FID signal - noise at the apex of the peak

[thohry]

Hi all,

I just met this situation: the peaks are more noisy at the top, the baseline seems OK (see picture bellow).
That are hydrocarbon peaks (FID) in a Toga analysis. The GC is new.
Thanks for any inputs.

[Consumer Products Guy]

Almost looks like the time about 30 years ago that I forgot to turn the air flow on to the FID detector. Check the basics.

[thohry]

Almost looks like the time about 30 years ago that I forgot to turn the air flow on to the FID detector. Check the basics.

Thanks for your answer. The GC is an Agilent 7890 and brand new. Anyway, I will check the flow rates of H2, Air and see.

[AICMM]

thohry,

How much are you shooting? Is this a standard or is this a standard in oil or is this just the oil? You are a little noisy for an FID but not that noisy, I am guessing that you are running +/- about 0.3 pA? This is high for an FID but not outrageous. If you think this is too high, I would look at your gas supplies for contamination and then I would look for leaks.

Best regards,

AICMM

[thohry]

thohry,

How much are you shooting? Is this a standard or is this a standard in oil or is this just the oil? You are a little noisy for an FID but not that noisy, I am guessing that you are running +/- about 0.3 pA? This is high for an FID but not outrageous. If you think this is too high, I would look at your gas supplies for contamination and then I would look for leaks.

Best regards,

AICMM

Thanks AICMM for the input.
I injected standards, not oil and it's about 100 ppm (at max). The noise at the peak apex is about 1.5pA for the later peaks. I have put filters in the carrier gas line and it is better, just a bit.

Regards

[Peter Apps]

If the GC is new it should have some kind of guarantee on it, in which case this is Agilent's problem. Did it pass it's installation tests ?

Peter

[thohry]

If the GC is new it should have some kind of guarantee on it, in which case this is Agilent's problem. Did it pass it's installation tests ?

Peter

The installation test is OK, it's C14, 15 and C16 peaks and they all are OK.
This one has FID, Ni converter and TCD. I am thinking about the argon cylinder but not so sure.
Thanks and regards

[thohry]

Thanks all for replying.
It's now OK after conditioning the column, inlet etc.. and gas filtering.