Preparative chromatography theory

Contemporary development of chromatography theory has tended to concentrate on dispersion in electro-chromatography and the treatment of column overload in preparative columns. Under overload conditions, the adsorption isotherm of the solute with respect to the stationary phase can be grossly nonlinear. One of the prime contributors in this research has been Guiochon and his co-workers, [27-30]. The form of the isotherm must be experimentally determined and, from the equilibrium data, and by the use of appropriate computer programs, it has been shown possible to calculate the theoretical profile of an overloaded peak. 

Keywords Preparative chromatography, Simulated moving bed chromatography, Continuous separation technique, Triangle theory, Bioseparation... 

The process is now well understood, as has been demonstrated by its successful modeling under a wide variety of experimental conditions and the excellent agreement observed between the model predictions and the experimental results [131, 132], The theory of preparative chromatography is essentially complete nevertheless, further improvements are to be expected. The important unsolved issues that remain so far have been summarized by Guiochon [133] as follows They are (i) in the thermodynamics of equilibrium ... 

The fundamental problems of nonlinear chromatography and the theory of preparative chromatography have been the topic of intense activity by chromatogra-phers and chemical engineers. Each community has largely overlooked the activities, as well as the preoccupations and viewpoints, of the other one. Furthermore, this activity did not start abruptly and is not entirely finished. Theoretical problems in nonlinear chromatography have been discussed in the literature for more than 50 years and some are still today. Some of these works have been quite influential in some circles, while they were completely ignored in others. 

A good description of all important areas of preparative layer chromatography, theory and a wide range of applications (e. g. the use of PLC for isolation and identification of unknown compounds from the frankincense resin (Ohbanum), strategies for finding marker substances). 

The mathematical description of the preparative chromatography is based on the adsorption theory [41-43] and the theory of nonlinear chromatography [44]. 

See also Air Analysis Sampling. Chromatography Overview Principles. Clinical Analysis Sample Handling. Drug Metabolism Metabolite Isolation and Identification. Extraction Solid-Phase Extraction. Food and Nutritional Analysis Sample Preparation. Forensic Sciences Volatile Substances. Headspace Analysis Purge and Trap. Perfumes. Sample Handling Sample Preservation Automated Sample Preparation. Sampling Theory. 

Conway, W.D. Countercurrent Chromatography Apparatus, Theory, and Applications-, VCH New York, 1990. Hostettmann, K. Hostettmann, M. Marston, A. Preparative Chromatography Techniques Applications in Natural Product Isolation , Springer-Verlag Berlin, 1986. 

Preparative chromatography involves theory of some sort in almost every aspect, whether it is for calculation of the performance of a column to determine if it is sufficiently well packed for prolonged use or for a full optimisation. Very often calculations are made to determine the column and particle dimensions which allow operation of a separation at the maximum operating pressure of the equipment to maximise the production from the column. Overloading usually is more controllable if one knows the saturation capacity of the column, since this can allow at least approximate calculation of the appropriate load to try in a separation. Once the sample... 

Golshan-Shirazi, S. and Guiochon, G., Theory of optimization of the experimental conditions of preparative liquid chromatography optimization of column efficiency, Anal. Chem., 61, 1368, 1989. 

CEC is a miniaturized separation technique that combines capabilities of both interactive chromatography and CE. In Chapter 17, the theory of CEC and the factors affecting separation, such as the stationary phase and mobile phase, are discussed. The chapter focuses on the preparation of various types of columns used in CEC and describes the progress made in the development of open-tubular, particle-packed, and monolithic columns. The detection techniques in CEC, such as traditional UV detection and improvements made by coupling with more sensitive detectors like mass spectrometry (MS), are also described. Furthermore, some of the applications of CEC in the analysis of pharmaceuticals and biotechnology products are provided. 

In previous chapters, liquid chromatography column theory has been developed to explain solute retention, band dispersion, column properties and optimum column design for columns that are to be used for purely analytical purposes. The theories considered so far, have assumed that solute concentrations approach (for all practical purposes) infinite dilution, and, as a consequence, all isotherms are linear. In the specific design of the optimum preparative column for a particular preparative separation, initially, the same assumptions will be made. 

Because of the similarities in the theory and practice of these two procedures, they will be considered together. Both are examples of partition chromatography. In paper chromatography, the cellulose support is extensively hydrated, so distribution of the solutes occurs between the immobilized water (stationary phase) and the mobile developing solvent. The initial stationary liquid phase in thin-layer chromatography (TLC) is the solvent used to prepare the thin layer of adsorbent. However, as developing solvent molecules move through the stationary phase, polar solvent molecules may bind to the immobilized support and become the stationary phase. 

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