Waters alliance 2695 ran dry, now poor peak response

[jtoshea2005]

This system ran dry overnight. Its a 2695 connected to a 2475 FLD. Despite a new column, dry and wet primes, I still see about 1/100th peak response. (very low)
I purged injector, ran IPA through system and still no luck. I injected a standard on a 2487 UV which displayed a good peak response. But when I connect the 2475 FLD, it still has poor peak response? What compound can I inject on the FLD for a quick evaluation. ( i can't inject UV compounds like acetone and caffeine, like on the 2487)

any suggestions?
Also, can my original column be revived?

thanks

[juddc]

Have you tried removing the column, slowing down the pump, and just injecting a std into the detector to see if you have a peak?

Tryptophan may be a good compound to detect on your 2475...Ex 278, Em 355, I think. As far as the loss of response, it sounds like it could be a coincidental failure of the detector. I have an old 474 that is generally quite reliable, but has been known to fail completely and without any warning. It's done this twice, once in the middle of a run where the prior injection looked perfect and the following run was just baseline. Both times required shipping back to Waters for rebuilding. As expensive as it is, I won't run an FD without a service contract.

[jtoshea2005]

thanks for the info. I got the air out of the fld by pumping IPA at a low flow rate. I saw synchrounous baseline noise (spikes) so I knew it was the pump. Changed the check valves and all good now.