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GC-MS with Hydrogen Carrier Gas

25 Aug 2012

At the LECO Australia Separation Science Users Group Meeting last Friday in Sydney, my colleague from South Africa, Peter Gorst-Allman, made a presentation on using hydrogen carrier gas for GC-TOFMS and GCxGC-TOFMS.  His preliminary results were quite encouraging, as he noted no obvious deterioration of mass spectra quality for a wide variety of compounds, including such pesticides as the hexachlorocyclohexanes, which can be problematic when hydrogen is used in an electron ionization source.  Somewhat surprisingly, the sensitivity drop was only marginal for most compounds, and he noted a slight increase in sensitivity for a few compounds versus helium carrier gas.  This almost-equivalent sensitivity could be due to the fact that the peaks are narrower (and taller) when using a faster carrier gas like hydrogen, which helps overcome the increased MS pressure that happens when turbomolecular pumps, like those used in LECO’s Pegasus TOFMS, have trouble pumping the ultra-light hydrogen.  However, the pump on the Pegasus 4D GCxGC-TOFMS is a beast, the Varian 551, which pumps hydrogen at over 500L/sec.

a man giving a presentation