Investigations of potential ionic liquid phases for chromatographic processes using spectroscopic and thermal techniques

The thermal degradation of ionic liquids 1-octyl-3-methyl imidazolium trifluoromethanesulfonate ([OMIM][TfO]) and 1-octyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][Tf2N]) were investigated using spectroscopic and thermal techniques to predict gas chromatographic phase stability. For differential scanning calorimetry, lowering the heating rate from 10 to 2 degrees C/min decreased the decomposition temperature of the ionic liquids ti 23 degrees C for [OMIM][TfO] and ti 13 degrees C for [OMIM][Tf2N]. In addition, lowering the heating rate gave better resolution and showed anion thermal decomposition occurred several degrees before cation decomposition for the ionic liquids. Experimental measurements showed that decomposition of the ionic liquids was indicated at lower temperatures when using spectroscopic methods compared to thermal scanning methods. Total synchronous fluorescence spectroscopy was used to monitor the formation of ionic liquid degradation products during thermal stress experiments. Decomposition temperatures determined by differential scanning calorimetry were approximately 140 degrees C higher compared to measurements by fluorescence spectroscopy. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The thermal degradation behavior of two ionic liquids was investigated using spectroscopic and thermal techniques to predict their phase stability in gas chromatography. The study found that lowering the heating rate decreased the decomposition temperature of the ionic liquids, and spectroscopic methods indicated lower decomposition temperatures compared to thermal scanning methods.