Chromatography Forum

We are running an Agilent 7890A coupled to a 5975C MS.

The system is a few years old, and we normally run in split mode.
We have had the need to increase our sensitivity, and tried doing a splitless injection for the first time. When loading the method in Chemstation for splitless mode the inlet pressure bounces up and down, and obviously the GC never reaches ready status. The system is tight and I can detect no leaks. I tried doing a 1:2 split to see if that would show similar symptoms, and it works fine. We normally run in split mode at 1:150. I am baffled. Short of pulling the EPC unit and sending it out for a refurbish, just wondering if any one might have any other ideas as to what might be the cause. Any input would be greatly appreciated.

Every now and then my 7890 does the same thing. Normally just cycling the power will fix it. Not sure why it will lose the ability to control the pressure, but it does.

James,

Thanks for the advice. I do believe that I have recyclyed the 789oA.
I will give it another shot in the morning.
Will let you know what happens.

Hello

Try to create method from scratch (load DEF.M) Try to avoid changing existing method.
I've had this issue few times and it helped...also you can try to remove S/SL EPC from GC configuration, then reboot GC without EPC configured and then reconfigure it again.

Regards

Tomasz Kubowicz