Abstract: A material for reverse phase chromatography comprises surface modifying apolar and charged groups bound to a solid support, said charged groups being present in amounts of about 0.25 to about 22% of the surface modifying groups, or in amounts of about 0.01 ?mol/m2 to 0.8 ?mol/m2 referred to the surface of the solid support for a material with a total amount of surface modifying groups of 3.6 ?mol/m2. Such material and suitable purification conditions for active pharmaceutical ingredients (APIs) like peptides can be evaluated by (a) determining the isoelectric point (pI) of the API of interest, (b) choosing a pH in a range where the solid phase material is stable, (c) determining the difference pI?pH and (d) if the difference pI?pH is positive, choosing an anion exchange (AIEX) material, or if the difference pI?pH is negative, choosing an cation exchange (CIEX) material.

Abstract: A material for reverse phase chromatography comprises surface modifying apolar and charged groups bound to a solid support, said charged groups being present in amounts of about 0.25 to about 22% of the surface modifying groups, or in amounts of about 0.01 ?mol/m2 to 0.8 ?mol/m2 referred to the surface of the solid support for a material with a total amount of surface modifying groups of 3.6 ?mol/m2. Such material and suitable purification conditions for active pharmaceutical ingredients (APIs) like peptides can be evaluated by (a) determining the isoelectric point (pI) of the API of interest, (b) choosing a pH in a range where the solid phase material is stable, (c) determining the difference pI-pH and (d) if the difference pI-pH is positive, choosing an anion exchange (AIEX) material, or if the difference pI-pH is negative, choosing an cation exchange (CIEX) material.