Immobilized metal-ion affinity chromatography: Imidazole proton pump and chromatographic sequelae. II. Chromatographic sequelae

Isocratic elution with imidazole of some protein models from a chelating gel, CSFF–IDA–M(II), resulted in their desorption owing to the low pH (6→4) of the mobile phase rather than to the imidazole itself (imidazole‐generated fall in pH; proton pump). Gradient elution with imidazole was best accomplished when the chelating gel was initially converted into its imidazole complex, CSFF–IDA–M(II)Im. The exploitation of the imidazole‐generated proton pump in the IMAC of proteins may enhance the versatility of this type of chromatography.