Chromatography Forum

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.

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.

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?

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

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