Switching from helium to nitrogen as a carrier on HS/GC-MS(5977MSD/8890 GC/PAL RSI 85)

Hi all what is your experience using nitrogen as a carrier vs helium? Pros and cons...We have a 5977MSD with 8890GC and PAL RSI 85.  We are testing residual solvents currently pentane and ethanol on in process samples.  Is there literature available ?  I cannot seem to find any in here using keywords.  Thank you in advance for your input.

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  • It is neither turbo nor rough pump related. The available helium conservation module that mounts into the GC switches to nitrogen and the system tolerates pumping that just fine. Nitrogen is tough in any GCMS ion source due to chemistry and physics. It is a much larger molecule than either helium or hydrogen and gets in the way. It also ionizes and can cause unwanted space charge effects and odd spectral tilt.   

    In the GC column, the optimum linear velocity is about 1/2 of that for helium and ~1/4 that for hydrogen.  It is necessary to run at lower flow rates for decent chromatography. https://www.chem.agilent.com/cag/CABU/carriergas.htm .   

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