high cell current
Posted: Thu Jul 02, 2009 11:07 pm
Hello,
After hours with our HPLC system, in the corresponding manuals and on the internet, I give up. After around 1 month of daily but not intensive use, the pressure and the cell current started to increase and the baseline became noisy.
I first changed the mobile phase for a fresh one. No improvement.
We changed the pre-column, and now the pressure is "normal". (yeah)
I cleaned, then polished the reference and working electrode and coated the reference electrode with its reference electrode solution.
I paid attention to bubbles and not to tight too strong the bolts when I reassembled the flow cell.
I checked bubbles everywhere t is visible on the system.
I performed an electrochemical cleaning of the working electrode by applying pulses of +1 to -1V during 10 min (I know I should have tried this before polishing)
I added more EDTA (it is now 0.1g/L, around 0.2mM) into the mobile phase.
But nothing had neither a positive nor a negative effect.
The screen displays an Icell = +66 nA!!!
(other settings are range NA, Eox=+0.65V, range 20 nA, Offset 0%, Filt. 2s)
The noise of the baseline is of course a problem (I would say it is a regular noise, but the baseline drifts up from time to time) but my concern is more the high cell current. I could not find anything about this issue on the internet whereas I have a list of potential causes of the noise and possible solutions.
Does anyone know? Could anyone explain me a bit about it: what can cause the Icell to increase (decrease?), what can I do to correct it?
Thanks a lot in advance for any information, I feel so alone!
After hours with our HPLC system, in the corresponding manuals and on the internet, I give up. After around 1 month of daily but not intensive use, the pressure and the cell current started to increase and the baseline became noisy.
I first changed the mobile phase for a fresh one. No improvement.
We changed the pre-column, and now the pressure is "normal". (yeah)
I cleaned, then polished the reference and working electrode and coated the reference electrode with its reference electrode solution.
I paid attention to bubbles and not to tight too strong the bolts when I reassembled the flow cell.
I checked bubbles everywhere t is visible on the system.
I performed an electrochemical cleaning of the working electrode by applying pulses of +1 to -1V during 10 min (I know I should have tried this before polishing)
I added more EDTA (it is now 0.1g/L, around 0.2mM) into the mobile phase.
But nothing had neither a positive nor a negative effect.
The screen displays an Icell = +66 nA!!!
(other settings are range NA, Eox=+0.65V, range 20 nA, Offset 0%, Filt. 2s)
The noise of the baseline is of course a problem (I would say it is a regular noise, but the baseline drifts up from time to time) but my concern is more the high cell current. I could not find anything about this issue on the internet whereas I have a list of potential causes of the noise and possible solutions.
Does anyone know? Could anyone explain me a bit about it: what can cause the Icell to increase (decrease?), what can I do to correct it?
Thanks a lot in advance for any information, I feel so alone!