Chromatography Forum

If I am buying Ultra High Purity gases (He, H2, air) for use with my GC-FID, is it still necessary to put O2, H2O, etc. traps in the lines? Which gas lines is it most important to have the traps on? And what traps would be recommended at a minimum?

Thanks.

It is the columns which benefit from the traps and the high purity gas you purchase to protect them.

I would suggest you review page 421 in the latest Supelco catalog or talk to their customer service

880-359-3041 voice fax 800-359-3044
or email: techservice@sial.com

Remember that the air you supply to your FID should be hydrocarbon free or you will have a high background signal and noise in your signal.

Hello QZ,

if You are using extra pure gases it's not so important to use these traps, if Your gas tubing is short AND the connectors are tight AND the GC has no leak inside (including a small one) AND Your column is apolar or middlepolar it's ok to work without,
in all other cases please use a oxygen and moisture filter in the following order:

first moisture and then oxygenfilter for carriergas.

Regards
Bernd

Years ago someone convinced us to use a trap assembly (if I remember it was from Chrompack, now Varian?) on our 99.96% (or so) N2. We got unstable baselines from the FID after that, the problem was gone again as soon as they were removed. (KISS principle)

In the past, I didn't use traps on my carriers or hydrogen, because we were paying premium price for high purity. The air was house air and I purchased a Whatman Zero Air generator. I never saw problems with gases in 10 yrs.
Recently, we moved the lab and the gas system came with a set of traps. The traps were in service about 3 yrs when they clogged. I arrived at the lab with 30% of the GC's alarming or shutdown. Low pressure inlet alarms. A little detective work back to the hydrocarbon trap. Luckily, the people that installed the traps also installed by-passes. I was able to by-pass the clogged trap and continue to analyze. I didn't notice any exceptional FID noise from the by-pass and ran that way for about a month while waiting on replacements.
I'm not sold on the traps, but I put alot of faith in the purity of the gases supplier.

HI
Keep your many for better aims.We are using control instrument Air, 99.999% Hydrogen in cylinders, 99.99999% Helium, and N2 from air separation industrial plant, with no traps at all. and for more than 20 years we didn't have problems.

Hi
I use air house for GC, (by using the pump);is it a source of noise in the base line?or is it a problem?
thanks
sorry for my english.

Hi
I'm sorry for you!
Using room air with pump is very very bad!
you have to use a compressor and a large tank to keep the pressure constant, you must use a lot of filters and dryers:
1) filter to remove oil and particles from the air
2) demister to remove drops of water and then a dryer to remove water ( filled with Silica Gel or Molecular Sieve)
3) filters/absorbers to remove organic traces from the air.
in some applications you must to remove CO & CO2 from the air.

I hope this will help you, and you can contact me by e-mail: arie.katzir@caol.co.il