Agilent 7890A GC-FID persistent baseline issues
Hello everyone, for the last 2-3 weeks I’ve been battling this GC we inherited from another group that wasn’t very well taken care of. The initial issues were fairly simple fixes with replacing the FID jet, septa’s, split liner, needle, gas lines, etc. (really everything not electronic). It was working finally and I managed to get in a few runs that week before I left for the weekend, when I came back however, the GC refused to ignite in the first week of trying to fix it again. Myself and another colleague figured it was just a flow issue and swapped out gas lines again, that was only part of the problem though because since then every time I’ve run an Acetonitrile blank my baseline has been at ~32 pA where before it was solid at 4-5, you can also see in the chromatograms that after the ACN where there shouldn’t be anything my baseline continues to rise up to ~350 pA. I’ve confirmed by HPLC and another departments GC it’s just as pure as Fisher says. If anyone has encountered an issue like this or has any ideas I’m willing to try anything at this point. Please and thanks!