1
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Hamano Y, Inagawa A, Otsuka T, Kageyama R, Ogawa J, Roppongi M, Higashiguchi T, Uehara N. Elucidating the Quenching Mechanism of Tris(2,2'-bipyridyl)ruthenium(II) Complex in the Water-Glycerol Binary System Based on the Microscopic Structure of the Media. J Phys Chem B 2024; 128:1771-1779. [PMID: 38329904 DOI: 10.1021/acs.jpcb.3c07882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Kinetic studies on the photochemical quenching reaction of the tris(2,2'-bipyridyl) ruthenium(II) complex ([Ru(bpy)3]2+) in water-glycerol binary media were conducted based on the Einstein-Smoluchowski (E-S) theory. Dynamic and static quenching behaviors were analyzed by comparing results from time-resolved spectroscopy and emission spectroscopy. While the dynamic quenching reaction aligns well with the E-S theory, static quenching was observed, leading to a notable increase in the overall photoquenching reaction rate constant. Employing chromatography and infrared spectroscopy, we correlated the microscopic molecular structure of the binary solvent system and the solvation environment around the emitters with the reaction mechanism. This correlation was found to correspond to ion pair formation and the confinement effect of the emitter, respectively.
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Affiliation(s)
- Yuki Hamano
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
| | - Arinori Inagawa
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
| | - Takuhiro Otsuka
- Department of Chemistry, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8551,Japan
| | - Ryo Kageyama
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
| | - Juri Ogawa
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
| | - Makoto Roppongi
- Center for Instrumental Analysis, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585, Japan
| | - Takeshi Higashiguchi
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
| | - Nobuo Uehara
- Faculty of Engineering, Utsunomiya University, 7-1-2, Yoto, Utsunomiya, Tochigi 321-8585,Japan
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Niezen LE, Sasaki T, Sadriaj D, Ritchie H, Broeckhoven K, Cabooter D, Desmet G. Detailed analysis of the effective and intra-particle diffusion coefficient of proteins at elevated pressure in columns packed with wide-pore core-shell particles. J Chromatogr A 2024; 1713:464538. [PMID: 38043163 DOI: 10.1016/j.chroma.2023.464538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 11/23/2023] [Accepted: 11/26/2023] [Indexed: 12/05/2023]
Abstract
To determine the efficiency that can be obtained in a packed-bed liquid-chromatography column for a particular analyte, a correct determination of the molecular and effective diffusion coefficients (Dm and Deff) of the analyte is required. The latter is usually obtained via peak parking experiments wherein the flow is stopped. As a result, the column pressure rapidly dissipates and the measurement is essentially conducted at ambient pressure. This is problematic for analytes whose retention depends on pressure, such as proteins and potentially other large (dipolar) molecules. In that case, a conventional peak parking experiment is expected to lead to large errors in Deff. To obtain a better estimate ofDeff, the present study reports on the use of a set-up enabling peak parking measurements under pressurized conditions. This approach allowed us to report, for the first time, Deff for proteins at elevated pressure under retained conditions. First, Deff was determined at a (average) pressure of about 105 bar for a set of proteins with varying size, namely: bradykinin, insulin, lysozyme, β-lactoglobulin, and carbonic anhydrase in a column packed with 400 Å core-shell particles. The obtained data were then compared to those of several small analytes: acetophenone, propiophenone, benzophenone, valerophenone, and hexanophenone. A clear trend between Deff and analyte size was observed. The set-up was then used to determine Deff of bradykinin and lysozyme at variable (average) pressures ranging from 28 bar to 430 bar. These experiments showed a decrease in intra-particle and surface diffusion with pressure, which was larger for lysozyme than bradykinin. The data show that pressurized peak parking experiments are vital to correctly determine Deff when the analyte retention varies significantly with pressure.
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Affiliation(s)
- Leon E Niezen
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussel, Belgium
| | - Tsukasa Sasaki
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussel, Belgium
| | - Donatela Sadriaj
- University of Leuven (KU Leuven), Department for Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, Herestraat 49, Leuven, Belgium
| | - Harald Ritchie
- Advanced Materials Technology, Silverside Rd, Wilmington, DE, USA
| | - Ken Broeckhoven
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussel, Belgium
| | - Deirdre Cabooter
- University of Leuven (KU Leuven), Department for Pharmaceutical and Pharmacological Sciences, Pharmaceutical Analysis, Herestraat 49, Leuven, Belgium
| | - Gert Desmet
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussel, Belgium.
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3
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Fekete S, Lauber MA. Theoretical study on solute migration and band broadening occurring in pressure-enhanced liquid chromatography. J Chromatogr A 2023; 1692:463872. [PMID: 36804800 DOI: 10.1016/j.chroma.2023.463872] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/09/2023] [Accepted: 02/11/2023] [Indexed: 02/17/2023]
Abstract
Upon recently studying the use of pressure gradients during liquid chromatography (LC), it was noted that pressure differentials across a column can have a significant impact on peak shape, not just retention as has been noted several times before. Theoretical models and thought experiments were performed here to more carefully study these effects. Two situations have been elucidated. The first is one that reflects a protein reversed phase separation wherein solute retention increases with pressure. In this condition, it has been found that a positive pressure gradient will result in band broadening while a negative pressure gradient will help yield sharper peaks. The second case that has come to be better appreciated is when solute retention decreases with pressure, which can occur in protein ion exchange (IEX) and hydrophobic interaction chromatography (HIC). In this situation, a positive pressure gradient will conversely result in peak sharpening, and a negative pressure gradient will introduce band broadening. These observations have facilitated making new fundamental understandings on pressurized separations which has in turn made it possible to begin envisioning new ways of and reasons for applying pressure enhanced LC methods.
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Affiliation(s)
- Szabolcs Fekete
- Waters Corporation, located in CMU-Rue Michel Servet 1, 1211 Geneva 4, Switzerland.
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4
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Kristl A, Caf M, Pompe M, Podgornik A. Complex Protein Retention Shifts with a Pressure Increase: An Indication of a Standard Partial Molar Volume Increase during Adsorption? Anal Chem 2022; 94:13350-13358. [PMID: 36124423 PMCID: PMC9535627 DOI: 10.1021/acs.analchem.2c01809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Studies of protein adsorption on reversed-phase and ion
exchange
stationary phases demonstrated an increase in retention with increasing
pressure, which is interpreted as a standard partial molar volume
decrease during the transition of the protein from a mobile to a stationary
phase. Investigation of the pressure effect on the retention of lysozyme
and IgG on a cation exchange column surprisingly revealed a negative
retention trend with the increase of pressure. Further investigation
of this phenomenon was performed with β-lactoglobulin, which
enabled adsorption to be studied on both cation and anion exchange
columns using the same mobile phase with a pH of 5.2. The same surface
charge and standard partial molar volume in the mobile phase allowed
us to examine only the effect of adsorption. Interestingly, a negative
retention trend with a pressure increase occurred on an anion exchange
column while a positive trend was present on a cation exchange column.
This indicates that the interaction type governs the change in the
standard partial molar volume during adsorption, which is independent
of the applied pressure. Increasing the protein charge by decreasing
the pH of the mobile phase to 4 reversed the retention trend (into
a negative) with a pressure increase on the cation exchange column.
A further decrease of the pH value resulted in an even more pronounced
negative trend. This counterintuitive behavior indicates an increase
in the standard partial molar volume during adsorption with the protein
charge, possibly due to intermolecular repulsion of adsorbed protein
molecules. While a detailed mechanism remains to be elucidated, presented
results demonstrate the complexity of ion exchange interactions that
can be investigated simply by changing the column pressure.
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Affiliation(s)
- Anja Kristl
- Institute of Forensic Medicine, Faculty of Medicine, University of Ljubljana, Korytkova ulica 2, Ljubljana 1000, Slovenia.,Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia
| | - Maja Caf
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia
| | - Matevž Pompe
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia
| | - Aleš Podgornik
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, Ljubljana 1000, Slovenia.,COBIK, Mirce 21, Ajdovščina 5270, Slovenia
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5
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Recycling gradient-elution liquid chromatography for the analysis of chemical-composition distributions of polymers. J Chromatogr A 2022; 1679:463386. [DOI: 10.1016/j.chroma.2022.463386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/13/2022] [Accepted: 07/27/2022] [Indexed: 11/18/2022]
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6
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Fekete S, Fogwill M, Lauber MA. Pressure-Enhanced Liquid Chromatography, a Proof of Concept: Tuning Selectivity with Pressure Changes and Gradients. Anal Chem 2022; 94:7877-7884. [PMID: 35607711 PMCID: PMC9178557 DOI: 10.1021/acs.analchem.2c00464] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Many chromatographers
have observed that the operating pressure
can dramatically change the chromatographic retention of solutes.
Small molecules show observables changes, yet even more sizable effects
are encountered with large biomolecules. With this work, we have explored
the use of pressure as a method development parameter to alter the
reversed-phase selectivity of peptide and protein separations. An
apparatus for the facile manipulation of column pressure was assembled
through a two-pump system and postcolumn flow restriction. The primary
pump provided an eluent flow through the column, while the secondary
pump provided a pressure-modulating flow at a tee junction after the
column but ahead of a flow restrictor. Using this setup, we were able
to quickly program various constant pressure changes and even pressure
gradients. It was reconfirmed that pressure changes impact the retention
of large molecules to a much greater degree than small molecules,
making it especially interesting to consider the use of pressure to
selectively separate solutes of different sizes. The addition of pressure
to bring the column operating pressure beyond 500 bar was enough to
change the elution order of insulin (a peptide hormone) and cytochrome
C (a small serum protein). Moreover, with the proposed setup, it was
possible to combine eluent and pressure gradients in the same analytical
run. This advanced technique was applied to improve the separation
of insulin from one of its forced degradation impurities. We have
referred to this method as pressure-enhanced liquid chromatography
and believe that it can offer unseen selectivity, starting with peptide
and protein reversed-phase separations.
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Affiliation(s)
- Szabolcs Fekete
- Waters Corporation, CMU-Rue Michel Servet 1, 1211 Geneva 4, Switzerland
| | - Michael Fogwill
- Waters Corporation, 34 Maple Street, Milford, Massachusetts 01757, United States
| | - Matthew A Lauber
- Waters Corporation, 34 Maple Street, Milford, Massachusetts 01757, United States
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7
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Kristl A, Lukšič M, Pompe M, Podgornik A. Effect of Pressure Increase on Macromolecules' Adsorption in Ion Exchange Chromatography. Anal Chem 2020; 92:4527-4534. [PMID: 32075366 PMCID: PMC7307832 DOI: 10.1021/acs.analchem.9b05729] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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In this study a new
method for evaluating the pressure effect on
separations of oligonucleotides and proteins on an anion exchange
column was developed. The pressure rise of up to 500 bar was attained
by coupling restriction capillaries to the column outlet to minimize
differences in pressure over the column. Using pH transient measurements
it was demonstrated that no shift in ion exchange equilibria occurs
due to a pressure increase. Results from isocratic and gradient separations
of oligonucleotides (model compounds) were evaluated by stoichiometric
displacement and linear gradient elution model, respectively. Both
elution modes demonstrated that for smaller oligonucleotides the number
of binding sites remained unchanged with pressure rise while an increase
for large oligonucleotides was observed, indicating their alignment
over the stationary phase. From the obtained model parameters and
their pressure dependencies, a thermodynamic description was made
and compared between the elution modes. A complementary pattern of
a linear increase of partial molar volume change with a pressure rise
was established. Furthermore, estimation of the pressure effect was
performed for bovine serum albumin and thyroglobulin that required
gradient separations. Again, a raise in binding site number was found
with pressure increase. The partial molar volume changes of BSA and
Tg at the maximal investigated pressure and minimal salt concentration
were −31.6 and −34.4 cm3/mol, respectively,
indicating a higher rigidity of Tg. The proposed approach provides
an insight into the molecule deformation over a surface at high pressures
under nondenaturing conditions. The information enables a more comprehensive
UHPLC method development.
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Affiliation(s)
- Anja Kristl
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Miha Lukšič
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Matevž Pompe
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Aleš Podgornik
- Faculty for Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.,COBIK, Tovarniška 26, 5270 Ajdovščina, Slovenia
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8
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Prauda I, Bartó E, Felinger A. Influence of pressure on the retention of resorcinarene-based cavitands. J Chromatogr A 2018; 1535:123-128. [DOI: 10.1016/j.chroma.2018.01.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/07/2018] [Accepted: 01/08/2018] [Indexed: 10/18/2022]
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9
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Gritti F, Besner S, Cormier S, Gilar M. Applications of high-resolution recycling liquid chromatography: From small to large molecules. J Chromatogr A 2017; 1524:108-120. [DOI: 10.1016/j.chroma.2017.09.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/11/2017] [Accepted: 09/23/2017] [Indexed: 11/25/2022]
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10
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Gritti F, Leal M, McDonald T, Gilar M. Ideal versus real automated twin column recycling chromatography process. J Chromatogr A 2017; 1508:81-94. [DOI: 10.1016/j.chroma.2017.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 10/19/2022]
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11
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Schuster SA, Wagner BM, Boyes BE, Kirkland JJ. Optimized superficially porous particles for protein separations. J Chromatogr A 2013; 1315:118-26. [PMID: 24094750 PMCID: PMC8214819 DOI: 10.1016/j.chroma.2013.09.054] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/16/2013] [Accepted: 09/17/2013] [Indexed: 11/24/2022]
Abstract
Continuing interest in larger therapeutic molecules by pharmaceutical and biotech companies provides the need for improved tools for examining these molecules both during the discovery phase and later during quality control. To meet this need, larger pore superficially porous particles with appropriate surface properties (Fused-Core(®) particles) have been developed with a pore size of 400 Å, allowing large molecules (<500 kDa) unrestricted access to the bonded phase. In addition, a particle size (3.4 μm) is employed that allows high-efficiency, low-pressure separations suitable for potentially pressure-sensitive proteins. A study of the shell thickness of the new fused-core particles suggests a compromise between a short diffusion path and high efficiency versus adequate retention and mass load tolerance. In addition, superior performance for the reversed-phase separation of proteins requires that specific design properties for the bonded-phase should be incorporated. As a result, columns of the new particles with unique bonded phases show excellent stability and high compatibility with mass spectrometry-suitable mobile phases. This report includes fast separations of intact protein mixtures, as well as examples of very high-resolution separations of larger monoclonal antibody materials and associated variants. Investigations of protein recovery, sample loading and dynamic range for analysis are shown. The advantages of these new 400 Å fused-core particles, specifically designed for protein analysis, over traditional particles for protein separations are demonstrated.
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Affiliation(s)
- Stephanie A Schuster
- Advanced Materials Technology, Inc., 3521 Silverside Road, Suite 1-K, Quillen Building, Wilmington, DE 19810, USA.
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12
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Wagner BM, Schuster SA, Boyes BE, Kirkland JJ. Superficially porous silica particles with wide pores for biomacromolecular separations. J Chromatogr A 2012; 1264:22-30. [PMID: 23068761 PMCID: PMC3500911 DOI: 10.1016/j.chroma.2012.09.052] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/11/2012] [Accepted: 09/15/2012] [Indexed: 10/27/2022]
Abstract
Since 2006, columns of superficially porous particles (SPPs), often called Fused-core(®), porous-shell or core-shell particles, have had serious impact on HPLC separations. These particles have pore diameters of about 100Å designed for separating small molecules. More recently, SPPs with 160-200Å pore diameter have been made available for separating peptides and small proteins. This report describes the effects of fused-core particle size, pore size, shell thickness and ligand type for the rapid, efficient separation of larger molecules such as intact proteins and other biomacromolecules up to at least 400 kDa. Optimization of these parameters resulted in particles that show no restricted diffusion that would compromise separating efficiency for large biomolecules. The thin porous shell provides excellent mass transfer (kinetics) for these large molecules, resulting in superior separations compared to conventional totally porous particles. Sample loading capacity can be adjusted to allow good detection sensitivity for minor components in a complex mixture. Strong particle strength ensures the loading of stable, high-efficiency columns. Stationary phases with different alkyl ligands were tested to provide data on retention, column efficiency and peak shapes for proteins. The development of these new wide-pore fused-core particles now allows the HPLC separation of a wide range of molecules of different sizes with advantages of the SPP configuration.
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Affiliation(s)
- Brian M Wagner
- Advanced Materials Technology, Inc., 3521 Silverside Rd., Ste. 1-K, Quillen Bldg, Wilmington, DE 19810, USA
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13
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Evaluation of recent very efficient wide-pore stationary phases for the reversed-phase separation of proteins. J Chromatogr A 2012; 1252:90-103. [DOI: 10.1016/j.chroma.2012.06.066] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/22/2022]
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14
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Repeatability of the efficiency of columns packed with sub-3μm core–shell particles: Part II. 2.7μm Halo-ES-Peptide-C18 particles in 4.6mm and 2.1mm×100mm column formats. J Chromatogr A 2012; 1252:45-55. [DOI: 10.1016/j.chroma.2012.05.063] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 11/22/2022]
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15
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Gritti F, Guiochon G. Repeatability of the efficiency of columns packed with sub-3μm core–shell particles: Part I. 2.6μm Kinetex-C18 particles in 4.6mm and 2.1mm×100mm column formats. J Chromatogr A 2012; 1252:31-44. [DOI: 10.1016/j.chroma.2012.05.072] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 05/17/2012] [Accepted: 05/21/2012] [Indexed: 10/28/2022]
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16
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Fekete S, Veuthey JL, Guillarme D. New trends in reversed-phase liquid chromatographic separations of therapeutic peptides and proteins: theory and applications. J Pharm Biomed Anal 2012; 69:9-27. [PMID: 22475515 DOI: 10.1016/j.jpba.2012.03.024] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 12/22/2022]
Abstract
In the pharmaceutical field, there is considerable interest in the use of peptides and proteins for therapeutic purposes. There are various ways to characterize such complex samples, but during the last few years, a significant number of technological developments have been brought to the field of RPLC and RPLC-MS. Thus, the present review focuses first on the basics of RPLC for peptides and proteins, including the inherent problems, some possible solutions and some directions for developing a new RPLC method that is dedicated to biomolecules. Then the latest advances in RPLC, such as wide-pore core-shell particles, fully porous sub-2 μm particles, organic monoliths, porous layer open tubular columns and elevated temperature, are described and critically discussed in terms of both kinetic efficiency and selectivity. Numerous applications with real samples are presented that confirm the relevance of these different strategies. Finally, one of the key advantages of RPLC for peptides and proteins over other historical approaches is its inherent compatibility with MS using both MALDI and ESI sources.
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Affiliation(s)
- Szabolcs Fekete
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Bd d'Yvoy 20, 1211 Geneva 4, Switzerland.
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17
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Easy and accurate high-performance liquid chromatography retention prediction with different gradients, flow rates, and instruments by back-calculation of gradient and flow rate profiles. J Chromatogr A 2011; 1218:6742-9. [DOI: 10.1016/j.chroma.2011.07.070] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/09/2011] [Accepted: 07/21/2011] [Indexed: 11/19/2022]
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18
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Buszewski B, Bocian S, Zera R. Influence of temperature and pressure on the preferential adsorption of component of hydroorganic mobile phase in liquid chromatography. ADSORPTION 2010. [DOI: 10.1007/s10450-010-9236-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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19
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Comparison of the mass transfer in totally porous and superficially porous stationary phases in liquid chromatography. Anal Bioanal Chem 2010; 397:1307-14. [DOI: 10.1007/s00216-010-3627-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 02/24/2010] [Accepted: 02/28/2010] [Indexed: 11/26/2022]
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20
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Gritti F, Guiochon G. Fundamental chromatographic equations designed for columns packed with very fine particles and operated at very high pressures. J Chromatogr A 2008; 1206:113-22. [DOI: 10.1016/j.chroma.2008.07.084] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 07/16/2008] [Accepted: 07/25/2008] [Indexed: 10/21/2022]
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21
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Li X, Chen G, Fekete J, Yang F, Fekete A, Englmann M, Schmitt‐Kopplin P. Optimization of Gradient Elution in UPLC: A Core Study on the Separation of Homoserine Lactones Produced by Bukholderia Ubonensis and Structure Confirmation with Ultra High Resolution Mass Spectrometry. J LIQ CHROMATOGR R T 2007. [DOI: 10.1080/10826070701540084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Xiaojing Li
- a Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, and Department of Chemistry , Fuzhou University , Fuzhou, Fujian, China
| | - Guonan Chen
- a Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, and Department of Chemistry , Fuzhou University , Fuzhou, Fujian, China
| | - Jenoe Fekete
- b Faculty of Chemical Engineering, Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry , Budapest, Hungary
| | - Fang Yang
- c FJCIQ‐Fujian Entry‐Exit Inspection and Quarantine Bureau, Technical Center , Fuzhou, Fujian, China
| | - Agnes Fekete
- d GSF‐National Research Center for Environment and Health, Institute of Ecological Chemistry , Neuherberg, Germany
| | - Matthias Englmann
- d GSF‐National Research Center for Environment and Health, Institute of Ecological Chemistry , Neuherberg, Germany
| | - Philippe Schmitt‐Kopplin
- d GSF‐National Research Center for Environment and Health, Institute of Ecological Chemistry , Neuherberg, Germany
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22
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Marchetti N, Guiochon G. Separation of peptides from myoglobin enzymatic digests by RPLC. Influence of the mobile-phase composition and the pressure on the retention and separation. Anal Chem 2007; 77:3425-30. [PMID: 15924371 DOI: 10.1021/ac050541c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The influence of the mobile-phase composition and the pressure on the chromatographic separation of the peptides from the enzymatic digest of myoglobin was studied under linear conditions. The retention behavior of these tryptic peptides was measured under isocratic conditions with different mobile-phase compositions, ranging from 9 to 28% (v/v) acetonitrile in 0.1% (v/v) aqueous trifluoroacetic acid. The effect of the pressure was studied by analyzing the separation of the tryptic peptides under different average column pressures between 14 and 220 bar, at 13, 20, and 26% (v/v) acetonitrile. The differences between the partial molar volumes of these peptides in the stationary and mobile phases were derived from these results. All the measurements were performed on a 10-cm-long C18-bonded, end-capped monolithic column. The results obtained illustrate the highly complicated behavior of the complex peptide mixtures afforded by tryptic digestion. The capacity factors of the analyzed peptides do not depend linearly on the acetonitrile concentration but follow exactly a quadratic relationship. The adsorption changes of partial molar volumes are in good agreement with other literature data. The consequences of the influence of the average column pressure (hence of the flow rate) on the column phase ratio and on the retention factors of the peptides are discussed. The retention pattern of the complex mixture is affected by both the mobile-phase composition and the pressure, and the resolution of certain peptide pairs is so much affected by the pressure that inversions in the elution order of some pairs are observed.
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Affiliation(s)
- Nicola Marchetti
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996-1600, USA
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Liao Z, Orendorff CJ, Pemberton JE. Effect of Pressurized Solvent Environments on the Alkyl Chain Order of Octadecylsilane Stationary Phases by Raman Spectroscopy. Chromatographia 2006. [DOI: 10.1365/s10337-006-0005-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Ahmad T, Guiochon G. Effect of the mobile phase composition on the adsorption behavior of tryptophan in reversed-phase liquid chromatography. J Chromatogr A 2006; 1114:111-22. [PMID: 16530206 DOI: 10.1016/j.chroma.2006.02.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Revised: 02/15/2006] [Accepted: 02/17/2006] [Indexed: 11/22/2022]
Abstract
Single-component adsorption isotherm data of l-tryptophan on a C18-bonded silica column were acquired by frontal analysis (FA), with aqueous mobile phases containing 2.5, 5, and 7.5% of acetonitrile (ACN) or 7, 10, 15, and 20% of methanol (MeOH). Most of these isotherms have two inflection points and three different parts. The low and the high concentration parts exhibit langmuirian behavior. The intermediate part exhibits anti-langmuirian behavior. The inflection points shift toward higher concentrations with increasing mobile phase concentration in ACN or MeOH, which causes the differences in the isotherm profiles. The nature of the organic modifier and its concentration affect only the isotherm profile and the numerical values of its parameters, not the nature of the best model, which is the bi-Moreau model in all cases. The isotherm profiles depend on the experimental conditions because they affect the intensity of the adsorbate-adsorbate interactions. Overloaded band profiles of tryptophan were recorded with the seven mobile phase compositions. They were used to determine the best values of the isotherm coefficients by the inverse method (IM) of chromatography. There is an excellent agreement between the values of these parameters obtained by FA and by IM. Increasing the concentration of either ACN or MeOH in the mobile phase causes a slight decrease in the saturation capacities of the low and the high energy sites, and in the adsorption constant of the low energy sites. The adsorption constant of the high energy sites increases with increasing concentration of either solvent or is little affected. The adsorbate-adsorbate interaction constants of both low and high energy sites increase for both solvents. Saturation capacities of the high energy sites are higher for ACN than for MeOH.
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Affiliation(s)
- Tarab Ahmad
- Department of Chemistry, University of Tennessee, 552 Buehler Hall, Knoxville, TN 37996-1600, USA
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Gritti F, Guiochon G. Critical contribution of nonlinear chromatography to the understanding of retention mechanism in reversed-phase liquid chromatography. J Chromatogr A 2005; 1099:1-42. [PMID: 16271269 DOI: 10.1016/j.chroma.2005.09.082] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 09/23/2005] [Accepted: 09/27/2005] [Indexed: 11/25/2022]
Abstract
The retention of most compounds in RPLC proceeds through a combination of several independent mechanisms. We review a series of recent studies made on the behavior of several commercial C18-bonded stationary phases and of the complex, mixed retention mechanisms that were observed in RPLC. These studies are essentially based on the acquisition of adsorption isotherm data, on the modeling, and on the interpretation of these data. Because linear chromatography deals only with the initial slope of the global, overall, or apparent isotherm, it is unable fully to describe the complete adsorption mechanism. It cannot even afford clues as to the existence of several overlaid retention mechanisms. More specifically, it cannot account for the consequences of the surface heterogeneity of the packing material. The acquisition of equilibrium data in a wide concentration range is required for this purpose. Frontal analysis (FA) of selected probes gives data that can be modeled into equilibrium isotherms of these probes and that can also be used to calculate their adsorption or affinity energy distribution (AED). The combination of these data, the detailed study of the best constants of the isotherm model, the determination of the influence of experimental parameters (e.g., buffer pH and pI, temperature) on the isotherm constants provide important clues regarding the heterogeneity of the adsorbent surface and the main properties of the adsorption mechanisms. The comparison of similar data obtained for the adsorption of neutral and ionizable compounds, treated with the same approach, and the investigation of the influence on the thermodynamics of phase equilibrium of the experimental conditions (temperature, average pressure, mobile phase composition, nature of the organic modifier, and, for ionizable compounds, of the ionic strength, the nature, the concentration of the buffer, and its pH) brings further information. This review provides original conclusions regarding retention mechanisms in RPLC.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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Abstract
All the experimental parameters that the chromatographers are used to consider as constant (the column length and its diameter, the particle size, the column porosities, the phase ratio, the column hold-up volume, the pressure gradient along the column, the mobile phase density and its viscosity, the diffusion coefficients, the equilibrium constants, the retention factors, the efficiency parameters) depend on pressure to some extent. While this dependence is negligible as long as experiments, measurements, and separations are carried out under conventional pressures not exceeding a few tens of megapascal, it is no longer so when the inlet pressure becomes much larger and exceeds 100 MPa. Equations are developed to determine the extent of the influence of pressure on all these parameters and to account for it. The results obtained are illustrated with graphics. The essential results are that (1) many parameters depend on the inlet pressure, hence on the flow rate; (2) the apparent reproducibility of parameters as simple as the retention factor will be poor if measurements are carried out at different flow rates, unless due corrections are applied to the results; (3) the influence of the temperature on the equilibrium constants should be studied under constant inlet pressure rather than at a constant flow rate, to minimize the coupling effect of pressure and temperature through the temperature dependence of the viscosity; and (4) while reproducibility of results obtained at constant pressure and flow rate will not be affected, method development becomes far more complex because of the pressure dependence of everything.
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Affiliation(s)
- Michel Martin
- Laboratoire de Physique et Mécanique des Milieux Héérogènes, Ecole Supérieure de Physique et de Chimie Industrielles, 10 Rue Vauquelin, F-75231 Paris 05, France
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Abstract
The single and the competitive equilibrium isotherms of nortriptyline and amytriptyline were acquired by frontal analysis (FA) on the C18- bonded discovery column, using a 28/72 (v/v) mixture of acetonitrile and water buffered with phosphate (20 mM, pH 2.70). The adsorption energy distributions (AED) of each compound were calculated from the raw adsorption data. Both the fitting of the adsorption data using multi-linear regression analysis and the AEDs are consistent with a trimodal isotherm model. The single-component isotherm data fit well to the tri-Langmuir isotherm model. The extension to a competitive two-component tri-Langmuir isotherm model based on the best parameters of the single-component isotherms does not account well for the breakthrough curves nor for the overloaded band profiles measured for mixtures of nortriptyline and amytriptyline. However, it was possible to derive adjusted parameters of a competitive tri-Langmuir model based on the fitting of the adsorption data obtained for these mixtures. A very good agreement was then found between the calculated and the experimental overloaded band profiles of all the mixtures injected.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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Asnin L, Götmar G, Guiochon G. Chromatographic behavior of the enantiomers of 2,2,2-trifluoro-1-(9-anthryl)ethanol on a quinidine-carbamate chiral stationary phase. J Chromatogr A 2005; 1091:183-6. [PMID: 16395809 DOI: 10.1016/j.chroma.2005.07.079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The enantioseparation of 2,2,2-trifluoro-1-(9-anthryl)ethanol on silica-bonded quinidine carbamate was examined under linear chromatographic conditions. The significant impact of nonselective adsorption on the retention was demonstrated. The influences of a polar additive in the mobile phase on the retention, the selectivity and the thermodynamic quantities of the retention were measured. A small effect of the pressure on the selectivity and on the accuracy of the thermodynamic measurements was observed.
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Affiliation(s)
- Leonid Asnin
- Department of Chemistry, The University of Tennessee, 552 Buehler Hall, Knoxville, TN 37996-1600, USA
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Gritti F, Guiochon G. Adsorption Mechanism in RPLC. Effect of the Nature of the Organic Modifier. Anal Chem 2005; 77:4257-72. [PMID: 15987135 DOI: 10.1021/ac0580058] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adsorption isotherms of phenol and caffeine were acquired by frontal analysis on two different adsorbents, Kromasil-C18 and Discovery-C18, with two different mobile phases, aqueous solutions of methanol (MeOH/H2O = 40/60 and 30/70, v/v) and aqueous solutions of acetonitrile (MeCN/H2O = 30/70 and 20/80, v/v). The adsorption isotherms are always strictly convex upward in methanol/water solutions. The calculations of the adsorption energy distribution confirm that the adsorption data for phenol are best modeled with the bi-Langmuir and the tri-Langmuir isotherm models for Kromasil-C18 and Discovery-C18, respectively. Because its molecule is larger and excluded from the deepest sites buried in the bonded layer, the adsorption data of caffeine follow bi-Langmuir isotherm model behavior on both adsorbents. In contrast, with acetonitrile/water solutions, the adsorption data of both phenol and caffeine deviate far less from linear behavior. They were best modeled by the sum of a Langmuir and a BET isotherm models. The Langmuir term represents the adsorption of the analyte on the high-energy sites located within the C18 layers and the BET term its adsorption on the low-energy sites and its accumulation in an adsorbed multilayer system of acetonitrile on the bonded alkyl chains. The formation of a complex adsorbed phase containing up to four layers of acetonitrile (with a thickness of 3.4 A each) was confirmed by the excess adsorption isotherm data measured for acetonitrile on Discovery-C18. A simple interpretation of this change in the isotherm curvature at high concentrations when methanol is replaced with acetonitrile as the organic modifier is proposed, based on the structure of the interface between the C18 chains and the bulk mobile phase. This new model accounts for all the experimental observations.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA
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Abstract
The compressibilities of aqueous solutions of methanol or acetonitrile containing 0, 20, 40, 60, 80 and 100% (v/v) organic solvent were measured with a dynamic chromatographic method. The elution volumes of thiourea samples (2 microL) in these solutions were measured at different average column pressures, adjusted by placing suitable capillary restrictors on-line, after the detector. The reproducibility of the measurements was better than 0.2%. In the range of average pressures studied (10-350 bar), the maximum change in elution volume of thiourea is 1.3% (in pure water) and 4.0% (in pure methanol). This difference is due to the different compressibilities of these pure solvents. For mixtures, the plots of the elution volume of thiourea versus the pressure are convex downward, which is inconsistent with the opposite curvature predicted by the classical Tait model of liquid compressibility. This difference is explained by the variation of the amount of thiourea adsorbed with the pressure. The deconvolution of the two effects, adsorption of thiourea and solvent compressibility, allows a fair and consistent determination of the compressibilities of the methanol-water mixtures. A column packed with non-porous silica particles was also used to determine the compressibility of methanol-water and acetonitrile-water mixtures. A negative deviation by respect to ideal behavior was observed.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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Gritti F, Martin M, Guiochon G. Influence of pressure on the properties of chromatographic columns. J Chromatogr A 2005; 1070:13-22. [PMID: 15861783 DOI: 10.1016/j.chroma.2005.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C18-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (<0.001%). These predictions agree well with the results of experimental measurements that were performed on columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C18 (10% carbon) and the Symmetry-C18 (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C18-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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Gritti F, Guiochon G. Effect of the flow rate on the measurement of adsorption data by dynamic frontal analysis. J Chromatogr A 2005; 1069:31-42. [PMID: 15844481 DOI: 10.1016/j.chroma.2004.08.129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The adsorption data of propyl benzoate were acquired by frontal analysis (FA) on a Symmetry-C18 column, using a mixture of methanol (65%, v/v) and water as the mobile phase, at three different flow rates, 0.5, 1.0 and 2.0 mL/min. The exact flow rates Fv were measured by collecting the mobile phase in volumetric glasses (deltaFv / Fv < or = 0.2%). The extra-column volumes and the column hold-up volume were accurately measured at each flow rate by tracer injections. The detailed effect of the flow rate on the value of the amount adsorbed was investigated. The best isotherm model accounting for the adsorption data was the same BET isotherm model at all three flow rates. Only slight differences (always less than 5%) were found between the three different sets of isotherm parameters (saturation capacity, q(s), equilibrium constant on the adsorbent, b(s) and equilibrium constant on successive layers of propyl benzoate, bL). The reproducibility of the same isotherm parameters measured by the inverse method (IM) is less satisfactory, leading to R.S.D.s of up to 10%. A flow rate increase is systematically accompanied by a slight increase of the amount adsorbed. This phenomenon is consistent with the influence of the pressure on the equilibrium constant of adsorption due to the difference between the partial molar volumes of the solute and the adsorbate. The larger average pressure along the column that is required to achieve a larger flow rate causes a larger amount of solute to be adsorbed on the column at equilibrium. This result comforts the high sensitivity and versatility of the FA method for isotherm determination under any kind of situation.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996-1600, USA
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Gritti F, Guiochon G. Effect of the Surface Heterogeneity of the Stationary Phase on the Range of Concentrations for Linear Chromatography. Anal Chem 2005; 77:1020-30. [PMID: 15858981 DOI: 10.1021/ac040163w] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The range of sample sizes within which linear chromatographic behavior is achieved in a column depends on the surface heterogeneity of the RPLC adsorbents. Two widely different commercial adsorbents were tested, the end-capped XTerra-C18 and the non-end-capped Resolve-C18. Adsorption isotherm data of caffeine were acquired by frontal analysis. These data were modeled and used to calculate the adsorption energy distribution (AED). This double analysis informs on the degree of surface heterogeneity. The best adsorption isotherm models are the bi-Langmuir and the tetra-Langmuir isotherms for XTerra and Resolve, respectively. Their respective AEDs are bimodal and quadrimodal distributions. This interpretation of the results and the actual presence of a low density of high-energy adsorption sites on Resolve-C18 were validated by measuring the dependence of the peak retention times on the size of caffeine samples (20-microL volume, concentrations 10, 1, 0.1, 1 x 10(-2), 1 x 10(-3), 1 x 10(-4), and 1 x 10(-5) g/L). The experimental chromatograms agree closely with the band profiles calculated from the best isotherms. On Resolve-C18, the retention time decreases by 40% when the sample concentration is increased from 1 x 10(-5) to 10 g/L. The decrease is only 10% for Xterra-C18 under the same conditions. The upper limit for linear behavior is 1 x 10(-4) g/L for the former adsorbent and 0.01 g/L for the latter. The presence of a few high-energy adsorption sites on Resolve-C18, with an adsorption energy 20 kJ/mol larger than that of the low-energy sites while the same difference on Xterra is only 5 kJ/mol, explains this difference. The existence of adsorption sites with a very high energy for certain compounds affects the reproducibility of their retention times and a rapid loss of efficiency in a sample size range within which linear behavior is incorrectly anticipated.
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Affiliation(s)
- Fabrice Gritti
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996-1600, USA
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