit efficiencies of at least 2.3 × 10 3 plates per meter. Abraham solvation parameter model was used to evaluate the solvation characteristics. The system constants indicated that the dipolarity/polarizability and the hydrogen-bond basicity play a major role among five molecular interactions between stationary phases and solute molecules. A fundamental understanding into the solvation characteristics of these GILs can be used as a guide to choosing the appropriate geminal ionic liquids for specific applications in various fields. The chromatographic separation performance was evaluated by a Grob test mixture, n-alkanes, alcohols, and aromatic isomers. Furthermore, the thermal stability was tested. The present results demonstrate that these geminal ionic liquids stationary phases possess excellent chromatographic separation performance and good thermal stability (at least up to 270 °C) and may be applicable as gas chromatography stationary phases for more application.

Advances of Ionic Liquids in Analytical Chemistry

“…124 Jiang et al investigated the separation performance and solvation properties of four different geminal ILs with p-xylene as the linker chain. 125 These ILs exhibited excellent separation performance for aromatic positional isomers. In addition, the ILs containing [NTf 2 − ] anions possessed better selectivity for alcohols and aromatic positional isomers compared to ILs comprised of [BF 4 − ] and [PF 6 − ] anions.…”

“…Several physicochemical properties including viscosity, density, and thermal stability of branched-chain ILs were also reported . Jiang et al investigated the separation performance and solvation properties of four different geminal ILs with p -xylene as the linker chain . These ILs exhibited excellent separation performance for aromatic positional isomers.…”

Preparation and evaluation of a novel bonded imidazolium ionic liquid as stationary phase for gas chromatography

“…ILs have attracted major attention of researchers owing to their unique properties, for instance, low melting point, excellent solubility of organics, good thermal stability, almost negligible vapor pressure and electrical conductivity . Up to now, ILs have gained broad applications in almost all chemical fields, such as catalysis , organic synthesis , electrochemistry , extraction , electrochromatography , HPLC , GC , etc.…”

“…reported that four geminal ionic liquids, which were consisted of imidazolium‐based dications and relatively inert anions, were synthesized and statically coated onto the capillary columns as stationary phases for GC. Further experimental results revealed that these columns possess good chromatographic separation performance and thermal stability . According to Sun's research, γ‐chloropropyl‐polysiloxane was firstly synthesized and it was reacted with methylimidazolium.…”