Hydrogen measurement

[srikanthearpina]

How to measure Hydrogen gas using GC and what is the suitable detector?

[Peter Apps]

I measure the hydrogen on my GC with a bubble flow meter, cheaper than an electonic flow meter, doesn't need calibrating, and needs no batteries.

Peter

[chromatographer]

Hydrogen content in gas is easy to separate from other gases and measure with GC. Some suitable columns are mole sieve, hayesep, poraPLOT/porapak. A TCD detector with argon carrier gas works well and gives good sensitivity. For even better sensitivity a PDID detector works very well.

[chromatographer1]

Hydrogen is not so easy to separate from helium or neon on porous polymer columns.

Mole Sieve or Carbon Sieve is a better choice for packed or capillary columns.

Also, many prefer nitrogen carrier using a TCD. Using a pDID one will not detect helium if that is a concern as helium is the carrier for that detector.

best wishes,

Rod

[srikanthearpina]

I measure the hydrogen on my GC with a bubble flow meter, cheaper than an electonic flow meter, doesn't need calibrating, and needs no batteries.

Peter

Hi Mr. Peter,

Sorry for the wrong way of posing my question. I want the method. not about the flow meter. but can u tell me how to determine the flow rate at which the sample hydrogen gas has to b injected?

[chromatographer1]

the hydrogen gas is not injected when flowing, so there is no flow rate.

One uses a syringe or a valve with a sample loop.

See Valco web site for any details about which you may wish to inquire. WWW.VICI.COM

best wishes,

Rod

[chromatographer]

This is an example of hydrogen on a TCD with argon carrier and a porous polymer packed column - hayesep D. The helium and hydrogen are well separated. The nitrogen response is positive because its thermal conductivity is higher than argon's.

[GasMan]

Chromatographer,

Can you please post more information on your column and conditions. All of the literature that I have looked at for HayeSep D does not show this sort of separation for these gases.

Gasman

[chromatographer1]

The chromatogram from Chromatographer is probably 9 meters in length and 1mm ID.

His temperature is probably sub-ambient or barely ambient.

And the sample size is most likely quite small.

That is just a guess.

But such separations though possible do take longer than a short MS5A or MS13x.

A 10ft MS5a column will separate He and H2 in less than 60 sec at 40°C for example.

A 20ft Carboxen 1000 at 40°C and 30 cc/min nitrogen



Rod

[chromatographer]

My chromatogram was done with two 6 meter x 1mm 80/100 HayeSep D's allowing a back-flush of heavy's. The oven temp was 35C and column head pressure 95psi. The injection volume was 25ul.

I don't want to get into a pissing contest here but I will just say that the Hayesep has worked very well for me for many applications. But, the extra minute or two of analysis time does require enormous patience .

[chromatographer1]

Dear Chromatographer,

No spitting or pissing here. I am always happy when any analysis works, no matter how it is done. Your application is an attractive one, especially if one already has the columns available.

I see I wasn't too far off in my guess. 40 ft of column (12 meters) and 1mm ID. I guessed 30 ft. and 1mm.

Yes, I have done this separation in low concentrations with a 9m of Hayesep N but at 80°C but the dead space of the system is critical at those specifications.

The real issue I suspect for the casual analyst is the cost of the columns. A 10ft MS5A is probably less than $120. What does a 40ft (12m) Hapesep D cost?

The other issue is limit of detection.

MS5A has a fairly low capacity for sample, much like the 1mm HS D.

With the Carboxen 1000 the capacity is much higher, allowing detection of a very trace amount of Helium in Hydrogen and vice versa.

But whatever works is the KEY.

best wishes to all,

Rod

[Peter Apps]

I would expect the head pressure to be too high for the average GC's pneumatics also - are these long packed columns used in dedicated intruments ?

Peter

[AICMM]

This is so easy with an HID (PDD or DBD.) Of course I am biased since I make the DBD but it seems that this is a common question and this application is super simple with the helium ionization detector. Plus you don't have to worry about argon for H2 and helium for everything else, negative peaks, poor sensitivity for some and good for others.....

Below is a chromatogram of 0.9 ppm H2 standard in nitrogen run using a slightly long mol-sieve column on a 5890 GC using the standard FID electrometer card and the make-up flow controller from the HP FID flow control block. The application uses a 6 port valve and the standard packed port flow controller. The only thing remotely different about this GC was that I used a purged valve head.

Best regards,

AICMM

http://i54.tinypic.com/2wnnypk.jpg

[chromatographer]

Hi AICMM,

Can you give me some more information on your detectors? Is DBD the same as PDD? Do your detectors have an advantage over some of the other similar detectors on the market?

I saw a previous post that gave the web site detectorsbyaic.com do you have a new site now?

Thanks!

[AICMM]

chromatographer,

I am in the process of launching a new site but not there yet. (Unfortunately, I don't know how to correct my post info (yet) so I will have to do that when I re-launch.)

As usual, there are similarities and differences between the PDD, the DBD and the older Gow Mac HID. Not wanting to make any kind of sales pitch, I would be happy to send you more info about the DBD and how it is similar or different from others if you want to contact me directly at aicmm at flash.net.

Best regards,

AICMM