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- Posts: 3
- Joined: Tue Jan 20, 2015 4:18 pm
I've been having trouble with our HP 6850 GC with FID. A few weeks ago, the FID didn't light as usual when my students tried to use the instrument. I increased the proportion of H2 a little in the detector gas controls and that worked for a few days. When the problem happened again, I tried turning up the H2 even more, but that didn't work.
We use ChemStation to turn the FID "on" (although I've tried the handheld remote control too). After the system brings the gases up to their set points, I do hear the pop noise that indicates an attempt to light the FID, but it doesn't seem to light. The gas flow and the FID signal fall back to zero. The system automatically tries again several times, but I don't hear any pops on subsequent attempts. The online plot shows kind of an "h" shaped signal for each lighting attempt, with a small flat shoulder after the initial large peak.
I've changed and reinstalled the column, hoping that it would help, but it did not. We normally use an H2 generator, but I've connected a compressed H2 cylinder and I get the same problem.
I am thinking of following Agilent's FID cleaning procedure next (or maybe rebuilding the FID), but since that requires significant time and cost, I wanted to ask you all first for advice.