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A fundamental study of the impact of pressure on the adsorption mechanism in reversed-phase liquid chromatography
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0001-8561-6872
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. (INTERACT)ORCID iD: 0000-0003-1819-1709
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences. (Interact)ORCID iD: 0000-0002-7123-2066
2016 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1457, p. 97-106Article in journal (Refereed) Published
Resource type
Text
Abstract [en]

A fundamental investigation of the pressure effect on individual adsorption sites was undertaken based on adsorption energy distribution and adsorption isotherm measurements. For this purpose, we measured adsorption equilibrium data at pressures ranging from 100 to 1000 bar at constant flow and over a wide concentration range for three low-molecular-weight solutes, antipyrine, sodium 2-naphthalenesulfonate, and benzyltriethylammonium chloride, on an Eternity C18 stationary phase. The adsorption energy distribution was bimodal for all solutes, remaining clearly so at all pressures. The bi-Langmuir model best described the adsorption in these systems and two types of adsorption sites were identified, one with a low and another with a high energy of interaction. Evidence exists that the low-energy interactions occur at the interface between the mobile and stationary phases and that the high-energy interactions occur nearer the silica surface, deeper in the C18 layer. The contribution of each type of adsorption site to the retention factor was calculated and the change in solute molar volume from the mobile to stationary phase during the adsorption process was estimated for each type of site. The change in solute molar volume was 2-4 times larger at the high-energy site, likely because of the greater loss of solute solvation layer when penetrating deeper into the C18 layer. The association equilibrium constant increased with increasing pressure while the saturation capacity of the low-energy site remained almost unchanged. The observed increase in saturation capacity for the high-energy site did not affect the column loading capacity, which was almost identical at 50- and 950-bar pressure drops over the column. (C) 2016 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
2016. Vol. 1457, p. 97-106
Keyword [en]
UHPLC, Pressure, Adsorption isotherm, Retention factor, Loading capacity
National Category
Chemical Sciences
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kau:diva-44663DOI: 10.1016/j.chroma.2016.06.036ISI: 000380080000012PubMedID: 27357740OAI: oai:DiVA.org:kau-44663DiVA, id: diva2:952196
Available from: 2016-08-12 Created: 2016-08-12 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Fundamental and Regulatory Aspects of UHPLC in Pharmaceutical Analysis
Open this publication in new window or tab >>Fundamental and Regulatory Aspects of UHPLC in Pharmaceutical Analysis
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Ultra-high performance liquid chromatography (UHPLC) provides a considerable increase in throughput compared to HPLC and a reduced solvent consumption. The implementation of UHPLC in pharmaceutical analysis, e.g. quality control, has accelerated in recent years and there is currently a mix of HPLC and UHPLC instrumentation within pharmaceutical companies. There are, however, technical and regulatory challenges converting a HPLC method to UHPLC making it difficult to take full advantage of UHPLC in regulatory-focused applications like quality control in pharmaceutical production.

Using chromatographic modelling and fundamental theory, this thesis investigated method conversion between HPLC and UHPLC. It reports on the influence of temperature gradients due to viscous heating, pressure effects and stationary phase properties on the separation performance. It also presents a regulatory concept for less regulatory interaction for minor changes to approved methods to support efficient life cycle management.

The higher pressure in UHPLC gave a retention increase of up to 40% as compared to conventional HPLC while viscous heating, instead, reduced retention and the net result was very solute dependent. Selectivity shifts were observed even between solutes with similar structure when switching between HPLC and UHPLC and an experimental method to predict such selectivity shifts was therefore developed. The peak shape was negatively affected by the increase in pressure for some solutes since secondary interactions between the solute and the stationary phase increased with pressure.

With the upcoming ICH Q12 guideline, it will be possible for the industry to convert existing methods to UHPLC in a more flexible way using the deeper understanding and the regulatory concept presented here as a case example.

Abstract [en]

Ultra-high performance liquid chromatography (UHPLC) provides a considerable increase in throughput compared to conventional HPLC and a reduced solvent consumption. The implementation of UHPLC in pharmaceutical analysis has accelerated in recent years and currently both instruments are used. There are, however, technical and regulatory challenges converting a HPLC method to UHPLC making it difficult to take full advantage of UHPLC in regulatory-focused applications like quality control in pharmaceutical production. In UHPLC, the column is packed with smaller particles than in HPLC resulting in higher pressure and viscous heating. Both the higher pressure and the higher temperature may cause changes in retention and selectivity making method conversion unpredictable.

Using chromatographic modelling and fundamental theory, this thesis investigates method conversion between HPLC and UHPLC. It reports on the influence of temperature gradients due to viscous heating, pressure effects and stationary phase properties on the separation performance. It also presents a regulatory concept for less regulatory interaction for minor changes to approved quality control methods and how predicable method conversion is achieved by improved understanding.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2017. p. 75
Series
Karlstad University Studies, ISSN 1403-8099 ; 2017:9
Keyword
Liquid chromatography, UHPLC, Pharmaceutical analysis, Adsorption isotherm, Design of experiments, Quality control
National Category
Analytical Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kau:diva-47852 (URN)978-91-7063-756-8 (ISBN)978-91-7063-757-5 (ISBN)
Public defence
2017-04-06, 9C204, Rejmersalen, Karlstads universitet, Universitetsgatan 2, Karlstad, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 2015-04627ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 15/497
Available from: 2017-03-08 Created: 2017-02-10 Last updated: 2017-07-26Bibliographically approved

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Åsberg, DennisSamuelsson, JörgenFornstedt, Torgny

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