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negative baseline drift
Posted: Wed Jul 09, 2008 3:01 pm
by nabearup
I'm getting a negative baseline. I have changed the liner, septum, checked the column's connections. How can I fix this?
Posted: Wed Jul 09, 2008 6:45 pm
by skunked_once
Try to maintain a positive attitude! Sorry, I couldn't help myself
Please post more details so that we can have a clue about what the cause could be.
Posted: Wed Jul 09, 2008 7:44 pm
by Ron
It sounds like the detector does not have the zero set properly. Please give more details, type of instrument, detector, etc.
Posted: Wed Jul 09, 2008 7:54 pm
by nabearup
It's an FID. 6890 GC. There is a temperature ramp.
Posted: Wed Jul 09, 2008 9:15 pm
by skunked_once
Still not enought information! Give us as many details as possible about your system and analysis parameters. Have you double-checked everything (gas flows, detector signal, etc.)? It's always a good idea to have a written record of all parameters when the system is working well in order to compare when problems arise.
problem solved
Posted: Thu Jul 10, 2008 3:04 am
by nabearup
I took the column out, and put it back in, and i don't have the negative drift. But now I'm having another problem. My chromatogram looks like there's an indication of column bleed. I ran a column compensation and that didn't help. SHould i try a new column?
Posted: Thu Jul 10, 2008 6:27 pm
by skunked_once
Are you seeing column bleed from the same column that you used before that did not exhibit bleed? If so, one possibility is oxygen getting in from a gas leak. You can certainly try a new column but in my experience, a new column may exhibit more bleed than an aged column. Check your connections and parameters again.