Chromatography Forum

Hi everyone!

I have an interesting problem with my GC-FID. We are doing our analysis and we are randomly getting spikes on our chromatograms. It's not all the time but after about 100+ injections, we get one chromatogram with a spike like the one posted.

I was concerned that this might be telling of a larger problem or impending failure of some sort. I've cleaned the FID and replaced all my supply gases.

Any information and / or help would be much appreciated.

https://ibb.co/2c7wjMQ
https://ibb.co/Dbvc3KK

Sounds like FID may need cleaning; or, could be breakthrough of late eluting peaks.

We had a similar problem; so, I made a bake-out instrument method that is programmed to start at the lower test method temperature, then ramp quickly up to the upper column temperature limit, then hold for at least 60 minutes. Since the method starts at the lower temperature, the oven automatically reverts to the initial temperature after method completion.

This method is on the last injection of every analytical run (automated Sequence) so that it is always performed. Thus, the lab techs do not have to remember to perform it.

I found that I do not have to ramp up the Inlet and FID temperatures, since the oven ramp has solved our intermittent spike problem.

Hi
Are you clean up a jet hole?

Sometimes I watch the very short and high intensity peak. It's all because of soot on the jet

Thank you for the replies!

I'll look in to cleaning the jet / replacing it. I'll reply with my findings after doing so.

In fact one time in 6 month into jet collect's restriction from fired compounds. It blocking the gas move! I remove blockage by thin cord and rinse by some organic solvent

Try taking out the jet and making sure you can see through it and don't have a build up within.

you could also try having your inlet and detector set to a higher temperature for a little bit before running your analysis.