Comparison of the results obtained with different models for the simulation of preparative chromatography

“…Symbols and lines same as in Figure 6. equilibrium model and the finite difference algorithm, previously used to calculate the solutions of this model because its computing time is much shorter (Czok and Guiochon, 1990). For reasons discussed elsewhere (Golshan-Shirazi and Guiochon, 1992b), this third profile is slightly steeper than the one obtained with the finite element method.…”

Section: Aq = L66mentioning

confidence: 92%

The Thickness of Shock Layers in Liquid Chromatography

Zhu¹,

Ma²,

Guiochon³

1993

Biotechnology Progress

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At high concentrations, one boundary (the front if the isotherm is convex upward) of the elution band of a single component becomes very steep. Similarly, in frontal analysis, the same boundary is self-sharpening. These steep boundaries are called shock layers. They result from the steady-state equilibrium between a nonlinear thermodynamics of phase equilibrium on the one hand, which tends to create a concentration discontinuity, and axial dispersion and a finite rate of mass transfer on the other hand, which tend to relax the concentration gradient. We show that the width of experimental breakthrough curves recorded in frontal analysis agrees well with the prediction of the shock layer theory of Rhee and Amundson in the high concentration range. It is a function of the coefficients of the column HETP equation and the height of the concentration step and is independent of the column length, after the steady state is achieved. In the low concentration range, a discrepancy is observed when the column length is short and the migration distance is insufficient to achieve constant pattern behavior.

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“…1 with 0, = 0 (ideal model). The values of the time and length increments of the integration are chosen to provide a numerical dispersion exactly equal to the desired apparent dispersion (Czok and Guiochon, 1990).…”

Section: Band Pro File Calculationsmentioning

confidence: 99%

Optimizing experimental conditions for minimum production cost in preparative chromatography

Felinger

Guiochon

1994

AIChE Journal

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In trod uc t ionThe optimization of the experimental conditions in preparative liquid chromatography is a topic of serious current concern (Colin, 1993a). This is due to the growing interest of the pharmaceutical industry for this new separation method which permits the purification of significant amounts of drug intermediates, peptides, or proteins by eliminating closely related, but unwanted, compounds. While at the research and development level the actual preparation cost is often a minor fraction of the total cost of the project, in production new perspectives are introduced. This requires that the optimization of the experimental conditions should achieve the lowest possible production cost. This cost includes contributions of capital (such as chromatograph, pumps, tubings and valvings, and building), operating (solvents, stationary phase, raw material lost, and energy), and labor. It is difficult, however, to account for all the cost contributions in the design of a new separation method, especially with a new process like liquid chromatography. Accounting procedures vary widely from company to company, if not within divisions of a large company. For example, overhead may constitute a large fraction of the total costs, and it is calculated following rules specific to each com-

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Comparison of the results obtained with different models for the simulation of preparative chromatography

Cited by 31 publications

References 32 publications

Isotherm selection for band profile simulations in preparative chromatography

Isotherm selection for band profile simulations in preparative chromatography

The Thickness of Shock Layers in Liquid Chromatography

Optimizing experimental conditions for minimum production cost in preparative chromatography

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