Dionex ICS-3000 baseline issue

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My baseline for my ICS-3000 looks like this.

Last time I ran conductivity, it looked fine (2 months ago). I have been running using an ECD and switched over Sunday.

I spoke to technical service and did all the typical troubleshooting steps
-replacing the detector
-New water source
-replacing the suppressor
-cleaning the cr-atc
-used both detector sides

(we also replaced the TEC board with a new one)

He would like us to schedule a service call, but has no idea what they might look at.....


We are running with a KOH gradient/cr-atc/as-11HC/supressor/crd-200/conductivity detector and are looking for different acids.
Hi Jesterrose,

  • If you acquire the pressure channel at the same time, do you see corresponding changes in the pressure baseline?
  • What is your normal operating pressure and flow rate?
  • Are you degassing your DI water before putting it on the IC system?
  • Have you primed the pump thoroughly, at least 5 minutes for each channel (100% A, then 100% B, etc.)?
  • How many backpressure coils do you have installed between the conductivity detector cell outlet and the suppressor regen in?
  • How does the baseline look if you run your DI water from the pump outlet directly into the conductivity cell inlet (bypassing all consumables) at 1 mL/min? You may need to temporarily install a piece of yellow backpressure tubing between the pump outlet and detector cell inlet to ensure the pressure stays above 200 psi during this test.
Best regards,

John Guajardo
Product Manager, IC Columns
Thermo Fisher Scientific
The pressure is stable. Running isocratic with degasser water. I did prime it thoroughly (set it to rin 30 min) but will sonnicate longer.

My pressure is right at 2500 psi at 1 ml/min.

It is in external Regen mode so I have no back pressure coils installed as the detector goes to waste.

I will buy pass the system again with this new detector and see what it looks like.
Thanks for that info. I would also recommend installing one backpressure coil (p/n 045877) at the detector outlet and see if things improve. See section 2.4 and 3.4 of the suppressor operators manual for more info:

http://www.dionex.com/en-us/webdocs/114493-Man-ERS-500-Suppressor-031956-09.pdf
Best regards,

John Guajardo
Product Manager, IC Columns
Thermo Fisher Scientific
You said you're using an ECD but it's actually a CD right? Are you using an EG? If so maybe the EG degasser is bad. The 3000 has a separate degasser in the module. It appears that you get more noise spikes at higher KOH on the baseline, which is where there is more gas generated.
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