Models for Preparative Chromatography

G. Guiochon and B. Lin, Modelling for Preparative Chromatography, Academic Press, Amsterdam, 2003. 

Guiochon, G., Lin, B. Modeling For Preparative Chromatography, Academic Press, London, 2003. 

Figure 2.5 Illustration of the Danckwerts Boundary Condition. 1 Rectangular pulse injection. 2, 3,4 Danckwerts injection conditions for the same sample amoimt 2 D = 0.04 cm /s 3 D = 0.08 cm /s 4 D = 0.12 cm /s. Reproduced with permission from G. Guiochon, B. Lin, Modeling for Preparative Chromatography, Academic Press, San Diego, CA, USA, 2003 (Fig. III-2).

Guiochon, G. and Lin, B. (2003) Modeling for Preparative Chromatography, Elsevier, Amsterdam. 

For preparative chromatography, where we almost always have to deal with high feed concentrations and nonlinear adsorption isotherms, the following approach to the appropriate choice of feed concentration during model-based optimization is recommended ... 

The second row in Equation 6.143 represents the famous Van Deemter equation (Equation 2.42) and shows how the model parameters A, B, and C are related to Dgx and keff. For preparative chromatography the B term can be often neglected (Section 6.S.6.2). 

Time, Cost, and Equipment Analysis time can vary from several minutes for samples containing only a few constituents to more than an hour for more complex samples. Preliminary sample preparation may substantially increase the analysis time. Instrumentation for gas chromatography ranges in price from inexpensive (a few thousand dollars) to expensive (more than 50,000). The more expensive models are equipped for capillary columns and include a variety of injection options and more sophisticated detectors, such as a mass spectrometer. Packed columns typically cost 50- 200, and the cost of a capillary column is typically 200- 1000. 

The coupling of supercritical fluid extraction (SEE) with gas chromatography (SEE-GC) provides an excellent example of the application of multidimensional chromatography principles to a sample preparation method. In SEE, the analytical matrix is packed into an extraction vessel and a supercritical fluid, usually carbon dioxide, is passed through it. The analyte matrix may be viewed as the stationary phase, while the supercritical fluid can be viewed as the mobile phase. In order to obtain an effective extraction, the solubility of the analyte in the supercritical fluid mobile phase must be considered, along with its affinity to the matrix stationary phase. The effluent from the extraction is then collected and transferred to a gas chromatograph. In his comprehensive text, Taylor provides an excellent description of the principles and applications of SEE (44), while Pawliszyn presents a description of the supercritical fluid as the mobile phase in his development of a kinetic model for the extraction process (45). 

Kaltenbrunner, O. and Jungbauer, A., Simple model for blending aqueous salt buffers. Application to preparative chromatography, /. Chromatogr. A, 769, 37, 1997. 

Reverse-phase HPLC procedures for vitamin D3 in bulk drug were reported in the early 701s by William et al. (54) using a DuPont Permaphase 0DS column (DuPont, Wilmington, Del.) and 78% methanol in water as the mobile phase. A similar column and mobile phase (DuPont s Zorbax 0DS Column and 95% methanol in water) were reported to give increased resolution of the two forms of vitamin D (62) in multivitamin formulations. Complete separation of vitamins Dg and D3 by reverse-phase chromatography in model multivitamin preparations were reported by Osadca and Araujo (63). In this... 

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