Multi-segmented columns

New techniques are continuing to be developed which can be expected to be used in future specialized industrial applications. Multi-segmented columns have been demonstrated for the preparative purification of urokinase. Begovichandcoworkers havedevelopedatechnique for continuous spiral cylinder purifications which allow separation of the... 

The baffle patterns in the column can be segmental (simple) up to about 4-ft diameter column, and larger columns can use a disk and donut design as in heat exchangers, or the double segmented or even multi-segmented as in the layouts discussed under bubble caps earlier in this text. 

The simulation and optimization modules are used for the simulation of various experiments and for the optimization of isocratic and gradient HPLC methods. Parameters that can be optimized are concentration of organic solvent in the mobile phase, linear and multi-segment gradient profile, pH value, temperature, type of reversed-phase column, and organic solvent. 

Since one does not know what degradation products will form, gradient elution should be used. This significantly increases the chances that degradation products which are much more polar than the parent compound will be pulled away from the solvent front and those which are much less polar than the parent will elute from the column. Often the use of a multi-step gradient is particularly beneficial. The first segment of the multi-step gradient... 

Regular flow patterns are provided by the segmented flow in a single capillary or in multi-channel microreactors. Miniaturized packed-bed microreactors follow the paths of classical engineering by enabling tridde-bed or packed bubble column operation. M ost of the microstructured multiphase reactors are at the research stage. Due to the small reaction volumes th will find their appHcation mainly in small-scale production in the fine chemical and pharmaceutical industries. 

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