negative baseline drift

[nabearup]

I'm getting a negative baseline. I have changed the liner, septum, checked the column's connections. How can I fix this?

[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.

[Ron]

It sounds like the detector does not have the zero set properly. Please give more details, type of instrument, detector, etc.

[nabearup]

It's an FID. 6890 GC. There is a temperature ramp.

[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.

[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?

[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.