Acquity PDA Baseline Signal Bottoming Out (negative)

[Rob Burgess]

Hi there,

I've had this issue before, and cannot remember how to fix it. Basically the detector signal goes negative and "flat-lines", and then doesn't seem to be a way to "balance" or rectify. The signal is just staying flat at -0.0653 AU!

Can anyone offer any suggestions.

PS. Not running anything unusual: big standard water, AcN +0.0%% TFA in both lines, gradients - or trying to

[tom jupille]

All wavelengths?
Any error messages?
If you reboot the system, does the problem persist?

My first guess would be an electronic problem. The instrument should run a self-test at power on.

[aceto_81]

Maybe you started up your detector with an air bubble in the cell.
Flush the system with methanol, leave a flow through the detector and cycle power of your PDA.

Ace