I have a method set up on a HP5890 GC equipped with an ECD detector. The problem is the background noise is unstable. In the morning before the instrument is used the noise is low, about 20 mV, but as it's used throughout the day
the signal increases to 50mV and stays there (+-2mV). The background noise is monitored at initial temperature when the GC is at equilibrium.
I don't think the detector is getting dirty from injections because the signal will increase after a run without an injection. Can anyone help?
By Anonymous on Thursday, September 7, 2000 - 11:08 am:
You neglected to say what type of samples you are analyzing. There are a couple of possibilities; column bleed as you program through the run and it then accumulates somewhat in the detector, perhaps some high boilers that are slowly eluting from the column, they are being built up during the runs and then reach a steady state coming off of the column.
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