Theory of concentration effects in gel permeation chromatography

Janča, Josef

doi:10.1021/ac50042a011

Cited by 37 publications

(9 citation statements)

References 34 publications

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“…Thus, the elution rate of the large macromolecules is further accelerated. The term secondary exclusion was coined by Altgelt 88 and the theory of the process was elaborated by Janča 89. The concentration effects. This term describes variations in V R of the polymer samples due to changes of injected concentration, c i .…”

Section: Problems Of Secmentioning

confidence: 99%

“…Thus, the elution rate of the large macromolecules is further accelerated. The term secondary exclusion was coined by Altgelt 88 and the theory of the process was elaborated by Janča 89.…”

Section: Problems Of Secmentioning

confidence: 99%

“…The concentration dependences of V R in SEC are likely affected also by the viscosity effects and by the secondary exclusion 89.…”

Section: Problems Of Secmentioning

confidence: 99%

See 2 more Smart Citations

Size exclusion chromatography – A blessing and a curse of science and technology of synthetic polymers

Berek

2010

J of Separation Science

154

126

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Size exclusion chromatography, SEC is one of the most popular methods for the separation of different kinds of macromolecules. This critical review gives concise information about macromolecules and their behavior in solution, basic understanding about principles, instrumentation, and application possibilities of SEC, and more in detail discusses drawbacks and pitfalls of the method with the emphasis on synthetic polymers. Selected practical advices are included to help enhance the quality of SEC results.

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Section: Problems Of Secmentioning

confidence: 99%

“…Thus, the elution rate of the large macromolecules is further accelerated. The term secondary exclusion was coined by Altgelt 88 and the theory of the process was elaborated by Janča 89.…”

Section: Problems Of Secmentioning

confidence: 99%

See 1 more Smart Citation

Size exclusion chromatography – A blessing and a curse of science and technology of synthetic polymers

Berek

2010

J of Separation Science

154

126

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“…Even in cases where the typical waves on the rear of peaks are not clearly visible, the phenomenon of viscous fingering can thus lead to increased band broadening, accompanied by a shift towards higher retention times. A quantitative theoretical treatment of viscosity effects has been given by Janca [10]. In order to distinguish experimentally the effects of coil contraction and viscosity, different strategies have been tried: the size effect should be nonexistent in theta solvents [11] or for totally excluded polymer samples [12], and viscosity effects can be avoided in static experiments [13].…”

Section: Introductionmentioning

confidence: 99%

Viscous fingering: a systematic study of viscosity effects in methanol-isopropanol systems

et al. 1997

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SummaryUpon injection of concentrated polymer solutions in size exclusion chromatography, a random peak deformation has been observed and attributed to viscous fingering. In order to characterize this phenomenon, which is due to the difference in sample and eluent viscosities, mixtures of methanol and isopropanol are used as a low-molecular weight model. This system permits the study of viscosity effects in the absence of any adsorption or exclusion. Depending on the percentage of isopropanol added to a pure methanol mobile phase or to a methanol "sample" plug, a wide range of sample and eluent viscosities can be obtained. Statistical moments are used to compare elution profiles and to correlate peak deformation to viscosity differences. Significant loss of efficiency is observed whenever sample and eluent viscosity differ by more than 10 %.

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“…On the other hand, the full understanding of the origin of concentration effects is important whenever any auxiliary phenomena are studied, such as solution behavior of the UHMM polymers, the possible chain degradation, the emergence of the hydrodynamic instabilities under the conditions of Micro-TFFF, etc. Our previous experience with the effect of concentration, published in several papers concerned the separations of the polymers by SizeExclusion Chromatography (SEC) [4][5][6][7][8] and it was reproduced later by some authors in the studies of the separations in liquid chromatography. This experience inspired the idea [9] that the dominant contribution to the shift of the retention volume and perturbation of the elution profile is due to viscosity gradients and consequent hydrodynamic effects like Rayleigh-Taylor gravitational instability or Saffman-Taylor instability (viscous fingering effect).…”

Section: Introductionmentioning

confidence: 99%

On the Concentration Effects in Micro-Thermal Field-Flow Fractionation of Polymers

Janča

Ananieva

2008

Journal of Liquid Chromatography & Related Technologies

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Micro-Thermal Field-Flow Fractionation (Micro-TFFF) was used to study the effect of concentration of the polymer solutions injected into the separation channel. The range of the investigated concentrations was very large, becoming higher then the critical values at which the entanglement of the polymer coils leads to the formation of the macromolecular aggregates. The samples of different molar masses were used and the experiments were carried out at different temperature drops across the channel and at different temperatures of the cold wall. The multiple peaks (or oscillations) that appeared on the fractograms at a given concentration of the injected sample solution and at a given temperature drop, disappeared at lower concentration and emerged again at the same lower concentration, but at a higher temperature drop. Although the observed broadening of the fractograms can be partially caused by the formation of the macromolecular aggregates, their presence cannot explain the secondary peaks or oscillations appearing on the fractograms at the retentions corresponding to extremely high molar masses. The hydrodynamic and=or gravitational instabilities, which are caused by the formed viscosity and density gradients inside the separation channel are the most probable explanation of the origin of the mentioned secondary peaks and=or oscillations emerging at high concentrations and=or high temperature drops.

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Theory of concentration effects in gel permeation chromatography

Cited by 37 publications

References 34 publications

Size exclusion chromatography – A blessing and a curse of science and technology of synthetic polymers

Size exclusion chromatography – A blessing and a curse of science and technology of synthetic polymers

Viscous fingering: a systematic study of viscosity effects in methanol-isopropanol systems

On the Concentration Effects in Micro-Thermal Field-Flow Fractionation of Polymers

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