Problem with Argon Carrier Gas in Shimadzu 2010 GC

[salgham2]

Hi
I am using Shimadzu 2010 GC to analyse gas mixture of CO,CO2,CH4,C2H6,C2H4 and H2
my system is configured as follows:

Carboxen 1006 column-TCD-Methanizer-FID ( all connected in series) and using Argon as a carrier gas. My problem is that the base line is stable untill the temperature program of the oven start. Then, huge peak starts to show in the chromoatogram. This probelm started when I started to use Argon as carrier, but I didn't have this problem before when I was using Helium at the same conditions. My oven program is as follows:
40 for 8 mins
then heat up to 210 at rate 22 oC/min and hold for 15 min
So, my problem starts when the temperatures starts to ramp (i.e. from 8 min)

I appreciate any advice on that
thanks

[chromatographer1]

If conditioning doesn't eliminate the peak, then you need to figure out what is coming off the column creating the peak.

You did not state if the TCD sees the peak or the FID. It is an important piece of information.

An impurity in the argon?

Suggestion: Use helium as before. BETTER: use hydrogen as carrier and use second train to TCD but use nitrogen carrier instead. You will need two channels to collect data of course.

good luck,

Rod

[AICMM]

salgham2,

Two comments. First, argon typically has nitrogen in it from the production process. So, isothermally you could have reached breakthrough but as you program the column it starts to come off. For this, you might consider a getter purifier. Two, water is a distinct possibility as a culprit. If you are not drying your gas or you are using any polymeric tubing to feed your system, water will start to cook off when you ramp the oven. No polymeric tubing and a good water trap (the one trap I have installed on my carrier gas lines, which I do to prove a point but that is a story for another day....) would be a good idea.

Best regards,

AICMM

[salgham2]

Thank you all for your commnts.

As for your reply Rod,
The peak ( huge one) shows in both the TCD and FID ( they are connected in series).
I will try to go back to helium and see if it solves the problem, at least I can confirm whether it is related to column conditioning or to the purity of the Argon gas I am using.

As for your reply AICMM,
I don't use any polymeric tubings, and the Argon I am using is with high purity (99.999%).
I assume water is the problem in this case, although I am using the same helium purifier tube to purify Argon as well.

Thank you all agaon for the replies

salgham2

[chromatographer1]

The FID response is troubling.

There may be some problem of the column phase decomposing? or is it trapping hydrocarbons from the new cylinder of Argon?

I would change gases and see if the problem remains or goes away.

best wishes,

Rod

[AICMM]

salgham2,

So I go down in flames on this one.... won't be the last time. Not water, won't respond on FID. Might cause issues, but does not respond. Has to be something else, most likely a hydrocarbon or perhaps some weird flow issue (although not usually an issue with FID.) If you switch back to helium, do yourself a favor and run the argon under the same program and see if you see a peak.... Can you post a chromatogram?

Best regards,

AICMM