A macroporous particulate support prepared previously by reactive gelation under shear and functionalized
with poly(N-isopropylacrylamide), PNIPAM, brushes of variable length is applied for
temperature-responsive chromatography, whereby temperature modulates hydrophobic interactions.
Several different analytes, including small pharmaceuticals, peptides, proteins and monoclonal antibodies
are employed. Contrary to the most commonly observed behavior in conventional chromatography,
increasing retention is observed at elevated temperatures. Peak broadening is quantified using the peak
standard deviation, which depends on both the polymer chain conformation and analyte adsorptivity.
The favorable effect of grafted polymer thickness on retention becomes progressively less pronounced
for thicker grafted PNIPAM layers. The effect of eluent composition on solute–sorbent interactions was
investigated by introducing NaCl, methanol, dioxane and by varying the pH. Salt or organic solvent addition
affects apart from the analytes solution properties, the hydrophobicity of the stationary phase itself.
Frontal analyses performed at different temperatures to determine dynamic binding capacities, indicate
small mass transfer resistances imposed by this novel packing material.