Ionic liquid functionalization of semi-packed columns for high-performance gas chromatographic separations

- Two room temperature ionic liquids were immobilized inside semi-packed columns.
- The columns were tested for gas chromatographic separation of complex mixtures.
- These columns displayed symmetrical peaks and rapid separation times.
- The separation efficiency of approximately 2300 plates per meter was obtained.
- Clearly separated peaks of BTEX and naphthalene in gasoline were achieved.

Gas chromatography columns fabricated using microelectromechanical system (MEMS) technology provide a number of clear advantages. However, successful deposition of stationary phases having a wide application range remains an important technical challenge. In this paper, we report, for the first time, on the deposition of room temperature ionic liquids (RTILs)-a versatile class of stationary phases-inside the channels of semi-packed columns (SPCs) for high-performance gas chromatographic separation of complex chemical mixtures. A 1 m long, 240 μm deep, 190 μm wide column comprising an array circular micropillars of 20 μm in diameter and 40 μm post spacing was fabricated using MEMS processes. Two RTILs were immobilized inside these columns using a dynamic coating method, and the columns were tested for separation of three different mixtures: a 15-component mixture of hazardous chemical pollutants, an 8-component mixture of fatty acid methyl esters, and a sample of gasoline. These columns displayed sharp and symmetrical peaks, significant selectivity variation between the two columns, and rapid separation times. The columns yielded high separation efficiencies measured by approximately 2300 plates/m under isothermal conditions. This work highlights the potential of RTILs to be used as excellent stationary phases for SPCs, thereby dramatically expanding the range of complex mixtures that could be analyzed using a micro gas chromatograph.