Chromatography Forum

hello!

My instrument is agilent 7890 with flame ionization detector.
With every column and every method I use, i'm getting a drift in the baseline.
It doesn't matter if the diluent is water or any other solvent (DMSO,DMF...).
It doesn't appear in all injections and comes and goes with no apparent reason.
Injection with steady baseline:

Injection with Drift:


Any ideas what is causing this problem?

Someone? Please
(BTW, sorry about the spread chromatograms pics)

Run several consecutive blank runs (no injection) and check if the baseline is O.K.

I did, and the drift appears even in blank runs with no injection.
If i'm running a sequence with 30 vials, the baseline can start without any interference and than start to drift for a few injections and than resume to be normal.

I did, and the drift appears even in blank runs with no injection.
If i'm running a sequence with 30 vials, the baseline can start without any interference and than start to drift for a few injections and than resume to be normal.

In this situation I would check FID itself with column disconnected and FID inlet blanked. Again run several runs and you will narrow your problem either to FID or the rest of GC.

Someone? Please
(BTW, sorry about the spread chromatograms pics)

The reason that I (and I suspect others) have not responded is that I have no information to go on. You tell us only what model of GC you use and that the problem occurs with several diluents, columns and methods. The selection of diluents you list are not typical for liquid injections, so I could guess that you are doing headspace, or maybe purge and trap.

Troubleshooting requires details of methods and systems. None of us are telepathic. The more you don't tell us the more we can't help you.

Peter