Core-Shell Mixed-Mode Stationary Phases


SIELC Technologies developed mixed-mode Columns based on solid-core-porous-shell particles. This separation media combines the efficiency of core-shell technology with the unique selectivity of Ion-Exchange (IE) reverse phase (RP) surface chemistry and ion-exchange HILIC surface.

Combination of solid core particles and IE with RP or HILIC chemistry offers:

  • fast separation
  • working pressure within limits of conventional HPLC
  • unique selectivity profile
  • retention of compounds difficult to retain by RP chromatography
  • increase column loading capacity
  • adjustment of selectivity by mobile phase pH, ion strength, and organic concentration and composition


Columns available in Core-Shell format with 2.7 µm particles:

Column Ion-exchange Separation mode
Primesep 100 Cation exchange RP
Primesep SB Anion exchange RP
Primesep S Cation exchange HILIC
Primesep NB Anion exchange HILIC


One disadvantage of the solid core support in HPLC is lower capacity if compare to regular through porous material. However the mixed-mode materials demonstrated much higher loading capacity compare to regular RP phases (Nicola H. Davies, Melvin R. Euerby and David V. McCalley, Journal of Chromatography A, Volume 1138, Issues 1-2, 5 January 2007,  65-72). Thus the mixed-mode surface chemistry compensates for lost of loading capacity of partially non-porous particles.

Mixed mode columns demonstrate 2D characteristics with independent adjustment of degree of retention based on ionic and hydrophobic mechanism.
Reverse phase mechanism controls by amount of organic modifier in the mobile phase.
Ion-exchange mechanism controls by ion strength and pH of the mobile phase.
This property allows to resolve complex mixtures with polar, hydrophobic, ionic, and neutral compounds.


Some separation examples: