UV Signal just seems to be drifting

[sga]

Hello all,

I am trying to requalify my 1100 with a UV DAD detector which has been lying idle for some time. The UV signal seems to be just mandering around betwen ±50 mAV and even though I have balanced the signal many times the baseline just does not seem to stabelise. Almost a sinusoidal wave.

Any idea what could be causing this ?

I have tried to inject Caffeen a few times to get a peak, but this also does not seem to be helping. No peak observed nothing.

[Gerhard Kratz]

I guess your flow cell makes the problem, dirty, air bubbles, I would recommend first to rinse the flow cell and purge carefully with a syringe. Isopropanole to rinse is good. Good luck.

[tom jupille]

Do you see the same drift / wander with no flow?
And if it looks somewhat "sinusoidal" does the period change when you change the flow rate?
And does the problem vary with wavelength?

[Steve Reimer]

How many hours on the lamp?
How long has it been on?

[BostonFSE]

observe the flow on the live plot then turn the flow off. If the baseline goes flat you have a dirty flow cell. If the baseline stays "wavy" you have a bad lamp
both are simple to replace but cost over $1000 each
Lamps are usually rate to 2000 hours or so