Ar instead of He?

[dominika1]

Dear All,
Can Argon be a replacement for a Helium? If not, why? Did anybody try?
I use GC FIDd/FPD for geo-organic matters like derivatized lipid extracts, fatty acids etc
Most of the time if they are any talks about carrier gas then only N, H, He and what about Ar?
I don't want to use a hydrogen. Nitrogen is not good enough and will not give us a good results.
cheers

[Peter Apps]

The disadvantages of nitrogen compared to hydrogen and helium are even worse with argon because it has an even higher molecular weight and viscosity. Why do you not want to use hydrogen ?

Peter

[chromatographer1]

If you are using packed columns then I would give Argon a try. But if you are using capillary columns Peter is right as always, it will be a very poorly performing GC. But maybe it might be good enough for your needs? One can only try it and see. Please tell us on the Forum your results.

Prices would indicate that hydrogen would be cheaper, no?

A piece of tubing from your splitter vent to a window or rooftop can't be that expensive.

Don't be afraid. Just be thoughtful before putting things into motion, and all will be fine.

Hundred of labs do it every day.

best wishes,

Rod

[dominika1]

Thanks Peter and Rod for your respond. I do know Ar is not the best due to it high viscosity, low diffusivity, etc.
Why not hydrogen? Unfortunately there is too much students working on GC's (at university), and who knows, which one is a hidden pyromaniac who would love to experiment with hydrogen. too big risk.
We have on-column injection in capillary GC's.
We do have also GC/IRMS and over there hydrogen is absolutely not an option.
I think I will give a try with Ar, would cost me nothing, and i am interested on how would that work on my type of samples. Although it will definitely take too long to get the results finally, if any.
If i'll do it i will definitely share my experience with it.

best wishes, Dominika

[chromatographer1]

Thank you very much.

I would recommend that you use slower flow rates (as with nitrogen) for best chromatography, although, of course you might use temperature programming to speed up the analysis.

best wishes,

Rod

[RhysB]

Why not hydrogen? Unfortunately there is too much students working on GC's (at university), and who knows, which one is a hidden pyromaniac who would love to experiment with hydrogen. too big risk.

In one of my previous incarnations as a tech at University, we swapped from helium to hydrogen for cost reasons (and the room plumbing was much simpler).
In 10 years I never had a problem with students and hydrogen. Helium was another matter entirely.

[antonk]

Max 200 ml/min split low and 5 ml/min column flow (40 ml/min FID hydrogen burns out).
Ok, FID is not lit.

Max total 245 ml/min of hydrogen. 1 (one) glass of hydrogen per minute at normal pressure.

In what timespan the hydrogen reach required amount in a lab (i hardly imagine lab without ventilation) of volume for instance
10x5x3 m = 150 m^3

[aldehyde]

if you're using Agilent GCs any leak in the inlet will cause a hydrogen shut down with annoying beeping warning within 3 minutes, so as long as no one just opens the regulator and lets it out full blast it really isn't that dangerous.

I'm sure other manufacturers have similar built in alarms when configured for hydrogen.

[chromatographer1]

If a leak is such a concern for you, use the cylinders OUTSIDE of the building and install lines into your lab.

Vent lines can be fed to a window or outside wall for venting outside the building.

Your room should have a hood or the building have other means of ventilation (a vent to the roof is often part of the plumbing or heating system) which would allow hydrogen to escape if released in the lab.

And let me assure you that the tiniest crack high in the room will allow the hydrogen to escape and it really seeks to leave the building in any possible way.

best wishes,

Rod

[RhysB]

When We swapped from helium to hydrogen at the university, the departmental safty officer was worried about possible massing of hydrogen in the oven, leading to the oven door being relocated into an opposing wall.
(Wosrt case scenario. Oven still running but fan dies and there is a leak)
I got round this by drilling a 1/4" hole in the top of the oven and placing a piece of copper pipe as a vent. We also vented the split vent out a window using a long piece of rubber tube
I agree that any instrument room should have enough air movement to deal with any small volumn of hydrogen that leaks.