Chromatography Forum

At the beginning of the day the FID kept losing flow and the detector would shut down. We restarted the GC (Agilent 7890A) and it would run for a little while, then loop around to the same issue. I also checked everything for leaks and found none.

A couple hours ago it changed to a combination of that issue and the ALS (Agilent 7650A) failing. It comes up saying:

ALS Failure State: Ready to Inject
ALS Failure Code 153: Autosampler serial port error.

We removed the injection communication cable and plugged it back in; tried restarting everything (computer, GC, gas cylinders - closing reopening for the flow issue) but haven’t gotten any progress from it. It still drops the flow rates to the detector to 0 or a negative number and refuses to reach a Ready state. I checked for leaks and didn’t find any, replaced the glass liner and septum and we cleaned out the detector as well.
We have no more ideas as to what is going on with this instrument, any thoughts to help us pinpoint and resolve this problem?

Hello

Check Lit Offset value for FID - perhaps it is default (2.0) so try to change it to 1.0

Regards

Tomasz Kubowicz

Was set at 0.0 PA so I changed it to 1.0.

We left the GC off last night and when we turned bit back on it was working without the ALS error. Unfortunately after a couple of hours trying to run suitability the detector flow issue has reemerged. My utility flow says -5.760 ml/min and fuel flow -0.254mL/min. It should be 40 and 400. The make up was set at constant flow and was reading 0, so I tried to turn it on at 2.0mL/min. It does read a flow on that one.

Update: We are thinking it's an environmental issue. There is a high humidity in the lab and its very hot. Since it ran in the morning and quits after it started heating up, and the Karl Fischer is starting to have problems with the humidity now too it seems probable.