Chromatography Forum

Everyone,
I have one 7890A GC, working, but in last week I found a problem :
first we don't have conection with software and machine because when I injected sample the time delay a few minutes to start.
second when the run is processing the output decrease at negative pA(11.1pA to -2.1pA) it seem like the detector is switch off, but if you abort it came to the intial baseline.Can help me please?

Just a few thoughts:

-Did you try to reboot the system (switch on and off both computer + GC) to re-establish the connection between the instrument and PC?

-Regarding the FID: It can be that your detector is dirty! Is the flame on (do you see condensation when placing a glass object above it) when in stand-by or when analyzing? Is the signal constant (no considerable fluctuations) when the instrument is in stand-by? I woud check if there is flow passing in the column (put detector end part in methanol and you should see bubbles) and then clean the detector.

Regards,
At_om