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Investigation of plateau methods for adsorption isotherm determination in supercritical fluid chromatography
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0003-1819-1709
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
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2014 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1354, 129-138 p.Article in journal (Refereed) Published
Abstract [en]

The Perturbation Peak (PP) method and Frontal analysis (FA) are considered as the most accurate methods for adsorption isotherms determination in liquid chromatography. In this study we investigate and explain why this is not the case in Supercritical Fluid Chromatography (SFC), where the PP method does not work at all, using a modern analytical system. The main reason was found to be that the solute to be studied must be dissolved in the MeOH reservoir before it is mixed with CO2. Since the solute occupies a certain partial volume in the reservoir, the larger the solute content the larger this fractional volume will be, and the final MeOH fraction in the mobile phase will then be smaller compared to the bulk mobile phase without solute in the modifier. If the retention of small injections on the concentration plateaus, i.e., “analytical-size” perturbation peaks, is sensitive to small variations of MeOH in the eluent, this will seriously decrease the accuracy of the PP method. This effect was verified and compensated for and we also demonstrated that the same problem will occur in frontal analysis, another concentration plateau method.

Place, publisher, year, edition, pages
2014. Vol. 1354, 129-138 p.
Keyword [en]
Adsorption isotherms, Antipyrine, Elution by Characteristic Points, Perturbation Peak method, Supercritical fluid chromatography
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kau:diva-34392DOI: 10.1016/j.chroma.2014.05.070ISI: 000339144000015PubMedID: 24931444OAI: oai:DiVA.org:kau-34392DiVA: diva2:755890
Available from: 2014-10-15 Created: 2014-10-15 Last updated: 2015-09-25Bibliographically approved
In thesis
1. Fundamental Investigations of Supercritical Fluid Chromatography
Open this publication in new window or tab >>Fundamental Investigations of Supercritical Fluid Chromatography
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis aims at a deeper understanding of Supercritical Fluid

Chromatography (SFC). Although preparative SFC has started to replace Liquid Chromatography (LC) in the pharmaceutical industry - because of its advantages in speed and its less environmental impact - fundamental understanding is still lacking. Therefore there is no rigid framework to characterize adsorption or to understand the impact of changes in operational conditions.

 

In Paper I we demonstrated, after careful system verification, that most methods applied to determine adsorption isotherms in LC could not be applied directly in SFC. This was mainly due to operational differences and to the fact that the fluid is compressible which means that everything considered constant in LC varies in SFC.

 

In Paper II we showed that the most accurate methods for adsorption isotherm determination in LC, the so called plateau methods, do not work properly for SFC. Instead, methods based on overloaded profiles should be preferred.

 

In Paper III a Design of Experiments approach was successfully used to quantitatively describe the retention behavior of several solutes and the productivity of a two component separation system. This approach can be used to optimize SFC separations or to provide information about the separation system.

 

In Paper IV severe peak distortion effects, suspected to arise from injection solvent and mobile phase fluid mismatches, were carefully investigated using experiments and simulations. By this approach it was possible to examine the underlying reasons for the distortions, which is vital for method development.

 

Finally, in Paper V, the acquired knowledge from Paper I-IV was used to perform reliable scale-up in an industrial setting for the first time. This was done by carefully matching the conditions inside the analytical and preparative column with each other. The results could therefore provide the industry with key knowledge for further implementation of SFC.

Abstract [en]

This thesis aims at a deeper understanding of Supercritical Fluid

Chromatography (SFC). Although preparative SFC has started to replace Liquid Chromatography (LC) in the pharmaceutical industry - because of its advantages in speed and its less environmental impact - fundamental understanding is still lacking. Therefore there is no rigid framework to characterize adsorption or to understand the impact of changes in operational conditions.

 

In Paper I-II it was demonstrated why most methods applied to determine adsorption isotherms in LC could not be applied directly for SFC. Methods based on extracting data from overloaded profiles should be preferred.

 

In Paper III a Design of Experiments approach was successfully used to quantitatively describe the behavior of several solutes in a

separation system. This approach can be used to optimize SFC separations or to provide information about the separation system.

 

In Paper IV severe peak distortion effects often observed in SFC were carefully investigated and explained using experiments and simulations.

 

Finally, in Paper V, the prerequisites for performing reliable and predictable scale-up of SFC were investigated by small and large scale experiments.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2015. 63 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2015:45
Keyword
Supercritical Fluid Chromatography, SFC, Modeling, Adsorption Isotherms, Scale-up, Peak Distortion, Injection, Design of Experiments, Perturbation Peak Method, Elution by Characteristic Points Method, Method transfer
National Category
Analytical Chemistry Chemical Engineering
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-37913 (URN)978-91-7063-663-9 (ISBN)
Public defence
2015-10-16, Nyquistsalen 9C 203, Karlstads universitet, Karlstad, 10:15 (English)
Opponent
Supervisors
Note

Paper 4 ("Evaluation of scale-up from analytical to preparative...") ingick som manuskript med samma titel i avhandlingen. Nu publicerad. 

Available from: 2015-09-25 Created: 2015-09-11 Last updated: 2016-03-08Bibliographically approved

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Enmark, MartinSamuelsson, JörgenForss, ErikForssén, PatrikFornstedt, Torgny
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