GCFID NOISY BASELINE

[seamoro]

Our GCFID has got very noisy baseline all of a sudden. Do i need to clean the detector and how do i do that?

[seamoro]

the baseline noise is cyclic. There is a peak followed by by a negative and this continues every couple of minutes

[seamoro]

We recently changed our method to a pulse split method:
Injection Pulse Pressure 30psi until 0.5min
split ratio 10:1 30ml/min
The method itself is 2 min hold time at 40 degrees. Then ramp up to 170 degrees in 3.25 minutes. then ramp up to 300 from 170 in 4.5 minutes. Then hold at 310 degrees for 15 minutes.
The GCFID appears to stop intermittently after 100 injections then sometimes after 40 injections. Is the new method causing this? We are using N2 as make up gas. H2 and air as carrier gas

[gcguy]

I have a special heavy handled screwdriver that sometimes works on noisy FID baselines. They can be prone to dust building up and a couple couple of thumps with the special tool can fix the problem.

GCguy

[Bigbear]

If it is cyclic in nature I would check that all the electrical connections are tight.
I had a similar problem once and it was due to a freezer sharing the curcuit. Baseline disturbances when the freezer compressor cycled!