Chromatography Forum

I’ve had the Agilent7000C for over 2 years now and have been running He as carrier. I have a few questions about hydrogen carrier. I have used H2 with GC-ECD (Thermo) but never with GCMS so if there are 7000C operators that have been using hydrogen, please chime in. Specifically:
1. Do I need to have some kind of H2 sensor installed in the GC to prevent unsafe conditions (in case of a leak)? Or do I just switch to H2 in the GC configuration?
2. How long does it take to condition the instrument for H2 use?
3. EI / EIEX autotune and DFTPP tuning - any issues?
4. Is it OK to use in CI with CH4 and/or NH3?
I will be using dedicated SS tubing to feed from the H2 tank. It is brand new and fairly short (less than 5 feet). I realize I still have to have He line for quench gas.
Any experience and suggestions you can give me will be appreciated!
Thanks.

I think you don't need quench gas if you use H2 as carrier, just nitrogen for collision.
Also don't expect to use higher flow than He, turbo pump is not ideal for H2 carrier, you should be ok with the same flow as with He (1-1.2 ml/min.

Regarding safety, just make sure to remove the front window cover and remember to shut the carrier supply off when the pump is not working.

I think James is running his 7000 with H2, just wait for his answer to have more informations!

I have mine setup so I can switch between He and H2 carrier and have used both.

With H2 you no longer need the He Quench gas if you are doing MRM. If doing single quad work turn both Quench and Collision gas off. Tuning may need a little tweaking but it is fairly close to the Helium tune for DFTPP and I have not had much trouble getting it to pass. BFB tuning is a whole different beast though if you try to run volatiles with H2.

You will see what looks like hydrocarbon contamination for a week or two after you make the switch for the first time. This is normal as the H2 is cleaning out all of the lines on the instrument. Elevate the temperature of the source and scan it a little each day the first few days and you will see it getting cleaner as time passes. I would give it a couple days before trying to do serious work though.

I have mine setup so I can switch between He and H2 carrier and have used both.

With H2 you no longer need the He Quench gas if you are doing MRM. If doing single quad work turn both Quench and Collision gas off. Tuning may need a little tweaking but it is fairly close to the Helium tune for DFTPP and I have not had much trouble getting it to pass. BFB tuning is a whole different beast though if you try to run volatiles with H2.

You will see what looks like hydrocarbon contamination for a week or two after you make the switch for the first time. This is normal as the H2 is cleaning out all of the lines on the instrument. Elevate the temperature of the source and scan it a little each day the first few days and you will see it getting cleaner as time passes. I would give it a couple days before trying to do serious work though.

Thanks for the tips! I may have to stick with He for now since I don’t have 2 weeks to spare…...

You could try it overnight and see if the background comes down enough. The two weeks will give you the best baseline though, but the last little bit comes down really slowly.