Seeing peak towards the end of the run

Hello Guys,

I am using Agilent 7890a GC with an FID detector. Last week I saw that there are few ghost peaks in my chromatogram, so I decided to bakeout the column. After baking the ghost peaks disappeared but now I see and increase in the peak towards the end of the run (please refer to the attached picture). I cleaned the liner, even put a new one and also trimmed the column a little bit. Problem still persists.

Do you have any idea why this is happening and what would be the solution?

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0 dmarchini over 5 years ago

Hi Oishi
It could be the column bleed; I've noticed this getting worst if I bake the column in presence of air.

I usually change the liner, than run a solvent vial, then I bake for 2 hour, until the baseline get flat.

I don't think it is necessary to bake out for longer than 2 hour.

If you don't have peaks of interest on the bleed baseline you're doin good ; If you need good peaks on the bleed baseline I suggest to slow the gradient, I mean, it's seems you have like 50°C/5 min ramp or similar, it's too extreme.

greetings
Dario
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0 dmarchini over 5 years ago

Hi Oishi
It could be the column bleed; I've noticed this getting worst if I bake the column in presence of air.

I usually change the liner, than run a solvent vial, then I bake for 2 hour, until the baseline get flat.

I don't think it is necessary to bake out for longer than 2 hour.

If you don't have peaks of interest on the bleed baseline you're doin good ; If you need good peaks on the bleed baseline I suggest to slow the gradient, I mean, it's seems you have like 50°C/5 min ramp or similar, it's too extreme.

greetings
Dario
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