Chromatography Forum

We now have Agilent 7890 GCs running under Chemstation B.04.01 (SP1).

How can we reduse noise baseline in the parameters?

We are experiencing noise like the picture above:

You can improve the noise level by reducing the data rate that you collect the data from your detector. This is done in the "Signals" tab of the "Edit Instrument Parameters" menu (Instrument will be the GC that you are working with).

However, you should not be using the ChemStation to solve an instrument problem, such as a dirty detector or leak in your system, which may be causing your noise.

Gasman

However, you should not be using the ChemStation to solve an instrument problem, such as a dirty detector or leak in your system, which may be causing your noise.

Gasman

Absolutely. Many things can cause stuff like this: leaky septum, plugged syringe needle, detector gasses, too little analyte, leak at inlet.

Yesterday a co-worker was obtaining similar low response, then none, for ethanol assay in hand sanitizers. It was easy to discover that the syringe needle had bent, so the only sample reaching the column was the tiny amount still in the syringe needle. So check the basics, don't assume anything.

bi0hazard,

At what level? If you are talking very low ng's on an FID then sampling rate may help or you may simply be near the S/N threshold. If you are talking 10's or hundreds of ng's then, as suggested, you may have a bigger instrument issue.

Best regards.

HI,
maybe leak in your system or it depending on sample matrix.

There is no absolutly no leaks, GC's are brand new from the box, installed by the Agilent technician.

I'm talking about the threshold I think, or another parameter... when I zoom the baseline, there is noise like this and I would like to reduce it a bit.

I'll post a chromatograph in a bit.

EDIT: GC purpose are FAME. So the matrix is simply hexane. Sampling rate is what I was searching. Ill try to lower that setting to see if there are diffrences.

It may have been installed by Agilent but have you done anything since then? ie replacing any consumables, changing columns? Honestly I still wouldn't be so quick to assume its impossible--while rare we still make mistakes sometimes .

What sampling rate are you using? I think sometimes it gets set at 50 or 100 Hz but for most purposes you want 20 Hz.

I just edited the method and we were using 50hz.

Let's try 20hz.

The Agilent guy tried his solvent mix and it was all good.