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Thermo Fisher Scientific

Rise in baseline during a gradient

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Issue

I am using KOH RFIC with an application that has a gradient, but I am seeing large baseline rises during each run, what could be causing it? 

Environment

Ion Chromatography

Resolution

CR-ATC Cleanup:

The CR-ATC for normal day-to-day operation does not require a cleanup. However, if the CR-ATC is exposed accidentally to high levels of anionic contaminants or is converted to the -OH form to other anionic forms such as carbonate, the device requires a cleanup using 2.0 M NaOH.

  1. Disconnect all lines to the CR-ATC.
  2. Connect a line from the Eluent In port to the Regen In port on the CR-ATC. Direct the Regen Out port to waste.
  3. Prepare a fresh solution of 2.0 M NaOH from a 50% w/w NaOH solution.
  4. Use the trap column/suppressor clean-up kit (P/N 059659) to deliver 100 mL of 2.0 M NaOH solution through the Eluent Out port of the CR-ATC column, or 10 mL to a CR-ATC capillary column.
  5. Rinse the CR-ATC unit with 10 mL (1 mL for CR-ATC capillary columns) DI water before plumbing it back to the system.

Cause

The Dionex CR-TC is most likely contaminated. Clean the trap column as instructed in the Dionex CR-TC manual. The manual is provided on the Thermo Scientific Reference Library DVD (P/N 053891).