Chromatography Forum

I am fairly new to LC, so forgive me if my question is rudimentary. I have read that switching on your UV lamp without any flow can be harmful to your lamp. If this is the case, can someone explain exactly how this can cause damage? And is this the case with all systems coupled to UV detectors, or does it depend on your instrument?
Many thanks.

..." I have read that switching on your UV lamp without any flow can be harmful to your lamp. "....

Where have you read that ?
It won't be harmfull to lamp.
But UV lamp generates heat causing increase of temperature in the flow cell. That's why mobil phase should flow through the cell when UV lamp is on.

Thanks for your reply. Ah, perhaps that is what I have read, that it can damage the flow cell. So is this always the case and you should never have your lamp on without flow, or is it not really an issue?

UV lamps have finite lifetime , mostly 1.000 hours ( or 2.000 hours for longlife types ), so it is better to switch the detector off , if it is not in use.

Hey Esar88,

I'm with these other fellows; stopping flow while leaving the UV detector "On" in a HPLC instrument won't damage either the lamp. No such a thing as a question which is "rudimentary", either. Always it is better to know than not to.

It's my understanding that turning on/off UV lamp frequently can shorten the UV lamp life also. So turn it off only when it's not going to be used for fairly long period of time, such as overnight.

Its true that there is no damage in this issue but I remember I had some problem with waters 2487 dual absorbance UV detector ,I had repeated autocalibration errors at some wavelength and I found that it was because of little air bubbles in flow cell so I had to keep the flow running for while to discard this air bubbles and it worked