HPLC DAD FL noisy baseline

[carls]

I am not aware of a reason why removing the cell with the lamp on would damage the lamp. This is part of Agilent's standard test when troubleshooting their UV detector and I have done this many times on other UV detectors as well. I do not remember having to do this with a fluorescence detector but I cant imagine why it would damage the lamp.

What is the make and model of this detector?

There should be a troubleshoting section in the owners manual if you have it.

[AMY2242]

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[HW Mueller]

In my suggestions I assumed that you did the obvious and did the checks of the optical light paths that probably all detectors provide.
If you have fines in there water flushing might help (best in alternation with alcohol), I have not heard of a cell that can not withstand the pressure one can attain with a syringe (maybe a 1 mL syringe could come close??). You might even have to use the pumps to get enough flow. It seems that I have heard that someone took the cell apart to clean it, I never needed that.
What about the fluorescence detector?

[AMY2242]

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[HW Mueller]

As pointed out before and elsewhere, the best way is to systematically find the cause, not using wild actionism. We finally found out that the fluorescence baseline is also noisy, but you don´t tell how the relationship of the noise is to flow (including different flow rates) vs stop flow, syringe flows done by hand, different solvents, column and no column, first of all the detector self test (for instance how does the water Raman look in the fluo. det.?), what highly degassed solvents do (in my hands the strongest degassing is obtained via vacuum, not easy to keep degassed while getting it into the cell).

[agnese]

You mentioned that your system run out of mobile phase- running pump dry could do damage to check valves and seals; malfunctioning check valves can give quite noisy baseline.