IMAC: nonlinear elution chromatography of proteins

Nonlinear elution chromatography of proteins employing the traditional mobile phase modulators in IMAC has been studied using the metal affinity interaction model (MAIC) in conjunction with the chromatographic mass transport equations. Results indicate that when the feed is loaded under conditions that foster constant pattern formation, isocratic elution leads to Langmuirian profiles at low mobile phase modulator (MPM) concentrations and a double-plateau profile at high concentrations. A non-self-sharpening protein front during loading, on the other hand, can lead to three plateau profiles or peak splitting and ghost peak formation. Experimental and simulation results on protein separations employing high-affinity modulators suggest that elution with loading in the absence of modulators leads to considerably higher throughputs and protein concentrations due to the displacement effects of the modulator as it migrates through the protein zones. Also, for certain separation problems, the operating conditions can be chosen such that the complex modulator system peaks manifest themselves as spacer displacer; affecting a sharper rear of the earlier eluting protein and an efficient separation. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54:373-390, 1997.