Comparison of gas chromatography detection limits and relative responses of common alternative fluorocarbons using electron capture, atomic emission, and mass spectrometry detection

On-line trace monitoring of volatile halogenated compounds in air by improved thermal desorption-gas chromatography-mass spectrometry

Volatile halogenated compounds (VHCs) are important industrial chemicals and play a crucial role in potential stratospheric ozone-depletion and global warming. Profiling of VHCs is of great significance but replete with challenges due to the species' richness and diversity. In this study, we developed a novel method employing water removal mode combined with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for on-line measurement of VHCs at the ultratrace level. By removing water with Nafion dryer tandem cold trap device, VHCs could achieve better separation and identification, and detection precision of VHCs lower than 10%. The proposed method exhibited limits of detection for VHCs ranging from 0.1 to 6.2 pptv. Benefiting from the improved trapping efficiency due to water removal, we successfully quantified 34 VHCs at the Shangdianzi background station and achieved a comprehensive assessment of VHCs in ambient air.

Retention behaviour of volatile C1–C3 fluoroalkanes upon selected preconcentration adsorbents

The retention behaviour of several gaseous fluorinated greenhouse gases on carbon-based adsorbents is presented. Retention, calculated on the basis of compound breakthrough volume (BTV), is dependent on the molecular composition of the adsorbate, with compounds possessing chlorine or polarizable hydrogens being better retained than those possessing higher fluorine content. Of the adsorbents tested the carbon molecular sieves (CMSs) of highest surface area show greater retention than those with lower area. Retention of fluorocarbons is generally higher on activated charcoals but this adsorbent type can cause irreversible retention, possible degradation and is more difficult to use practically due to its heterogeneous composition. These breakthrough volume results can be used to determine the best combination and quantities of each adsorbent that can be used within a preconcentration device with a view to developing an analytical system for the determination of fluorocarbon gases in low concentration air samples.