noisy baseline on 5975

[01310040231]

Our 5975 was working fine until the filament burnt. Filaments changed and source was cleaned. The noise level increased and the more volatile compounds (I am doing 8260) were lost at low concentration. Changed all the lines on the purge & trap; cleaned the source and HED and started getting elevated levels of 207! Cleaned the injector, replaced the liner, gold seal, and the column and 207 is still high!

Any suggestions?

Thank you.

[cleh]

How old is your column (207 is column bleed)? How is your air and H2O check? If you have a leak before the column (injector, purge and trap, gas connections, He regulator, and He purifiers) it will cause this. If the He purifier is old, it could be bad. Also, a leak can cause your filament to blow. If your using a regular septum you should replace it. If your using a Merlin Micro Seal the septum may be leaking and it may need to be replaced. If you have an electronic He detector you should check everything with that.

[01310040231]

Column and septa are brand new and there is no leak in the system.

[cleh]

Did you bake out the column before installing it in the transfer line?

[01310040231]

I did bake the column.

[cleh]

It sounds like a leak, but you seem to have ruled that out. It may be the He purifier. You can remove it and see if there's any improvement without it. Other than that, you may want to bake your column a little more (as long as you're positive there's no leak). It would help if you could post a chromatogram, a spectrum of the background, and your air/H2O check.