Fluorescence-signal 35 times to low Waters 2475

[HW Mueller]

Are you sure that you didn´t just have an air bubble problem?
Especially when using fluorescence detection one should be familiar with the apparatus, one should know that it would be senseless to do a water Raman line test without water and without the cell. The Raman line test should have a very good S/N now, if the increase in signal is real. Also, the Raman line test should be performed frequently if you want to prevent unpleasant surprises.

[bisonium]

HW Mueller, we at first thougt of the posibility to have a bubble trapped. But since the detector was washed with acetic acid, 1M NaOH, 20%EtOH and also flushed with lots and lots of MilliQ purified unionized water (for atleast 7 days in a row), the posible bubble problem should be eliminated?
The problem is that "no one" uses the W2475 detector, or atleast no one has experienced the 35 times signal loss. I hope the problem was something thas was trapped inside the detector.

Danko, almost every little part of the detector was exchanged, including the lamp (twice), the motherboard, the battery and the front panel board. I think that electrical connection cant be the problem since the signal (even if it was way too low) was very stable during the whole time of investigation.

I hope it-ll work fine now, at least the coming two weeks; I have quite a lot of analyses to perform with the mashine.

[HW Mueller]

If you have an air leak somewhere in the system it doesn´t help to flush with zillions of solutions, you still get the air in.
Sometimes a necessary replumbing eliminates air leaks inadvertendly, maybe that´s what happened in your case?

[bisonium]

Yeah, you are right there offcourse. Say, wouldn´t I have noticed some kind of Pressure stability fluctuations if having a leak?

/Mattias

[HW Mueller]

A constant leak after the pump wouldn´t be registered, you wouldn´t even see it as a lowering of flow (the leak would be very small if it went undetected). It is even imaginable that there was no leak but a insufficient degassing.

[bisonium]

Thanks, I'll have that in mind as I troubleshoot further more. I got still one week to go, then vacation.