A dual-channel gas chromatography method for the quantitation of low and high concentrations of NF3 and CF4 to study membrane separation of the two compounds

• Published in: Journal of Chromatography A 2013-09, Vol.1307, p.180-190
• Main Authors: Branken, D.J., le Roux, J.P., Krieg, H.M., Lachmann, G.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; CF4 quantitation; Channels; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography; Copolymers; Detectors; Exact sciences and technology; Gas chromatographic methods; Gas chromatography; Membranes; NF3 quantitation; Pulsed discharge helium ionization; Separation; Separation of NF3 and CF4; Super Q; Switching
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2013.07.101

•A dual-channel GC method is described for quantitative analysis of NF3 and CF4.•The method uses two channels with a TCD on one channel and a PDHID on another.•Divinylbenzene–styrene co-polymer stationary phases provided adequate resolution.•No valve-based column switching or fluorocarbon liquid phase was required.•This method is valuable to studying membrane separation of NF3 and CF4. A dual-channel gas chromatographic method is described in this paper that can be conveniently used for quantitation of NF3/CF4 mixtures with a thermal conductivity detector (TCD) on one channel for the quantitation of high-concentrations, and a pulsed discharge helium ionization detector (PDHID) on a second channel for the quantitation of low concentrations. It is shown that adequate separation is achieved on both channels with this dual single-column setup in which column switching as used for NF3/CF4 analysis in industrial chromatographic methods are not required, thus yielding an effective analysis method for laboratory-scale investigations. In addition, the use of packed columns with purified divinylbenzene–styrene co-polymers as the sole stationary phase yields satisfactory resolution between NF3 and CF4 at isothermal conditions of 30°C, with elution times of less than 8min on the TCD channel and less than 4min on the PDHID channel. Consequently, this method allows for reliable, straight-forward quantitation of NF3/CF4 mixtures, which is necessary when studying the commercially important problem of NF3 and CF4 separation by different methods. Therefore, the applicability of the method to studying membrane separation of NF3 and CF4 is briefly discussed and illustrated, for which the dual-channel setup is especially beneficial.