Chromatography Forum

Dear everyone,

I have a problem with my HPLC RI system, (both with SE, eluent water with 0,3% NaCl; and NP, eluent water).
The baseline seems to be steady before the run, and during every single run the baseline jumps 5-10 times from 0 to -50..-80 µRIu



https://docs.google.com/file/d/0B4f2VbJ ... VjeU0/edit

Thanks for any help!

Dear everyone,

I have a problem with my HPLC RI system, (both with SE, eluent water with 0,3% NaCl; and NP, eluent water).
The baseline seems to be steady before the run, and during every single run the baseline jumps 5-10 times from 0 to -50..-80 µRIu. The pump pressure and oven temperature are both stable and okay.

Here is how it looks:

https://docs.google.com/file/d/0B4f2VbJ ... VjeU0/edit

Thanks for any help!

Air bubble in the flow cell?
Problems with the reference cell?

PeterS

Thank you very much, I have tried one hour detektor purge with methanol now, and its not better, so I guess flow or reference cell contamination or air bubbles can be excluded...

Any other ideas?

That link didn't work (page not found).

However, spikes that occur only during a run are usually symptomatic of air bubbles (or, far less common, particles making their way out of the column).

Hello,

Maybe flushing with methanol is not enough. Years ago we had similar problems and we had to wash the cell with 1M NaOH, water and propanol.
Then our signal became stable.

PeterS

Dear everyone,

I have a problem with ...

And the question is why you ask about HPLC in GC forum ?

Thank you very much for the reply, but it does not look like air bubbles.

This looks like: the baseline is on zero for 10 min, than on - 50 uRIU for 5 min, than back to zero, than -80 uRIU for 7 minutes again, back again, and so on, and so on.

Thanks for any help!

Okay, thanks for the advice, I'll try it. But it really doesn't look like air bubbles, because when the basline drops dramatically to - 50 uRIU it also stays there for 5-10 minutes, and only than returnes to zero.



ps: To answer Mr. Proper as well: Of course it was by accident, that I have used the GC forum at first, but apparently it was a good choicce: I have got more answers by now, than on the HPLC forum.



Thanks

Threads now merged in appropriate forum.

...
apparently it was a good choicce: I have got more answers by now, than on the HPLC forum.

Anna, it wasn't. You simply violated forum rules. If you were more patient and waited one or two working days you would get answers in HPLC forum without the need of "cleaning" by Mod.

OK, dear, I was joking by saying: "it was a good choice", because in the same sentence I have already told that it was by accident.

I really feel offended by being charged with violation of the rules, and having to apologize for so many times about an obivously unintended and ridiculously small-scale mistake.

So I say thank you to those who were helping, and I say farewell to this forum.

Anna