Have you switched to hydrogen carrier gas? What are your experiences?

Using hydrogen as a carrier gas has been tested on our new Refinery Gas Analyzers and even shows an improvement in sensitivity on the TCD due to the difference of it's thermal conductivity compared to other analytes. See the link to presentation starting with slide 22 Alternative Carrier Gasses for more info.  This presentation was given by Roger Firor and JAMES MCCURRY for C&EN

Here are some tips in no particular order:

You must be careful with halogenated solvents and carbon disulfide as you may make acid in the inlet when using hydrogen carrier.  Some analyses cannot be run with hydrogen because of that.

The optimum carrier gas linear velocity is different than helium so use the available tools to get it right.

The signal to noise ratio on a GCMS system will be less than when running helium - up to 2x to 5x worse.

Library matching will not be the same as when running helium.

Hydrogen scrubs the inside of the gas regulator and supply tubing and you will see more noise for a while -- up to a few weeks -- as it does a better job cleaning than the manufacturer.

Make sure and read the Hydrogen Safety Manual -  G3870-90101.

The MSD pumping capacity for H2 is approximately 1/2 that of Helium.

– Performance turbo: 2 mL/min

– Standard turbo: 1 mL/min

– Diffusion pump: 0.75 mL/min

– Pressure pulsing: turbo < 3 mL/min, diffusion < 2.5 mL/min

Attached are the documents on switching from Helium to Hydrogen for GCMS.

We have about 20 GC's and GC's with HSA units.  That's 34 FID's total.  We made the switch to hydrogen years ago (like in 2000) when He availability first became an issue.  We run all of our FID's with H2 and use N2 as the makeup.  We have a few TCD's that we still run with He as we found H2 or N2 to not work well for us in those applications.  We have one H2 generator that we supplement with cylinders...it is currently in for repair.  Since the cost of He has just kept climbing (over $300 now) we have saved literally thousands of dollars on gases over the years.  We have had zero safety issues.  Most modern day GC's have safety shutdown built in.  And paying careful attention to gas usage will flag leaks if they occur. 

We are an industrial QC lab, so have some flexibility in the methods that we run so we can choose whatever flows and such that get us the resolution and reproducibility that we need.  If you are locked into regulated methods you may not have that flexibility although I have noticed some ASTM methods finally having some flexibility to use H2 instead of the default He. 

There are calculators available on-line from several companies to help make the switch in terms of flows and such.  I think Agilent has one.  I know Restek does.  If you are using OpenLab or ChemStation software it is pretty easy to set methods up using an optimum linear velocity (which is significantly different for H2 as opposed to He).  As long as you have specified H2 as the carrier it will do all the calculations for you. 

Hi Crystalnipp (great username!!)

Thanks for the clear answer I do have a question for you.

We also run N2 make-up to our FID.

As of now we run He and our night standby method is to leave the GC oven at 150°C with 0.5mL/mim He flow. We turn flame and gasses off on FID, leaving only make-up gas.

In the morning, the GC is ready to operate in under 10 minutes for ASTM D5501 method.

Now, when switching to H2, if I send 0.5mL/min of H2 in our standby method, should I leave the flame ON at night then ?

Thanks in advance !

I would leave the flow on and flame off for standby.  The H2 is really just dissipating into the atmosphere and isn’t at a high enough concentration to cause issues.  We leave ours like this all the time.  And we have some 40 inlets plumbed with H2 going at the same time in one room.

Crystal

{Personal Details Removed by moderator}