Chromatographic modes overview

In order to achieve optimal selectivity and hence resolution of natural products in HP chromatographic separation, irrespective of whether the task at hand in analytical or preparative, the choice of the chromatographic mode must be guided by the properties of the analytes (i.e., their hydrophobicity/hydrophilicity, charge, molecular size). These attributes can often be rationalized in terms of structural features, solubility profiles, and source. A more detailed overview of existing methods that have been applied for seven classes of natural products is given in Section 9.02.5. 

An overview and discussion is given of literature methods published after 1989 devoted to the ion-interaction chromatographic determination of inorganic anions. Seventy references are quoted. Ion-interaction chromatography makes use of commercial reversed-phase stationary phase and conventional high-performance liquid chromatography instrumentation. The basis of the technique, the modification of the stationary phase surface, the choice of the ion-interaction reagent as well as the dependence of retention on the different variables involved are discussed. Examples of application in the fields of environmental, clinical and food chemistry are presented. The experimental conditions of stationary phase, of mobile phase composition as well as detection mode, detection limit and application are also summarized in tables. 1997 Elsevier Science B.V. 

This chapter starts vdth an introduction to modeling of chromatographic separation processes, focusing on different models capable to describe the dynamics of front propagation phenomena in the columns and the plant peripherals. A short introduction into numerical solution methods as well as an overview regarding methods for the consistent determination of the free model parameters, especially those of the thermodynamic submodels, is given. Methods of different complexity and experimental effort are presented. Finally, it will be illustrated that appropriate models can simulate experimental data with rather high accuracy. This validation is demonstrated both for standard batch elution and for a more complex multicolumn operation mode. 

The heart of any enantioseparation by liquid chromatography is a chiral column packed with a CSP or rarely a chiral selector immobilized on the wall of a capillary. A CSP consists of a chiral selector and an inert carrier. Both constituents are equally important for the separation performance. The chromatographic literature reports several himdreds of chiral compoimds applied as chiral LC selectors. A more or less complete overview of all materials applied as chiral selectors is impossible within the framework of this short chapter. In principle, any chiral compound possessing the ability to interact noncovalently with chiral molecules has the potential to be used as chiral selector in liquid chromatography. A chiral selector has to meet a set of characteristics that depend on the goal of the separation as well as the mode and technique used. The advantages and bottlenecks of the major classes of commercially available CSPs are summarized in Table 4.1. 

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