SizeSep - XP is a phase coated with hydrophilic and neutral lying-down monolayer films which chemically bond on porous silica. Similarly to SizeSep-X, particle sizes of 3µm and 5µm and pore sizes of 100, 150, 300, 500, 1000, and 2000Å provide typical particle size selection and widest pore size selection for separation and analysis of hydrophobic proteins like insulin, membrane protein monoclonal antibodies derivatized with polymer branches, e.g. polypeptide and PEG.