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Thermo Fisher Scientific

IC OQ - ED Noise and Drift Test Failing


As part of an IC OQ, the Electrocehmical Detector (ED) Noise and/or Drift test is failing.


  • Qualification (OQ)
  • ICS-6000
  • ICS-5000
  • Electrochemical Detector (ED)


First Confirm:

  • Instrument Method is correct (Waveform, Flow Rate, Temperatures, Data Collection Rate)
  • Adequate time for equilibration was given, ED can require 12 hrs to fully equilibrate
  • Tubing is correct and not overly restriciting or leaking (System Pressure is ~1500 psi for Analytical Pumps)
  • The 2M NaOH system rinse has been performed to clean the system
  • Quality of Eluent (If manually prepared: Water degassed prior to eluent prep,  50mM prepared from 50% w/w NaOH, preferably a new unopened bottle)

To Help with ED Noise:

  • Re-Run the 2M NaOH system rinse  (30 mins), followed by DI Water rinse (30 mins)
  • Prepare new Eluent (if applicable)
  • Add additional Yellow capillary between restrictor and guard column to increase system pressure appropriately
  • Reconnect test cell cable to amperometry cell connection on SP board
  • Replace DWE, reference electrode or electrochemical cell

To Help With ED Drift:

  • Prepare new Eluent (if applicable)
  • Remove detector Autozero from instrument method
  • Regulate lab temperature if possible (block vents, close windows, etc.)


The ED is highliy sensitive to laboratory HVAC conditions, and requires the system to be clean and properly equilibrated.

See ED User Compendium for more details: 065340 - Rev - 02 ED User Compendium


The following causes contribute to ED Noise and Drift:

  • System not equilibrated
  • Electrochemical cell not connected properly or defective
  • System not clean
  • Eluent quality bad
  • Lab temperature not stable (HVAC interference)


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