Editing Anion Exchange Column Regeneration (section)

== Regeneration ==

The following procedure should be satisfactory to remove common contaminants:<br/>1. Wash with 2 column volumes of 2 M NaCl at 0.2 ml/min.<br/>2. Wash with 4 column volumes of 1 M NaOH at 0.2 ml/min.<br/>3. Wash with 2 column volumes of 2 M NaCl at 0.2 ml/min.<br/>4. Rinse with at least 2 column volumes of distilled water at 0.2 ml/min until the UV-baseline and elutent pH are stable.<br/>5. Wash with at least 4 column volumes of start buffer or storage buffer at 0.2 ml/min until pH and conductivity values have reached the required values.<br/>

If back pressure remains high, change top filter.

<br/>Save time by monitoring any cleaning procedure to check for elution of contaminants.&nbsp; Depending on the nature of the contaminants, the following cleaning solutions can also be used: 100% isopropanol, 20% acetonitrile, 2 M NaOH, 75% acetic acid, 20% ethanol, 100% methanol or up to 6 M guanidine hydrochloride, cationic or non-ionic detergents.

<br/>Always rinse with at least 2 column volumes of distilled water after using any of these cleaning solutions. When using organic solvents, wash the column using sawtooth gradients e.g. run from 0–100% solvent in 5 column volumes then from 100–0% in 5 column volumes, including 1% trifluoroacetic acid in the water and organic solvent. If column performance is still not restored, inject a solution of 1 mg/ml pepsin in 0.1 M acetic acid containing 0.5 M NaCl and leave overnight at room temperature or one hour at 37 oC. 

<br/>Depending on the contaminant, other enzymes may also be used, e.g. DNase. After any enzymatic treatment, repeat the steps to remove severe contamination described previously.