Signal from HPLC-ECD is suddenly capping at 1000 nA?

[rycar88]

Hello,

I have recently ran into a problem where the signal response on all peaks from our ECD is capping at 1000 nA. The peak RTs and general shape are otherwise normal, they just look like they are decapitated to form a horizontal response at 1000. (This is also true of response in the cell cleaning runs...)

Does anyone here know how I can fix this? Is it just a matter of polishing a dirty electrode, or replacing it?

The cell model is the Thermo Dionex 6041RS if that helps.

[vmu]

Is it just a matter of polishing a dirty electrode, or replacing it?

It's a matter of detector overload.
Reduce the amount of sample injected to the column.

[rycar88]

There were a few survey samples that most likely saturated the system/detector. However, historically this method has easily gone above 1000 nA with no problems. Normally our top calibration point has a peak height of ~3000 nA. Our range will be severely limited if we have to keep responses <1000 nA.

Is there a way to fix the detector/electrode to return it to the working response range it had before?

[vmu]

You may try to polish the electrode before you decide to replace it. Also check the instrument configuration for any unnoticed changes, e.g. changes in the signal multiplier in the ECD configuration window. Try to find help here:
Electrochemical Detector ECD-3000RS
Operating Instructions
https://assets.thermofisher.com/TFS-Ass ... 001-en.pdf