IC System Problems

[heath_v]

Hi,

I am hoping someone can give me some ideas on a problem I am having with IC. I am running a method in anion mode with a CarboPac column using an electrochemical detector (Pulsed Amperometric Detector). I am seeing a lot of interference in my chromatogram where the baseline is flying from very low to very high values randomly over a period of 3-5 minutes. I have seen something similar in the past when the system had got air in it, but this time is different. The system seems to run ok, and then this problem reappears for no apparent reason and then takes a long time to settle down. I am pretty sure that no air is being pulled into the system through the lines. Does anyone have any ideas what could be causing this problem?

Thanks.

[Markus Laeubli, Metrohm]

I can imagine eluent contamination, working electrode contamination, reference electrode problem e.g. no contact.

[John Guajardo]

Is your system pressure steady or does it fluctuate with the baseline? Have you tried "burping" the cell in case there's an air bubble trapped in it? It might also be a good idea to disassemble the cell, rinse off the surfaces with DI water (maybe consider replacing the gasket and/or disposable working electrode), and reassemble the cell.