From helium to hydrogen...?

[chemwipe]

Just found out that helium is impossible to get from my gas supplier.

Helium and nitrogen are what I'm currently using for my GC-ECD analysis of PCBs.

Any tips on making the switch from helium to hydrogen? I know there are options I need to change within my old Chemstation software.

Thanks,
John

[chromatographer1]

regulators of gas supplies are different for hydrogen.

detection of leaks can be done differently.

You should have venting of the splitter flow to a hood or outside area.

You will find the chromatography will be faster by 30-50% with almost the same separation.

There must be more things to remember.

best wishes,

Rod

[Bart_chromato]

I do not have experience with hydrogen as a carrier myself, but I do know that older GC systems sometimes have to be converted for them to be safe to work with hydrogen. This is to prevent possible hydrogen build-up in the oven and risk of ignition. So best check if your system is suited before you make the change.

Succes with the switch,
Bart

[gcguy]

We have run several GCs on hydrogen for at least 20 years and have had no issue whatsoever. Cheaper and better in terms of chromatography. Recently we had a go at using hydrogen on mass spec....not much success for the compounds of interest for us, but most of other compounds we looked at were ok.

Switching to hydrogen could give you the opportunity to use narrower bore columns and achieve really fast seperations (most of ours now run in the 60-120 seconds range).

GCguy

[KM-USA]

I'd go with a hydrogen generator instead of cylinders though, much safer. You will need to adjust the flow conditions a little, there are software guides for this.

Some vent their split flow to a fume hood, some use hydrogen warning monitors as well.

Some suppliers seem to think that in a decently-vented lab that venting such into the lab itself never gets even near the minimum hydrogen explosive level.

[chromatographer1]

That is a wonderful assumption. I assume ventilation never gets halted ever because of power outs and mechanical failures. Hydrogen and static electricity are all that are needed in a lab atmosphere to produce really stimulating results...... stimulating.

The Challenger Shuttle was a wonderful assumption.

So was the Hindenburg blimp.

Have I made my point yet?

best wishes,

Rod

[gcguy]

We vent directly into our lab atmosphere. We run our fumecupboards constantly coupled with a managed air intake. Yes I get the point about making assumptions that the extract systems keeps the H2 level below the danger point, however in the event of a power failure most modern GCs would shut off the H2 flow using the flow control valve which is held open against a spring. Moreover, in the event of fumecupboard or lab exhaust failure most labs would require to be evacuated, for us very loud alarms go off and part of our safety procedure is to shut off the H2 lab supply if the labs are evacuated.
Most modern instruments allow the reduction of split flow following an injection and generally this is to a flow than an unlit FID, which would have the same potential to allow the build up of H2 in a lab.

GCguy

[DR]

The Van Deemter curves for H are better than those for He, and it's best to use a column oven with a magnetic catch rather than a mechanical one (think "safe blow out panel").

Although I have never experienced (or been around) any H related lab explosions, appropriate engineering precautions should be taken to bring the risk of an explosion to a nadir.

[chromatographer1]

Back in the middle 1980s I had ventilation installed around the GCs, especially over the FID detectors so that if the FID flame went out the hydrogen continues flowing out of the lab to a roof vent.

Lots of chlorinated solvent was burned in those GC detectors (8-12) whose byproducts were not good to breathe as well.

And we had great lab air exchange. Safety is so cheap compared to the cost of health problems and the danger of fire - explosions.

Be safe out there.

Rod

[burnt1tofu]

Excellent separation, and using a generator gets rid of the hazards of pressurized cylinders. We have many GC-FIDs in lab, all of which have Hydrogen as the carrier gas. The hydrogen source is a generator and we do not vent the split lines into the hood; we have enough air flow in the lab. If you do run hydrogen, I would check your gas lines periodically; even though the lines don't get moved much, we do check, and find leaks in the fittings every once in a while.

[KM-USA]

The hydrogen source is a generator and we do not vent the split lines into the hood; we have enough air flow in the lab.

That's also what the hydrogen gas generator engineer told us we could do: just vent into the room, would never build up to the explosive limit, considering room size and air flow.

But our company "safety experts" will NEVER let us do that. And they'll make us have hydrogen sensors/alarms too. They've seen the films of the 1937 Hindenburg disaster....which overrides the facts....

[chromatographer1]

Remember hydrogen rises, no fan or mechanical device needed.

just punch a hole in the ceiling-roof and the problem literally goes away. (too well sealed a room allows it to congregate in high concentrations near the ceiling - light fixtures.)

I once worked in a building where a whole cylinder of hydrogen would on occasionally leak at once (a few minutes time) when a regulator would fail. Scary? no, because there was a heat exchanger built into the attic which vented the hydrogen outside and away, operated by the rising warm air or hydrogen gas leaving the building.

It is nicer to have a tube or some other physical passage to use to vent. And a simple 'u' ending with screen keeps the bugs/mice/bats out. Most buildings already have a hot water heater vent or furnace vent or even a hood vent.

Safety is never expensive, but saving money can be. Mistakes can be costly, but are stupid when foreseen and ignored.

best wishes,

Rod

[burnt1tofu]

But our company "safety experts" will NEVER let us do that. And they'll make us have hydrogen sensors/alarms too. They've seen the films of the 1937 Hindenburg disaster....which overrides the facts....

I love that you mention the Hindenburg...I've wanted to put some of our GCMS on hydrogen as a carrier gas, see if I could make it work, but old school chemists say it could go boom in the source...like the hindenburg. An uphill battle.

Going back to Hydrogen on GC's, if you are going to use hydrogen generators do some research, not all gas generators are equal.

[jdezeeuw]

There is nothing wrong using hydrogen as long as you know how to work with it. We tested millions of columns the past years , only using hydrogen.

If you want increase safety? Use flow control setting. as soon as column snaps at inlet, your GC will jump in stand by or off mode as it cannot built up pressure.
Need more? invest in H2 sniffers ( kind of leak detector that check oven-air);
More safety? Use MXT metal columns, they are compatible for 95% of all applications.

For those afraid of ventilation of hydrogen in the lab, please make some calculations what you have to do to get >4% hydrogen and keep in account how fast hydrogen dilutes.

More interesting is H2 in MS: I hear different stories:
some general info: You loose about 3x sensitivity, you need to deal with the higher flow (or use 0.18mm), you have to verify spectral integrity as masses may be impacted (maybe need to make own library). Of course make sure you have no air/H2 in the MS. It will not kill you, but you have to be ready to wait for a service engineer (and a big $$ cost).

For those that suffer from The Hindeburg syndrom, I would say: If you know what you are working with, there is no problem, but you always have to use the brains. Would we also "ban" gasoline if some people decide to light their cigarettes while fueling their cars?

jaap, Restek Corporation