Mass transfer phenomena in gel permeation chromatography

Kreveld, M.E. Van; Hoed, N. Van Den

doi:10.1016/s0021-9673(00)80979-6

Cited by 65 publications

(22 citation statements)

References 33 publications

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“…Experimental results similar to the full line in Figure 3 have been reported in HPLC of proteins (7,8,43) and in size exclusion chromatography (44,45 On the Importance of Adsorption/Desorption Kinetics.…”

Section: Performance Of Chromatographic Processes Using Permeable Parsupporting

confidence: 77%

Intraparticle Convection in Chromatographic Permeable Packings

Rodrigues

1996

ACS Symposium Series

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Permeable, "large-pore" materials are finding various applications in separation engineering as adsorbents, HPLC packings, and membranes. Intraparticle forced convection is a mass transport mechanism which, in addition to diffusive transport, can not be neglected in large-pore materials. The paper provides an historical retrospective of research work in intraparticle forced convection, stressing important and often forgotten contributions. The key concept to be retained is the "augmented" diffusivity by convection (Rodrigues et al., 1982) which explains why the efficiency of adsorptive separation processes is improved when using large-pore supports. An extended Van Deemter equation has to be applied when calculating the HETP of chromatographic columns with flow-through particles. It is shown that the effect of forced convective flow in pores is to drive the separation performance between diffusion-controlled and equilibrium limits. Experimental results for protein separation by high pressure liquid chromatography in new packing media POROS Q/M and Q HYPER D are discussed."Large-pore" permeable materials are used in chemical engineering as adsorbents, HPLC packings, membranes, catalysts, building materials or supports for biomass growth and cell culture. Here we mean by "large-pores" those above 1000 À. A review of materials and processes used in separation engineering applications is shown in Table 1. Examples in this table include polystyrene materials for HPLC like PL4000 with pore diameter of 4000 À or POROS with pores of 7000 À in diameter, BM329 (Rhone-Poulenc catalyst) with pores of 10000 Â or VERAX VX-100 beads with pores in the range of 20-40 μπι.The objectives of this review paper are: i) to provide an historical retrospective of research work on intraparticle forced convection stressing important and often forgotten contributions;ii) to discuss the concept of "augmented" diffusivity by convection and show how it explains the improved performance of separation processes;iii) to stress that an extended Van Deemter equation is needed when calculating the performance (HETP) of chromatographic processes using large-pore materials;

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Section: Performance Of Chromatographic Processes Using Permeable Parsupporting

confidence: 77%

Intraparticle Convection in Chromatographic Permeable Packings

Rodrigues

1996

ACS Symposium Series

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“…First, the dead volume, V d , of the column was obtained from the product of the dead time, t d , of the HPLC instrument and the volumetric flow rate, Q (V d = Qt d ); the dead time, t d , of the column was taken to be the measured retention time of the dead-time marker in the system without a column. Next, the average retention times, t R;i (i = 0, 1, 2, …, N), for the dead-time marker (i = 0) and the N polystyrene standards (i = 1, 2, …, N) were obtained from the average of the first moments [26] of the chromatograms from the three repeated measurements for each molecule. The elution volume, V E,i , of molecule i (i = 0, 1, 2, …, N), was simply evaluated as the product of the average retention time, t R;i (i = 0, 1, 2, …, N) and the volumetric flow rate,…”

Section: Nitrogen Adsorption Measurementsmentioning

confidence: 99%

“…Due to the fact that the elution volumes used in Eq. (1) are obtained from the first moment, l 1 , of the individual chromatograms of the standards [26], it follows that the partition coefficient could be modeled in terms of the first moments, l 1,i (i = 0, 1, 2, …, N), of the column response to a pulse injection. For a given molecule i, Eq.…”

Section: Isecmentioning

confidence: 99%

Pore structural characteristics, size exclusion properties and column performance of two mesoporous amorphous silicas and their pseudomorphically transformed MCM‐41 type derivatives

Bayram-Hahn¹,

Grimes

Lind

et al. 2007

J of Separation Science

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Highly ordered mesoporous silicas such as, mobile composition of matter, MCM-41, MCM-48, and the SBA-types of materials have helped to a large extent to understand the formation mechanisms of the pore structure of adsorbents and to improve the methods of pore structural characterization. It still remains an open question whether the high order, the regularity of the pore system, and the narrow pore size distribution of the materials will lead to a substantial benefit when these materials are employed in liquid phase separation processes. MCM-41 type 10 microm beads are synthesized following the route of pseudomorphic transformation of highly porous amorphous silicas. Highly porous silicas and the pseudomorphically transformed derivatives are characterized by nitrogen sorption at 77 K and by inverse size-exclusion chromatography (ISEC) employing polystyrene standards. Applying the network model developed by Grimes, we calculated the pore connectivity n(T) of the materials. The value of n(T) varies between the percolation threshold of the lattice and values of n(T) > 10, the latter being the limiting value above which the material can be considered to be almost infinitely connected such that the ISEC behavior of the material calculated with the pore network model is the same when calculated with a parallel pore model which assumes an infinite connectivity. One should expect that the pore connectivity is reflected in the column performance, when these native and unmodified materials are packed into columns and tested with low molecular weight analytes in the Normal Phase LC mode. As found in a previous study on monolithic silicas and highly porous silicas, the slope of the plate height (HETP) - linear velocity (u) curve decreased significantly with enhanced pore connectivity of the materials. First results on the pseudomorphically transformed MCM-41 type silicas and their highly porous amorphous precursors showed that (i) the transformation did not change the pore connectivity (within the limits detectable by ISEC) from the starting material to the final product and (ii) the slope of the HETP versus u curve for dibutylphtalate did not change significantly after the pseudomorphic transformation.

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“…[32] Theoretically it is expected that column broadening is molar mass dependent. [33] Column broadening is supposed to be consisting of several contributions including the diffusion coefficients of the polymer sample which obviously depends on the polymer molar mass. [34] The extend of column broadening and sometimes even the direction of the molar mass dependency of column broadening depends on many factors like flow rate, column quality, extracolumn broadening, contribution of adsorption effects etc.…”

mentioning

confidence: 99%

Modeling of Emulsion Polymerization, Will It Ever be Possible ? Part‐2: Determination of Basic Kinetic Data Over the Last Ten Years

Herk¹

2009

Macromolecular Symposia

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Summary: Modeling of Emulsion polymerization processes is based on the knowledge of fundamental kinetic and thermodynamic parameters. The most important kinetic parameters are propagation and termination rate coefficients. Ten years ago a paper has been published with the title ''Modeling of Emulsion Polymerization, will it ever be possible?''. The paper expresses serious doubts whether the different kinetic parameters will ever be available for general industrial recipes containing several monomers. In this paper the developments in the last 10 years regarding pulsed initiation polymerization (PIP) and other techniques regarding the determination of especially the kinetic parameters will be discussed. Amongst the areas where progress can be seen is the understanding of acrylate systems and water soluble monomers. New techniques like MALDI-ToF MS and time resolved electron spin resonance have strongly contributed to the area. Also the puzzling effect of chain length dependent propagation is discussed. Finally an answer will be given to the title question.

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Mass transfer phenomena in gel permeation chromatography

Cited by 65 publications

References 33 publications

Intraparticle Convection in Chromatographic Permeable Packings

Intraparticle Convection in Chromatographic Permeable Packings

Pore structural characteristics, size exclusion properties and column performance of two mesoporous amorphous silicas and their pseudomorphically transformed MCM‐41 type derivatives

Modeling of Emulsion Polymerization, Will It Ever be Possible ? Part‐2: Determination of Basic Kinetic Data Over the Last Ten Years

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