Editing MEP Resin (section)

== Sample Prep<br> ==

Protein-free cell culture supernatant<br>– The synthetic iron carriers present in protein-free cell culture media may cause the resin to take on a significant brown color during loading. If this occurs or if IgG recovery is low, 10 mM EDTA may be added to the sample to reduce the formation of iron complexes. 200 mM sodium citrate may alternatively be used.<br><br>– If samples are concentrated (e.g. using UF/TFF) prior to column loading, high molecular weight iron carrier, often present in protein-free cell culture media,<br>can aggregate and accumulate on the retentate side of the UF/TFF membrane. Such aggregates can bind strongly to MEP HyperCel resin and lead to column<br>fouling. The addition of 10 mM EDTA to the sample prior to concentration will limit the accumulation of these aggregates.<br>

<br>– Tween and Triton should not be included in sample or buffers. Surfactants can interfere with the binding of protein to MEP HyperCel resin. Tween and<br>Triton can be removed from sample by using a Pall SDR HyperD resin Column (PN 20033-C001) or Pall SDR HyperD resin.<br>

<br>– Lipid supplements added to the culture medium may compete for the MEP ligand, fouling the resin and reducing binding capacity. Contact Pall technical<br>service for assistance <br>

Addition of modest concentrations of sodium chloride (&lt; 1.3 M) or other lyotropic salts (e.g., ammonium sulfate) may be required as salts increase hydrophobic interaction. In such cases, the salt concentration required will be significantly less than that employed in traditional hydrophobic interaction chromatography. Elution is accomplished by reducing the pH and/or salt. 

The column must be stored at 2-8 °C (36-46 °F) and cannot be frozen. Between runs, store the column in neutral buffer containing 1 M NaCl and<br>20% (v/v) ethanol to prevent bacterial growth.