Chromatography Forum

I have very high FID output (8947849) both when the FID is on and off. The GC is 7890A.

Lately we've been running IPA/BTA diluted 100:1 with water (99% water:1% IPA/BTA).

According to Agilent and the EPA 8015(?) method, I can run water samples on GC/FID, although I've always been told to avoid water on GC where I've worked before.

How do I troubleshoot to see if it's electronic or contamination? Is there a schematic of the FID anywhere so I can see the parts broken down?

I found some troubleshooting info that reads I should:

1.) check the internconnect or spring,
2.) contaminated Teflon insulators, and
3.) electronic components

I also want to check the electrometer?

I'm new to FID, and I'm more experiecned with MSD.

Thanks!!!

Sounds like an error code for a shorted-out Agilent FID. I don't have a GC that new (as 7890A), but the older ones did that.

I had a problem on the FID on a 5890 when the detector temperature was too low and water condensed inside the detector and shorted it out. You could take apart your detector and clean it, checking for the presence of water. Put it back together carefully so that the spring doesn't short out and check for correct temperature (> 200 C).

skunked_once,

Since you are doing water injections, I would advise either raising your FID temperature a bunch (depends on the limit of your installed column) or adding a heater to the FID chimney. If you look at the construct of the FID, you will note heater is way far from chimney (through little throat) and, therefore, low heat transfer to chimney.

Best regards,

AICMM

Since you are doing water injections,

I should have explained in more detail. The water that caused the detector to short out came from condensation from the hydrogen flame as a result of the detector heater being inadvertantly turned off I was doing routine FAME analysis at the time with hexane as the solvent.

I bet that it's a shorted detector. Can be the spring is not properly placed or thet crud or water is shorting it.