Chromatography Forum

Hi

I've been experiencing a very noisy TCD baseline. The GC has been working well for the past 5 months, with a steady baseline most of the time, but noise does appear sporadically. Recently the noise has worsened and persisted to a point were it is interfering with analysis. I have done the usual troubleshooting: checked for leaks at the column injector inlet and detector outlet, conditioned column (190oC) and TCD (375oC), changed septum and changed the wool in the glass liner. I think the noise may be due to a contaminated gas trap/filter or possibly electrical interference.

Please advise me further.

The GC operating conditions are listed below.

Injector temp: 250oC
Column: Carboxen 1000
Column temp: 40oC,
Column carrier: 30 ml/min N2
Detector temp: 275oC, bridge current: 30 mA
Sample injected: 500uL syngas (CO + H2)


Regards
Byron

Hi Byron,

In this case it looks like you have done all you can in solving this problem that you encounter, Is your column Capillary or Packed Column?

If its a Capillary I would advise you to check for a possible breakage in your column, if this inspection comes negative means no breakages

then you can look at in other things like checking if whether your gas is not contaminated or your Detector is not damaged.

I look forward to your reply.

Regards
Ayanda.

Hello

I'd recommend:

- plug detector with blank nut and see if baseline is stable. If it is - you have problem with carrier gas/inlet/column
If it is not - you have problem with detector - gases (purity or leaks) or with detector cell

Regards

Tomasz Kubowicz

Thank you for your responses.

Tomasz, I have capped and isolated the detector as you recommended. It gave a very stable baseline. That should also mean that the carrier gas is pure.
I reattached the column to the detector and conditioned it up to 375oC (max is 400oC), it gave a steady baseline that lasted 1 day. Afterwards I changed a column to one which we know works well. The noise was still observed. Thus far, the detector, carrier gas and column seem be to working. I think that the noise may be due to an electronic fault. Please share your thoughts.

Regards
Byron

Hello

Please paste chromatogram with "problematic" baseline.

Regards

Tomasz Kubowicz

Below are the chromatograms

Thank you for assisting





The first chromatogram has a relatively stable baseline before the baseline deteriorated (normal operation). The first peak is hydrogen (1 min), the second peak is carbon monoxide (6 mins).

The second and third chromatograms show the noisy baseline.

Kind regards
Byron

Hello

What GC have you got?

Regards

Tom

The GC is a Shimadzu 2010 plus.