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Expanding the elution by characteristic point method for determination of various types of adsorption isotherms
Department of Chemistry and Biomedical Sciences, Karlstad University, Sweden.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
2011 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 24, 3737-3742 p.Article in journal (Refereed) Published
Abstract [en]

Important improvements have recently been made on the elution by characteristic point (ECP) method to increase the accuracy of the determined adsorption isotherms. However, the method has so far been limited/used for only type I adsorption isotherms (e.g. Langmuir, Toth, bi-Langmuir). In this study, general strategies are developed to expand the ECP method for the determination of more complex adsorption isotherms including such containing inflection points. We will exemplify the methodology with type II, type III and type V isotherms. Guidelines are given for how to determine such isotherms using the ECP method and for the experimental considerations that must be taken into account or that may be eliminated in the particular case.

Place, publisher, year, edition, pages
2011. Vol. 1218, no 24, 3737-3742 p.
Keyword [en]
Elution by characteristic points, Adsorption isotherms, Inflection points, Frontal analysis by characteristic points, Moreau isotherm, BET-isotherms
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-155586DOI: 10.1016/j.chroma.2011.04.035ISI: 000291576400002OAI: oai:DiVA.org:uu-155586DiVA: diva2:427418
Available from: 2011-06-28 Created: 2011-06-27 Last updated: 2017-12-11Bibliographically approved
In thesis
1. Development and improvement of methods for characterization of HPLC stationary phases
Open this publication in new window or tab >>Development and improvement of methods for characterization of HPLC stationary phases
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

High Performance Liquid Chromatography (HPLC) is a widely used tech-nique both for detecting and purifying substances in academy and in the industry. In order to facilitate the use of, and knowledge in HPLC, character-ization of stationary phases is of utmost importance. Tailor made characteri-zation methods and workflows are steadily increasing the speed and accura-cy in which new separation systems and methods are developed. In the field fundamental separation science and of preparative chromatography there is always the need for faster and more accurate methods of adsorption isotherm determination. Some of that demand are met with the steadily increase of computational power, but the practical aspects on models and methods must also be further developed. These nonlinear characterization methods will not only give models capable of describing the adsorption isotherm but also actual values of local adsorption energies and monolayer saturation capacity of an individual interaction sites etc.The studies presented in this thesis use modern alkali stable stationary phas-es as a model phase, which will give an insight in hybrid materials and their separation mechanism. This thesis will include an update and expansion in using the Elution by Characteristic Points (ECP) method for determination of adsorption isotherms. The precision is even further increased due to the ability to use slope data as well as an increase in usability by assigning a set of guidance rules to be applied when determine adsorption isotherms having inflection points. This thesis will further provide the reader with information about stationary phase characterization and the power of using existing tech-niques; combine them with each other, and also what the expansion of meth-ods can revile in terms of precision and increased usability. A more holistic view of what benefits that comes with combining a non-linear characteriza-tion of a stationary phase with more common linear characterization meth-ods are presented.

Place, publisher, year, edition, pages
Uppsala universitet, 2011. 40 p.
Keyword
Adsorption isotherms, Elution by characteristic points, Inflection points, Single component adsorption, Elution by characteristic points method, Slope data, ECP-slope method, Adsorption, Adsorption energy distribution, Adsorption isotherms, AED, Characterization of adsorption processes, Chromatographic analysis, Chromatography, Hydrophobic-subtraction method (HSM), Hydrophobicity, Linear methods, Linear Models, Liquid chromatography, metoprolol, Non-linear methods, Nonlinear methods, phenol, priority journal, propranolol, Retention mechanism, reversed phase liquid chromatography, Solvation, Subtraction method, Thermodynamics
National Category
Analytical Chemistry Biochemistry and Molecular Biology
Research subject
Chemistry with specialization in Surface Biotechnology
Identifiers
urn:nbn:se:uu:diva-166978 (URN)
Presentation
2011-10-21, C4:305, Husarg. 3, Uppsala, 10:27 (English)
Opponent
Supervisors
Available from: 2012-01-18 Created: 2012-01-18 Last updated: 2012-01-18Bibliographically approved
2. Characterization of Molecular Adsorption Using Liquid Chromatography and Mass Spectrometry
Open this publication in new window or tab >>Characterization of Molecular Adsorption Using Liquid Chromatography and Mass Spectrometry
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Molecular adsorption is a key feature in several disciplines of chemistry, covering as diverse fields as chromatographic separation to biomaterial development. This thesis aims at developing methods and techniques for the characterization of molecular adsorption at the liquid-solid interface. Two different experimental models were used, small molecular interaction characterization using liquid chromatography and complex protein adsorption on polymeric materials possible for biological sampling. Holistic approaches, where both detailed molecular interactions and identifications of trends, could improve the fundamental understanding of adsorption systems, were invariably part of the scientific process.

The characterization of small molecular interactions on liquid chromatography stationary phases via adsorption isotherm determination used combined data from physical phase parameters i.e. carbon loading, linear-, and nonlinear-characterization methods. These experiments were conducted on high performance liquid chromatography systems, using both ordinary reversed phase stationary phases, and hybrid phases. The expansion of the improved elusion by characteristic point (ECP) for adsorption isotherm determination, led to that previous impossible isotherm types, having inflexion points, now could be determined by the method. It also reduced errors in isotherm parameters due to the elimination of inaccurate determined retention times where the mobile phase concentration was zero.

The characterization of protein adsorption where performed in an unbiased way. Adsorbed proteins on different surfaces were identified using mass spectrometry (MS) and data dependent acquisition or a targeted method. Prior MS, an improved on surface enzymatic digestion (oSED) method was used to enable identification and quantitation of adsorbed protein originating from ventricular cerebrospinal fluid (vCSF). oSED was found to be able to experimentally determine large variations in protein adsorption characteristics between native and coated polycarbonate surfaces in contact with vCSF. The method was also confirmed being mechanistic in favor of enzymatic digestion of the proteins adsorbed on a surface, rather than a prior desorption into solution before digestion.

An improvement of the overall understanding of adsorption systems was not only achieved with the oSED method as a promising tool for characterization of protein adsorption on arbitrary surfaces, but also the use of linear and nonlinear approaches in stationary phase characterization that strengthened drawn conclusions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 50 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1248
National Category
Analytical Chemistry
Research subject
Chemistry with specialization in Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-249003 (URN)978-91-554-9235-9 (ISBN)
Public defence
2015-05-22, A1:111a, Husargatan 3, BMC, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2015-04-27 Created: 2015-04-09 Last updated: 2015-07-07

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