After installing a (new) column the sensitivity is lost

Applies to

Electrochemical detector, HPLC with reversed phase column

Summary

Immediately after installation of a (new) column a relatively high cell current is observed, the baseline drifts continuously and is noisy. The response decreases.

Cause

Installation of a new or used column. A new column usually contains traces of contaminants from the production process. In UV methods this is not a problem, but in ECD it can contaminate the electrode and result in signal loss.

Diagnosis

The problems started with exchanging the column.

Remedy

If the cell has been connected to a new column and lost the responsiveness, then we recommend applying flow cell service (manual polishing) to remove the deposition.

Prevention

Prior to using a new column, check the manufacturer’s instructions for compatible washing solutions. Before connecting a new reversed phase column in an HPLC-ECD set-up, we recommend:

• washing out with methanol/water (20/80) or similar for 1 hr (at the application flow rate).
• washing out and equilibration with the mobile phase for at least 16 hrs (at the application flow rate). This long time of washing is especially important when the mobile phase contains an ion-pairing agent.
• let the column effluent go directly to the waste collector (no cell connected during washing).

If a column is installed that was previously used for non-EC applications, the same preventive procedure is recommended, since LC-EC conditions are usually quite different.

Read more in this KB paper…