1
|
Cecil T, Bautista J, Collinson MM, Rutan SC. Preparation and characterization of stationary phase gradients on C8 liquid chromatography columns. J Chromatogr A 2024; 1727:464974. [PMID: 38761702 DOI: 10.1016/j.chroma.2024.464974] [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: 02/23/2024] [Revised: 05/02/2024] [Accepted: 05/06/2024] [Indexed: 05/20/2024]
Abstract
Continuous C8 stationary phase gradients are created on commercial Waters Symmetry Shield RP8 columns by strategically cleaving the C8 moieties in a time-dependent fashion. The method relies on the controlled infusion of a trifluoroacetic acid/water/acetonitrile solution through the column to cleave the organic functionality (e.g., C8) from the siloxane framework. The bond cleavage solution is reactive enough to cleave the functional groups, even with polar groups embedded within the stationary phase to protect the silica. Both the longitudinal and radial heterogeneity were evaluated by extruding the silica powder into polyethylene tubing and evaluating the percent carbon content in the different sections using thermogravimetric analysis (TGA). TGA analysis shows the presence of a stationary phase gradient in the longitudinal direction but not in the radial direction. Two different gradient profiles were formed with good reproducibility by modifying the infusion method: one exhibited an 'S'-shaped gradient while the other exhibited a steep exponential-like gradient. The gradients were characterized chromatographically using test mixtures, and the results showed varied retention characteristics and an enhanced ability to resolve nicotine analytes.
Collapse
Affiliation(s)
- Thomas Cecil
- Department of Chemistry, Virginia Commonwealth University, Box 842006, Richmond, VA 23284-2006, USA
| | - Judith Bautista
- Dow Chemical, 230 Abner Jackson Pkwy, Lake Jackson, TX 77566, USA
| | - Maryanne M Collinson
- Department of Chemistry, Virginia Commonwealth University, Box 842006, Richmond, VA 23284-2006, USA.
| | - Sarah C Rutan
- Department of Chemistry, Virginia Commonwealth University, Box 842006, Richmond, VA 23284-2006, USA
| |
Collapse
|
2
|
Jaekel A, Legelli M, Wirtz M, Meyer D, Schräder N, Streckel K, Lamotte S. Selectivity optimization in liquid chromatography via stationary phase tuning. J Sep Sci 2023; 46:e2300204. [PMID: 37568243 DOI: 10.1002/jssc.202300204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 07/28/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023]
Abstract
In striving for the best possible separation, the selectivity of stationary phases as an optimization parameter is often underestimated although there are many ways to influence this powerful tool. This review serves to provide an insight into the various ways of adapting the selectivity of a separation in liquid chromatography. Approaches via temperature and flow rate tuning are discussed as a basis followed by focusing on the stationary phase as the superior optimization parameter. Highly selective stationary phases hereby provide an advantage for groups of similar analytes. For more complex mixtures, separations can be improved using mixed-mode technologies where different retention mechanisms are combined. Serial coupling, mixed-bed columns, and stationary phase optimized selectivity liquid chromatography provide solutions to various degrees. Finally, the advantages of stationary phase tuning over adaption of mobile phase and/or temperature are presented in terms of optimum application range.
Collapse
Affiliation(s)
- Alexander Jaekel
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Rheinbach, Germany
| | - Mo Legelli
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Rheinbach, Germany
| | - Michaela Wirtz
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Rheinbach, Germany
| | - Daniel Meyer
- Department of Analytical and Material Science, BASF SE, Ludwigshafen, Germany
| | - Nicole Schräder
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Rheinbach, Germany
| | - Kevin Streckel
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Rheinbach, Germany
| | - Stefan Lamotte
- Department of Analytical and Material Science, BASF SE, Ludwigshafen, Germany
| |
Collapse
|
3
|
Gong X, Chen W, Zhang K, Li T, Song Q. Serially coupled column liquid chromatography: An alternative separation tool. J Chromatogr A 2023; 1706:464278. [PMID: 37572536 DOI: 10.1016/j.chroma.2023.464278] [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: 05/30/2023] [Revised: 07/20/2023] [Accepted: 08/02/2023] [Indexed: 08/14/2023]
Abstract
Despite the rapid development of liquid chromatography (LC) in recent decades, it remains a challenge to achieve the desired chromatographic separation of complex matrices using a single column. Multi-column LC techniques, particularly serially coupled column LC (SCC-LC), have emerged as a promising solution to overcome this challenge. While more attention has been focused on heart-cutting or comprehensive two-dimensional LC, reviews specifically focusing on SCC-LC, which offers advantages in terms of precision and facile instrumentation, are scarce. Here, our concerns are devoted to the progress summary regarding the instrumentation and applications of SCC-LC. Emphasis is placed on column selection aiming to enlarge peak capacity, selectivity, or both through the optimization of combination types (e.g. RPLC-RPLC, -RPLC-HILIC, and achiral-chiral LC), connection devices (e.g. zero dead volume connector, tubing, and T-type connector), elution program (i.e. isocratic or gradient) and detectors (e.g. mass spectrometer, ultraviolet detector, and fluorescence detector). The application of SCC-LC in pharmaceutical, biological, environmental, and food fields is also reviewed, and future perspectives and potential directions for SCC-LC are discussed. We envision that the review can give meaningful information to analytical scientists when facing heavy chromatographic separation tasks for complicated matrices.
Collapse
Affiliation(s)
- Xingcheng Gong
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Wei Chen
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Ke Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Ting Li
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Qingqing Song
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, China.
| |
Collapse
|
4
|
Are Two Liquid Chromatography Columns in Tandem Better Than One?: Answers from the Hydrophobic Subtraction Model. J Chromatogr A 2022; 1668:462890. [DOI: 10.1016/j.chroma.2022.462890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 11/19/2022]
|
5
|
Codesido S, Guillarme D, Fekete S. Algorithms to optimize multi-column chromatographic separations of proteins. J Chromatogr A 2020; 1637:461838. [PMID: 33422794 DOI: 10.1016/j.chroma.2020.461838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 10/22/2022]
Abstract
The goal of this work was to provide a technical solution for the automated optimization of multi-column systems for protein separation and fractionation. Both algorithm and a software that can be downloaded are provided. In this algorithm, the length and order of the individual column segments can be considered. Various solutions are provided by the algorithm, including i) to obtain uniform peak distribution, ii) to park the different species at the inlet of the individual column segments, and iii) to elute all species as a single peak. Two representative examples are presented, showing the possibility to obtain uniform selectivity between monoclonal antibody (mAb) sub-units, and the on-column fractioning of intact mAbs.
Collapse
Affiliation(s)
- Santiago Codesido
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland; School of Pharmaceutical Sciences, University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland
| | - Davy Guillarme
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland; School of Pharmaceutical Sciences, University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland
| | - Szabolcs Fekete
- Institute of Pharmaceutical Sciences of Western Switzerland (ISPSO), University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland; School of Pharmaceutical Sciences, University of Geneva, CMU-Rue Michel Servet 1, 1211, Geneva 4, Switzerland.
| |
Collapse
|
6
|
Haddad PR, Taraji M, Szücs R. Prediction of Analyte Retention Time in Liquid Chromatography. Anal Chem 2020; 93:228-256. [DOI: 10.1021/acs.analchem.0c04190] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Paul R. Haddad
- Australian Centre for Research on Separation Science, School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, Australia 7001
| | - Maryam Taraji
- Australian Centre for Research on Separation Science, School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, Australia 7001
- The Australian Wine Research Institute, P.O. Box 197, Adelaide, South Australia 5064, Australia
- Metabolomics Australia, P.O. Box 197, Adelaide, South Australia 5064, Australia
| | - Roman Szücs
- Pfizer R&D UK Limited, Ramsgate Road, Sandwich CT13 9NJ, U.K
- Department of Analytical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská Dolina CH2, Ilkovičova 6, SK-84215 Bratislava, Slovakia
| |
Collapse
|
7
|
Navarro-Huerta J, Carrasco-Correa E, Torres-Lapasió J, Herrero-Martínez J, García-Alvarez-Coque M. Modelling retention and peak shape of small polar solutes analysed by nano-HPLC using methacrylate-based monolithic columns. Anal Chim Acta 2019; 1086:142-155. [DOI: 10.1016/j.aca.2019.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 07/23/2019] [Accepted: 08/06/2019] [Indexed: 12/15/2022]
|
8
|
Codesido S, Rudaz S, Veuthey JL, Guillarme D, Desmet G, Fekete S. Impact of particle size gradients on the apparent efficiency of chromatographic columns. J Chromatogr A 2019; 1603:208-215. [DOI: 10.1016/j.chroma.2019.06.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/24/2019] [Accepted: 06/24/2019] [Indexed: 10/26/2022]
|
9
|
Cain CN, Forzano AV, Rutan SC, Collinson MM. Experimental- and simulation-based investigations of coupling a mobile phase gradient with a continuous stationary phase gradient. J Chromatogr A 2019; 1602:237-245. [PMID: 31147155 DOI: 10.1016/j.chroma.2019.05.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/12/2019] [Accepted: 05/18/2019] [Indexed: 12/23/2022]
Abstract
This work seeks to explore and understand the effects of column orientation and degree of modification of continuous stationary phase gradient columns under a mobile phase gradient using both simulations and experiments. Peak parameters such as retention times, peak widths and resolution are obtained for five phenolic compounds on a C18-silica gradient stationary phase. Simulations show that peak widths for the solutes are dependent upon the fractional composition of C18 and orientation of the stationary phase gradient when coupled to a mobile phase gradient. Also, when compared to a simulated uniform mixed-mode column, peak widths reach a minimum on the gradient column with a coverage higher than 50% C18 where the column is oriented to have the C18 dense region at the end. Experimentally, continuous stationary phase gradients were fabricated to have a total C18 composition of 78% of the original uniform column with an exponential profile using a previously described destructive controlled rate infusion method. Under gradient mobile phase conditions, experimental retention times for the gradient column showed a significant increase compared to the original 100% C18 column. Simulations with a similar C18 composition, however, predicted decreased retention times from the original C18 column. A statistical increase in the retention time of protocatechuic acid and decrease in the peak width of tyrosol, caffeic acid, and coumaric acid were noted when the gradient column was oriented to have the C18 dense region located near the detector. Collectively, combining gradients in both the mobile and stationary phases can yield interesting neighboring ligand effects and peak broadening/focusing effects.
Collapse
Affiliation(s)
- Caitlin N Cain
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA, 23284-2006, USA
| | - Anna V Forzano
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA, 23284-2006, USA
| | - Sarah C Rutan
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA, 23284-2006, USA.
| | - Maryanne M Collinson
- Department of Chemistry, Virginia Commonwealth University, 1001 W. Main St., Richmond, VA, 23284-2006, USA.
| |
Collapse
|
10
|
Estimation of peak capacity based on peak simulation. J Chromatogr A 2018; 1574:101-113. [DOI: 10.1016/j.chroma.2018.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/05/2018] [Accepted: 09/06/2018] [Indexed: 02/06/2023]
|
11
|
Cain CN, Forzano AV, Rutan SC, Collinson MM. Destructive stationary phase gradients for reversed-phase/hydrophilic interaction liquid chromatography. J Chromatogr A 2018; 1570:82-90. [DOI: 10.1016/j.chroma.2018.07.073] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/24/2018] [Accepted: 07/26/2018] [Indexed: 02/05/2023]
|
12
|
Jeong LN, Rutan SC. Simulation of elution profiles in liquid chromatography – III. Stationary phase gradients. J Chromatogr A 2018; 1564:128-136. [DOI: 10.1016/j.chroma.2018.06.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 06/03/2018] [Accepted: 06/04/2018] [Indexed: 02/07/2023]
|
13
|
Alvarez-Segura T, Torres-Lapasió JR, García-Alvarez-Coque MC. Updating chromatographic predictions by accounting ageing for single and tandem columns. J Sep Sci 2018; 41:2719-2730. [DOI: 10.1002/jssc.201800264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/18/2018] [Accepted: 04/26/2018] [Indexed: 11/11/2022]
|
14
|
Alvarez-Segura T, Camacho-Molinero C, Torres-Lapasió JR, García-Alvarez-Coque MC. Analysis of amino acids using serially coupled columns. J Sep Sci 2017; 40:2741-2751. [PMID: 28520236 DOI: 10.1002/jssc.201700334] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 11/10/2022]
Abstract
Single conventional columns in reversed-phase liquid chromatography are insufficient for analysing the isoindoles of primary amino acids due to their limited functionality. An interesting possibility for increasing the separation power is the combination of several columns of different nature, where the length is modified by coupling small segments. This approach may require a considerable investment to have multiple lengths for each stationary phase. However, the combination of only two columns of fixed length can be enough to resolve satisfactorily relatively complex mixtures, provided that an optimised gradient program is applied. In this work, a mixture of 19 primary amino acid isoindoles found in proteins was analysed. Four stationary phases were assayed: C18, pentafluorophenyl-C18, C4 and cyano. The mixture of isoindoles was successfully resolved in practical times using a pentafluorophenyl-C18 column coupled to a C4 column, in spite of the extremely poor performance obtained when each column is used isolatedly, independently of the length. The extreme diversity in the polarities of the isoindoles and the need of extrapolating the retention behaviour in certain regions of the solvent content domain makes the modelling of the retention behaviour of the isoindoles particularly difficult. Nevertheless, the predicted optimal separations were very satisfactory.
Collapse
|
15
|
Stationary phase modulation in liquid chromatography through the serial coupling of columns: A review. Anal Chim Acta 2016; 923:1-23. [DOI: 10.1016/j.aca.2016.03.040] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/17/2016] [Accepted: 03/21/2016] [Indexed: 01/22/2023]
|
16
|
A chromatographic objective function to characterise chromatograms with unknown compounds or without standards available. J Chromatogr A 2015. [DOI: 10.1016/j.chroma.2015.07.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
17
|
Alvarez-Segura T, Ortiz-Bolsico C, Torres-Lapasió J, García-Álvarez-Coque M. Serial versus parallel columns using isocratic elution: A comparison of multi-column approaches in mono-dimensional liquid chromatography. J Chromatogr A 2015; 1390:95-102. [DOI: 10.1016/j.chroma.2015.02.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 02/16/2015] [Accepted: 02/18/2015] [Indexed: 11/17/2022]
|
18
|
Ortiz-Bolsico C, Torres-Lapasió J, García-Alvarez-Coque M. Optimisation of gradient elution with serially-coupled columns Part II: Multi-linear gradients. J Chromatogr A 2014; 1373:51-60. [DOI: 10.1016/j.chroma.2014.10.100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/06/2014] [Accepted: 10/25/2014] [Indexed: 10/24/2022]
|
19
|
Delahaye S, Lynen F. Implementing Stationary-Phase Optimized Selectivity in Supercritical Fluid Chromatography. Anal Chem 2014; 86:12220-8. [DOI: 10.1021/ac503313j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Sander Delahaye
- Separation Science Group,
Department of Organic and Macromolecular Chemistry, Universiteit Gent, Krijgslaan
281 S4-bis, B-9000 Gent, Belgium
| | - Frédéric Lynen
- Separation Science Group,
Department of Organic and Macromolecular Chemistry, Universiteit Gent, Krijgslaan
281 S4-bis, B-9000 Gent, Belgium
| |
Collapse
|
20
|
Ortiz-Bolsico C, Torres-Lapasió J, García-Alvarez-Coque M. Optimisation of gradient elution with serially-coupled columns. Part I: Single linear gradients. J Chromatogr A 2014; 1350:51-60. [DOI: 10.1016/j.chroma.2014.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/29/2014] [Accepted: 05/04/2014] [Indexed: 11/30/2022]
|
21
|
Wang C, Tymiak AA, Zhang Y. Optimization and Simulation of Tandem Column Supercritical Fluid Chromatography Separations Using Column Back Pressure as a Unique Parameter. Anal Chem 2014; 86:4033-40. [DOI: 10.1021/ac500530n] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Chunlei Wang
- Bioanalytical and Discovery Analytical Sciences, Research & Development, Bristol-Myers Squibb Company, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| | - Adrienne A. Tymiak
- Bioanalytical and Discovery Analytical Sciences, Research & Development, Bristol-Myers Squibb Company, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| | - Yingru Zhang
- Bioanalytical and Discovery Analytical Sciences, Research & Development, Bristol-Myers Squibb Company, Route 206 and Province Line Road, Princeton, New Jersey 08543, United States
| |
Collapse
|
22
|
Socia A, Foley JP. Sequential elution liquid chromatography can significantly increase the probability of a successful separation by simultaneously increasing the peak capacity and reducing the separation disorder. J Chromatogr A 2014; 1324:36-48. [DOI: 10.1016/j.chroma.2013.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 10/29/2013] [Accepted: 11/12/2013] [Indexed: 10/26/2022]
|
23
|
Kannan B, Nokura K, Alvarez JC, Higgins DA, Collinson MM. Fabrication of surface charge gradients in open-tubular capillaries and their characterization by spatially resolved pulsed streaming potential measurements. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15260-15265. [PMID: 24274139 DOI: 10.1021/la402934m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Surface charge gradients have been formed on the inside surface of 75 μm i.d. silica capillaries via controlled rate infusion using 3-aminopropyltriethoxysilane as the reactive precursor. These 400 mm length gradients have been characterized using spatially resolved streaming potential measurements, from which the zeta potential as a function of distance was determined. The gradient capillaries exhibited a gradual variation in zeta potential from top to bottom, whereas uniformly modified and as-received capillaries were relatively homogeneous along their length. For a gradient prepared with a relatively high concentration of aminosilane, the zeta potential changed over 60 mV from one end of the capillary to the other, yielding a variation in the magnitude of the apparent surface charge of ~7 fold. By changing the concentration of the aminoalkoxysilane and/or the rate of infusion, both the value of the zeta potential (and hence surface charge) and its spatial profile (i.e., rate of change with distance) could be manipulated.
Collapse
Affiliation(s)
- Balamurali Kannan
- Department of Chemistry, Virginia Commonwealth University , Richmond, Virginia 23284-2006, United States
| | | | | | | | | |
Collapse
|
24
|
Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: State of the art and new results. J Chromatogr A 2013; 1314:142-53. [DOI: 10.1016/j.chroma.2013.09.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 11/18/2022]
|
25
|
Chromatographic resolution of closely related species: Separation of warfarin and hydroxylated isomers. J Chromatogr A 2013; 1314:266-75. [DOI: 10.1016/j.chroma.2013.07.092] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/19/2013] [Accepted: 07/23/2013] [Indexed: 11/22/2022]
|
26
|
Simultaneous optimization of mobile phase composition, column nature and length to analyse complex samples using serially coupled columns. J Chromatogr A 2013; 1317:39-48. [DOI: 10.1016/j.chroma.2013.06.035] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/29/2013] [Accepted: 06/14/2013] [Indexed: 11/20/2022]
|