Process variables, preparative chromatography

Whatever the approach selected, in order to optimize a nonlinear, preparative chromatographic system, one needs to consider four different factors, the objective function selected, the experimental parameters that can be optimized, the decision variable, and the constraints that must be satisfied [1]. The objective functions are discussed later, in Section 18.2.2). They include the production rate, its cost, the recovery )deld, the specific solvent consumption, or some combination of the above. Many experimental parameters of a preparative chromatography separation cannot be changed during the optimization process. Typically, such parameters are the nature of the feed components, their relative compositions, and the nature or even the brand of packing material. Sometimes, the coliunn diameter is also fixed by prior investments. The decisions variables are those parameters that can be changed during the optimization process, in order to maximize the ob-... 

Liquid/liquid partition chromatography was explored by Willstatter from 1913. The process was extensively developed by Martin and Synge (ca. 1941-1948) who partitioned amino acid derivatives between chloroform and water using precipitated silica as support for the aqueous phase. The preparations of silica were again very variable and it was difficult to prevent adsorption which interfered with the expected behavior of the aminoacids. At first methyl orange was added to the water phase to visualize the amino acids the separation of the acids then caused a red band to move down the columns. The quantitative reaction with ninhydrin was introduced by Moore and Stein in 1948 for both the detection and estimation of the amino acids. Consid-... 

Another area to be looked upon of MIPs is their sometimes moderate capacity. While many preparations are sufficient for analytical applications [5], many large-scale processes (e.g., preparatory-scale chromatography) would profit from higher capacities. Several variables, such as the amount of original template used, monomer composition, configuration of the polymer, solvent, etc. may be optimized towards preparations with enhanced capacity. Generally, the capacity of MIPs corresponds often to 1% of the initial amount of template used in the synthesis of the polymer. 

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