we have a HP 5890 Series II gaschromatograph.
We changed lately the capillary column und run now with a varian column for fatty acids.
Carrier gas: Helium FID supporting gases: Hydrogen and synth. Air
Now we have a constantly periodic up and down of the baseline. Looks like a saw tooth pattern.
I tried a run with a standart component and also a blank run (without any injection), always pretty the same.
Have you any idea what kind of problem this could be ?
How would you solve it ?
Thanks for any help !!!
periodic baseline up and down