Theoretical models for peak migration in gel permeation chromatography

Casassa, Edward F.

doi:10.1021/j100695a003

Cited by 103 publications

(47 citation statements)

References 14 publications

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“…m --me +mp (15) Eqs (14) (15) illustrate that the size selectivity in SEC originates from both the average number of performed pore visits (me parameter) and the average time spent inside the pores by the macromolecule (rap parameter). The stochastic theory is able to fully characterize the SEC process since the peak profile as a function of elution time can be obtained by either analytical or numerical inversion of the CF [1, 23 27].…”

Section: Monopore Generai Modelmentioning

confidence: 99%

Experimental validation of the stochastic theory of size-exclusion chromatography: Retention on single and coupled columns

et al. 2003

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The experimental validation of the recently developed stochastic model of size-exclusion chromatography (SEC), interpreted as a random process in which macromolecules undergo a continuous exchange process between the moving zone between the packing particles and the stagnant zone inside the particles, is attempted on the basis of an extended data set of experimental chromatograms of polystyrene standards, with molar masses ranging from 0.16 to 2200 kDa, on five different columns with widely different pore sizes. Several features of experimental chromatograms of standards eluting within or outside the permeation range, such as band broadening, peak tailing and peak splitting are qualitatively interpreted at the light of the stochastic theory of SEC. Furthermore, some aspects such as the influence of sample polydispersity on peak broadeningand of the exclusion effect in the movingzone (hydrodynamic chromatographic effect) on retention are discussed.\ud A new chemometric procedure was developed for estimatingthe KSEC equilibrium distribution constant without a priori assumptions regarding the extraparticle column volume, V0 , and the total pore volume Vp . This procedure allowed to obtain an unified description of the large retention data set over different columns. All retention data belonging to calibration ranges of the various columns, followed quite similar calibration plots, under the form of KSEC = (1 – r)m, where r is the ratio of macromolecule size to pore size, with m values close to 3 for all columns. A similar approach was able to represent the behaviour of two connected column in series, with consistent values of the pertinent parameters, which validates the stochastic theory of SEC with two pore types of different sizes. Finally, this two-pore model and a mixed SEC-hydrodynamic chromatography model were compared to interpret retention data on single columns around the exclusion limits. The practical application of these approaches in routine analysis, e.g. for monitoring the column degradation during its use, is mentioned

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Section: Monopore Generai Modelmentioning

confidence: 99%

Experimental validation of the stochastic theory of size-exclusion chromatography: Retention on single and coupled columns

et al. 2003

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“…[2,3]). The widely accepted entropic approach was for the first time presented in the pioneering works of Cassassa [4,5]. However, the quantitative description of polymer retention in SEC was not yet succeeded.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and enthalpic partition retention mechanisms in liquid chromatography of non-charged synthetic polymers

Berek

2003

Chromatographia

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SummaryAdsorption and enthalpic partition processes in high performance liquid chromatography (HPLC) of macromolecules are qualitatively described and compared. These k, vo similar but not identical HPLC retention mechanisms result from enthalpic interactions bek, veen polymer sample and column packing, which are in different ways affected by interactions bek, veen eluent and column packing, and bek, veen eluent and sample. The understanding of basic principles of adsorption and enthalpic partition retention mechanisms in polymer HPLC may facilitate the suppression of their unwanted effects, as well as their appropriate coupling with the exclusion retention mechanism. The goal is an easy selection of suitable column packing, mobile phase, and temperature of system to attain desired separation and molecular characterization of particular complex polymer sample. The tailored coupling of enthalpic and entropic retention mechanisms with exclusion allows to either reduce or enhance separation selectivity of polymer species according to their molar masses. In the former case, macromolecules can be separated (practically) irrespectively of their molar mass in terms of other molecular characteristics, namely their chemical structure or physical architecture. On the contrary, increased selectivity of separation in terms of sample molar mass enables improving both the accuracy and speed of analysis. "Flower-like" enthalpic interactions of macromolecules in narrow pores may substantially affect the sample retention.

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“…The total standard free energy change then is !J.G 0 = !J.G 0 + !J.GP Therefore, equations (1) - (3) give Steric exclusion (3) ( 4) For an inert pore surface, the value of !J.GP will be zero. Statistical mechanical treatments of the steric exclusion mechanism at equil~brium calculate the loss in conformational entropy when a polymer molecule transfers from the mobile phase to a pore within the packing (1,(4)(5)(6). The distribution coefficient ~ is defined as the ratio of accessible conformations for polymer within the porous packing to those in the mobile phase.…”

Section: Thermodyeamic Interpretationmentioning

confidence: 99%

“…The theories are conveniently classified under two headings -equilibrium models and flow models. Whilst flow mechanisms are important in some experiments, there is abundant evidence indicating that most practical GPC Separationsare performed close to equilibrium conditions (1,2). The first theories of steric exclusion considered simple geometrical models from which the fraction of pore volume accessible to a solute of given size may be calculated (3).…”

Section: Introductionmentioning

confidence: 99%

“…This steric exclusion model is equivalent to the statistical mechanical treatment of the loss in conformational entropy when a macromolecule approaches an inert surface. These thermodynamic theories (1,(4)(5)(6) calculate the accessible pore volume in terms of pore size for various models of pore shape and in terms of solute size for both rigid and random coil polymers.…”

Section: Introductionmentioning

confidence: 99%

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Theory of gel permeation chromatography. Mechanism of separation and the influence of polymer-sorbent interaction

Dawkins¹

1979

Pure and Applied Chemistry

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-The displacement of hydrodynamic volume universal calibration curves to high retention volumes for some polymer-solvent systems in gel permeation chromatography is explained in terms of a network-limited separation consisting of a steric exclusion mechanism and a second mechanism resulting from polymer-sorbent interaction. This treatment is consistent with a thermodynamic interpretation of gel permeation chromatography in which the distribution coefficient (~ 1.0) for polymer-sorbent interaction is determined by an enthalpy change for polymer partition or polymer adsorption in the porous packing. Experimental data obtained with crosslinked polystyrene gels and inorganic packings may be represented by the network-limited treatment. Separations in which the distribution coefficient for polymer-sorbent interaction is less than unity correspond to partial exclusion by polymer incompatibility with the sorbent.

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Theoretical models for peak migration in gel permeation chromatography

Cited by 103 publications

References 14 publications

Experimental validation of the stochastic theory of size-exclusion chromatography: Retention on single and coupled columns

Experimental validation of the stochastic theory of size-exclusion chromatography: Retention on single and coupled columns

Adsorption and enthalpic partition retention mechanisms in liquid chromatography of non-charged synthetic polymers

Theory of gel permeation chromatography. Mechanism of separation and the influence of polymer-sorbent interaction

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