Concept of temperature-responsive chromatography: (a) hydration and dehydration of grafted polymer under an external temperature change ((i) hydrated, expanded PIPAAm and (ii) dehydrated, shrunken PIPAAm), (b) hydrophobic interaction with analyte and (c) chromatograms ((i) 5°C and (ii) 35°C) of steroid analytes separated on PIPAAm-grafted silica beads. Peaks: 1, benzene; 2, hydrocortisone; 3, prednisolone; 4, dexamethasone; 5, hydrocortisone acetate; 6, testosterone. Adapted from Kanazawa et al. (1996). Copyright 1996, American Chemical Society.