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Atia MA, Smejkal P, Gupta V, Haddad PR, Breadmore MC. Chemical vapour deposition in narrow capillaries: Electro-osmotic flow control in capillary electrophoresis. Anal Chim Acta 2023; 1280:341847. [PMID: 37858546 DOI: 10.1016/j.aca.2023.341847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/05/2023] [Accepted: 09/23/2023] [Indexed: 10/21/2023]
Abstract
BACKGROUND In capillary electrophoresis (CE), the inner surface of fused-silica capillaries is commonly covalently modified with liquid silanes to control electroosmotic flow (EOF). This liquid phase deposition (LPD) approach is challenging for long and narrow-diameter capillaries (≥1 m, ≤25 μm ID) inhibiting commercial production. Here, we use chemical vapour deposition (CVD) to covalently modify capillaries with different silanes. Using a home-built CVD device, capillaries were modified with neutral (3-glycidyloxypropyl) trimethoxysilane (GPTMS), the weak base (3-aminopropyl) trimethoxysilane (APTMS), the weak acid 3-mercaptopropyltrimethoxysilane (MPTMS) and the neutral hydrophobic trichloro(1H,1H,2H,2H-perfluorooctyl) silane (PFOCTS). Gas-phase modification of GPTMS with acid and ammonia allowed further modification of the surface prior to molecular layer deposition (MLD) of poly(p-phenylene terephthalamide) (PPTA) using the self-limiting sequential reaction between terephthalaldehyde (TA) and p-phenylenediamine (PD) vapours. RESULTS Capillaries coated with GPTMS by CVD showed a greater reduction in EOF at all pH values than the conventional LPD. APTMS showed a reduction of the EOF at pH 9, with EOF reversal observed below pH 6. MPTMS provided a slightly lower EOF than an unmodified capillary at high pH, and a slightly higher EOF at lower pH. PFOCTS provided the most consistent EOF as a function of pH. The deposition of successive layers of PPTA resulted in increased surface coverage of the polymer and a greater reduction in EOF at pH higher than 5. The stability of a 10 μm ID GPTMS coated capillary was tested at pH 8.8 in a 200 mM CHES/Tris BGE for the separation of inorganic anions. Over 1.5 months of continuous operation (≈4130 runs), the reproducibility of the apparent mobilities for chloride, nitrite, nitrate and sulfate were 2.43%, 2.56%, 2.63% and 3.05%, respectively. The intra-day and inter-day column-to-column reproducibility and batch-to-batch reproducibility for all the coated capillaries ranged between 0.34% and 3.95%. SIGNIFICANCE The study demonstrates the superior performance of CVD coating for suppressing the EOF compared to LPD allowing the easy modification of long lengths of narrow capillary. The variation in silane, and the ability of MLD to modify and control the surface chemistry, provides a simple and facile method for surface modification. The stability of these coatings will allow long-term capillary electrophoresis monitoring of water chemistry, such as for monitoring fertiliser run-off in natural waters.
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Affiliation(s)
- Mostafa A Atia
- Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, 7001, Australia; Department of Analytical Chemistry, Faculty of Pharmacy Helwan University, 11795, Cairo, Egypt.
| | - Petr Smejkal
- Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, 7001, Australia.
| | - Vipul Gupta
- Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, 7001, Australia.
| | - Paul R Haddad
- Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, 7001, Australia.
| | - Michael C Breadmore
- Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania, 7001, Australia.
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Kaczmarczyk N, Ciżewska J, Treder N, Miękus N, Plenis A, Kowalski P, Roszkowska A, Bączek T, Olędzka I. The critical evaluation of the effects of imidazolium-based ionic liquids on the separation efficiency of selected biogenic amines and their metabolites during MEKC analysis. Talanta 2022; 238:122997. [PMID: 34857330 DOI: 10.1016/j.talanta.2021.122997] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 10/14/2021] [Accepted: 10/23/2021] [Indexed: 11/15/2022]
Abstract
Ionic liquids (ILs) such as imidazole can be used to prevent the sorption of analytes onto the quartz walls of the capillary. Coating the capillary wall with a cation layer increases its surface stability, consequently improving the repeatability of separation process. Currently, examining the effects of dynamic coatings on the capillary wall is an emerging trend in capillary electrophoresis (CE) research. This study uses micellar electrokinetic chromatography (MEKC) to evaluate how ILs in the background electrolyte (BGE) affect the separation efficiency of biogenic amines (BAs). Specifically, this research focuses on 12 ILs built from cations containing an imidazole ring with different alkyl substituents and anions, as well as one IL containing a pyridinium cation with tetrafluoroborate anion. All analyzed ILs, which were added to the BGE in concentrations ranging from 1 to 20 mM, were tested for their ability to improve the electrophoretic separation of selected BAs, namely: homovanillic acid (HVA), vanililmandelic acid (VMA), dihydroxyphenylglicol (DHPG), 3-metoxy-4-hydroxyphenyl glicol (MHPG), normetanephrine (NM), metanephrine (M), and dihydroxyphenylacetic acid (DOPAC). The results showed that the most effective ILs added to the BGE were those with a chloride anion (1-hexyl-3-methylimidazolium chloride [HMIM+Cl-] and 1-ethyl-3-methylimidazolium chloride [EMIM+Cl-]) and those with a tetrafluoroborate anion (1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM + BF4-]). Improved separation efficiency was also obtained for the BGE containing 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM + PF6-]. On the other hand, ILs with trifluoromethanesulfonate [OTf-] or bis(trifluoromethylsulfonyl)imide [NTf2-] anions, even at low concentrations in the BGE, disturbed the flow of current through the capillary and worsened the separation process. Overall, this study provides a critical evaluation of the impact of different types and concentrations of ILs on the performance of the MEKC method during the analysis of selected BAs.
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Affiliation(s)
- Natalia Kaczmarczyk
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Julita Ciżewska
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Natalia Treder
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Natalia Miękus
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Alina Plenis
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Piotr Kowalski
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Anna Roszkowska
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Tomasz Bączek
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland
| | - Ilona Olędzka
- Department of Pharmaceutical Chemistry, Medical University of Gdańsk, al. Gen. J. Hallera 107, 80-416, Gdańsk, Poland.
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Li P, Wang L, Guo R, Feng H, Ji Y, Lim SY, Ng BH, Laserna AKC, Khan S, Chen SM, Li SFY. Cross-identification of N-Glycans by CE-LIF using two capillary coatings and three labeling dyes. Talanta 2021; 239:123061. [PMID: 34809984 DOI: 10.1016/j.talanta.2021.123061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 11/01/2021] [Accepted: 11/10/2021] [Indexed: 01/21/2023]
Abstract
Recombinant protein biopharmaceuticals comprise a significant portion of the current drug development landscape. The glycosylation profile of these proteins is a key quality parameter as it can affect their safety, efficacy, and stability. However, glycan analysis is challenging because of the complexity of their structures. To overcome this challenge in achieving accurate glycan identification, cross-identification of N-Glycans by CE-LIF method using two capillary coatings and three labeling dyes was developed in this work. This work explored whether complementary separation capabilities can be achieved using homemade polyvinyl alcohol (PVA) coating and commercial Guarant™ (Guarant) coating in the analysis of N-glycans. Similar separation profiles were observed using the two capillary coatings, and hence the N-glycan GU databases generated by these coatings were comparable and complementary. The performance of cross-validation by labeling with three fluorescent dyes indicated that low covariance of APTS and Turquoise™ labeling can be obtained, and hence these two labeling mechanisms provided better accuracy for the identification of glycans. Superior reproducibility with RSDs less than 1% for all target glycan standards was achieved by the internal standards (IS) method using maltodextrin ladders as additives in the separation buffer. The developed CE-LIF analysis method was applied to the identification of N-glycans in IgG samples.
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Affiliation(s)
- Pingjing Li
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, Hainan, 572000, China; NUS Environmental Research Institute, National University of Singapore, T-Lab Building, 5A Engineering Drive 1, 117411, Singapore
| | - Lulu Wang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | - Rui Guo
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | - Huatao Feng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | - Ya Ji
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | - Si Ying Lim
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | - Bao Hui Ng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543
| | | | - Shaheer Khan
- Thermo Fisher Scientific, 180, Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Shiaw-Min Chen
- Thermo Fisher Scientific, 180, Oyster Point Blvd, South San Francisco, CA, 94080, USA
| | - Sam Fong Yau Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore S117543; NUS Environmental Research Institute, National University of Singapore, T-Lab Building, 5A Engineering Drive 1, 117411, Singapore.
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Dziomba S, Wysocka M, Jońca J, Sola L, Steć A, Waleron K, Wielgomas B. Investigation of selected parameters of capillary zone electrophoresis method for analysis of isolates of outer membrane vesicles. Electrophoresis 2021; 42:2010-2017. [PMID: 34015152 DOI: 10.1002/elps.202000360] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 05/05/2021] [Accepted: 05/11/2021] [Indexed: 11/05/2022]
Abstract
The capillary zone electrophoresis (CZE) has recently been proposed by our group as a novel technique for outer membrane vesicles (OMVs) characterization (J. Chromatography 1621 (2020) 461047). In present work the impact of selected parameters of CZE method on OMVs isolates analysis was assessed. It was shown that the extension of sample injection plug length significantly improves the detectability of macromolecular aggregates in CZE. Moreover, a negligible adsorption of OMVs to both uncoated and polymer-modified (poly(DMA-GMA-MAPS)) capillary walls was proven. Finally, the relaxation effect as well as deformation/polarization of vesicles were demonstrated to affect OMVs electrophoretic mobility. The significance of these findings was discussed.
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Affiliation(s)
- Szymon Dziomba
- Department of Toxicology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Magdalena Wysocka
- Department of Toxicology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Joanna Jońca
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Laura Sola
- Istituto di Scienze e Tecnologie Chimiche "G. Natta", CNR, Italy
| | - Aleksandra Steć
- Department of Toxicology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Krzysztof Waleron
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
| | - Bartosz Wielgomas
- Department of Toxicology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
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Safari M, Yamini Y. Application of magnetic nanomaterials in magnetic in-tube solid-phase microextraction. Talanta 2021; 221:121648. [PMID: 33076165 DOI: 10.1016/j.talanta.2020.121648] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 12/12/2022]
Abstract
Development of magnetic nanomaterials has greatly promoted the innovation of in-tube solid-phase microextraction. This review article gives an insight into recent advances in the modifications and applications of magnetic nanomaterials for in-tube solid-phase microextraction. Also, different magnetic nanomaterials which have recently been utilized as in-tube solid-phase microextraction sorbents are classified. This study shows that magnetic nanomaterials have gained significant attention owing to large specific surface area, selective absorption, and surface modification. Magnetic in-tube solid-phase microextraction has been applied for the analysis of food samples, biological, and environmental. However, for full development of magnetic in-tube SPME, effort is still needed to overcome limitations, such as mechanical stability, selectivity and low extraction efficiency. To achieve these objectives, research on magnetic in-tube SPME is mainly focused in the preparation of new extractive phases.
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Affiliation(s)
- Meysam Safari
- Department of Basic Sciences, Kermanshah University of Technology, Kermanshah, Iran
| | - Yadollah Yamini
- Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran.
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Xu X. Capillary Electrophoresis-Mass Spectrometry for Cancer Metabolomics. Adv Exp Med Biol 2021; 1280:189-200. [PMID: 33791983 DOI: 10.1007/978-3-030-51652-9_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
This chapter presents the fundamentals, instrumentation, methodology, and applications of capillary electrophoresis-mass spectrometry (CE-MS) for cancer metabolomics. CE offers fast and high-resolution separation of charged analytes from a very small amount of sample. When coupled to MS, it represents a powerful analytical technique enabling identification and quantification of metabolites in biological samples. Several issues need to be addressed when combining CE with MS, especially the interface between CE and MS and the selection of a proper separation methodology, sample pretreatment, and capillary coatings. We will discuss these aspects of CE-MS and detail representative applications for cancer metabolomic analysis.
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Affiliation(s)
- Xiangdong Xu
- School of Public Health and Key Laboratory of Environment and Human Health, Hebei Medical University, Shijiazhuang, China.
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Yu B, Peng Q, Usman M, Ahmed A, Chen Y, Chen X, Wang Y, Shen Y, Cong H. Preparation of photosensitive diazotized poly (vinyl alcohol-b-styrene) covalent capillary coatings for capillary electrophoresis separation of proteins. J Chromatogr A 2019; 1593:174-182. [PMID: 30745136 DOI: 10.1016/j.chroma.2019.02.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/29/2019] [Accepted: 02/02/2019] [Indexed: 11/13/2022]
Abstract
In this paper, we have developed a novel method for the preparation of covalently connected capillary coatings in which diazotized poly (vinyl alcohol-b-styrene) (diazo-P(VA-b-St)) was used as a photosensitive coating agent. Firstly, the diazo-P(VA-b-St) coating was self-assembled on the inner surface of the capillary, and then irradiated by ultraviolet (UV) light to convert the ionic bonding into covalent bonding through the unique photochemical reaction of diazo groups. The covalently connected coatings inhibited the protein adsorption on the inner surface of the capillary, as a result, the baseline protein separation of ribonuclease A (RNase A), lysozyme (Lyz) and bovine serum albumin (BSA) were attained by utilizing the capillary electrophoresis (CE). The covalently connected diazo-P(VA-b-St) capillary coatings have greater CE separation performance with magnificent repeatability and enhanced stability, when compared with non-covalently coated or bare capillaries. This strategy to synthesize photosensitive diazo-P(VA-b-St) capillary coatings for their use in capillary electrophoresis separation of proteins is highly environment-friendly as it does not involve the use of extremely noxious and moisture penetrating coatings of silane.
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Affiliation(s)
- Bing Yu
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China; Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao University, Qingdao, 266071, China
| | - Qiaohong Peng
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Muhammad Usman
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Adeel Ahmed
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Yao Chen
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Xin Chen
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Yifan Wang
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Youqing Shen
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China
| | - Hailin Cong
- Institute of Biomedical Materials and Engineering, College of Chemistry and Chemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao, 266071, China; Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao University, Qingdao, 266071, China.
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Song WF, Zhao QL, Zhou XJ, Zhang LS, Huang YP, Liu ZS. A star-shaped molecularly imprinted polymer derived from polyhedral oligomeric silsesquioxanes with improved site accessibility and capacity for enantiomeric separation via capillary electrochromatography. Mikrochim Acta 2018; 186:22. [PMID: 30554280 DOI: 10.1007/s00604-018-3151-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 12/06/2018] [Indexed: 10/27/2022]
Abstract
A star-shaped molecularly imprinted coating was prepared starting from octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS). It possesses a relatively open structure and has good site accessibility and a larger capacity even at lower cross-linking. The imprinted coating was prepared from S-amlodipine (S-AML) as the template and analyte, Ov-POSS as the cross-linker, and methacrylic acid as the functional monomer. The preparation and chromatographic parameters were optimized, including ratio of template to functional monomer, apparent cross-linking degree, pH value, ACN content and salt concentration in the mobile phase. The best resolution in enantiomer separation by means of capillary electrochromatography reaches a value of 33. A good recognition ability (α = 2.60) was obtained and the column efficiency for S-AML was 54,000 plates m-1. The use of Ov-POSS as a cross-linker significantly improves the column capacity and thus the detection sensitivity. The results show that Ov-POSS is an effective cross-linker for the preparation of imprinted polymers with good accessibility and large capacity. Graphical abstract Schematic presentation of the preparation of star-shaped imprinted polymer using octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS) and by using methacrylic acid (MAA) as functional monomer. The best enantiometric resolution (33) for amlodipine (AML) can be achieved in capillary chromatography (CEC).
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Nowak PM, Woźniakiewicz M, Gładysz M, Janus M, Kościelniak P. Improving repeatability of capillary electrophoresis-a critical comparison of ten different capillary inner surfaces and three criteria of peak identification. Anal Bioanal Chem 2017; 409:4383-4393. [PMID: 28484810 PMCID: PMC5486911 DOI: 10.1007/s00216-017-0382-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 04/18/2017] [Accepted: 04/25/2017] [Indexed: 01/30/2023]
Abstract
A poor repeatability of migration times caused by the fluctuations of electroosmotic flow (EOF) is an inherent weakness of capillary electrophoresis. Most researchers endeavor to prevent this problem using relative migration times or various capillary coatings which are expensive and not easy in comparison. Herein, we present an original approach to this problem: we apply a model sample designed to induce significant EOF instability, in order to critically compare ten capillary types with different physicochemical characteristics. Moreover, we accompany capillary modification with the evaluation of various criteria of peak identification: migration time, migration times ratio, and electrophoretic mobility. Our results show a great effectiveness of a dynamic coating in the stabilization of migration times, with the average RSD(%) value reduced from 3.5% (bare silica capillary) down to 0.5%. The good outcomes were also obtained for the surfactant-modified silica and amine capillaries. For the capillaries exhibiting significant instability of EOF, electrophoretic mobility turned out to be a more universal and reliable criterion of peak identification than relative migration time. It can be explained by an intrinsic dependency of migration times ratio on EOF change, which should always be considered during the selection of an internal standard.
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Affiliation(s)
- Paweł Mateusz Nowak
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland.
| | - Michał Woźniakiewicz
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Marta Gładysz
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Magdalena Janus
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
| | - Paweł Kościelniak
- Faculty of Chemistry, Department of Analytical Chemistry, Jagiellonian University in Kraków, Ingardena St. 3, 30-060, Kraków, Poland
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Nowak PM, Woźniakiewicz M, Janus M, Kościelniak P. Enhancing effectiveness of capillary electrophoresis as an analytical tool in the supramolecular acidity modification. Anal Bioanal Chem 2017; 409:3633-43. [PMID: 28341986 DOI: 10.1007/s00216-017-0305-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/01/2017] [Accepted: 03/08/2017] [Indexed: 12/15/2022]
Abstract
A strategic modification of acidity (pKa values) by the non-covalent host-guest interactions is one of the most promising concepts in current supramolecular chemistry. This work is aimed at enhancing the effectiveness of capillary electrophoresis (CE) in determination of pKa shifts caused by such interactions and their thermal dependencies crucial in a deep thermodynamic description. We show how to (i) minimize the systematic errors related to Joule heating, (ii) minimize the influence of a voltage ramp time, (iii) speed up pKa shift identification and estimation, (iv) interpret thermal effects related to two overlapped dynamic equilibria, and (v) determine pKa shifts by an alternative spectrophotometric method (CE-DAD). The proposed solutions were implemented to examine the supramolecular pKa shifts of several coumarin derivatives, caused by a variety of structurally different cyclodextrins. It was revealed that a specific host substitution pattern determines the magnitude of apparent pKa shifts. Accordingly, heptakis(2,6-di-O-methyl)-β-cyclodextrin induces the much stronger shifts than both non-methylated-β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin applied at the same concentration. We also show that insofar as the complexation of 4-hydroxycoumarin and its derivative (coumatetralyl) are similarly exothermic, the thermal effects accompanying the deprotonation process are remarkably different for both molecules. The pKa shift induced by complexation with calixarene was also for the first time determined by a CE method. These observations throw a new light on the background of acidity modification and confirm the applicability of CE as an analytical tool.
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Nowak PM, Woźniakiewicz M, Michalik M, Fiedor L, Kościelniak P. Capillary coating as an important factor in optimization of the off-line and on-line MEKC assays of the highly hydrophobic enzyme chlorophyllase. Anal Bioanal Chem 2017; 409:1493-1501. [PMID: 27888314 PMCID: PMC5306352 DOI: 10.1007/s00216-016-0097-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/07/2016] [Accepted: 11/11/2016] [Indexed: 12/15/2022]
Abstract
The choice between bare and coated capillaries is a key decision in the development and use of any methods based on capillary electrophoresis. In this work several permanently and dynamically coated capillaries were successfully implemented in a previously developed micellar electrokinetic chromatography (MEKC) assay of the plant membrane enzyme chlorophyllase. The results obtained demonstrate the rationale behind the use of capillary coating, which is crucial for successful optimization of both the off-line mode and the on-line/electrophoretically mediated microanalysis assay mode. The application of an amine permanently coated capillary (eCAP) is a simple way to significantly increase the repeatability of migration times and peak areas, and to ensure a strong electroosmotic flow that considerably decreases the overall analysis time. A dynamic coating (CEofix) allows one to apply an on-line incubation to control the reaction progress inside the capillary, and to increase the signal-to-noise ratio and peak efficiency. The dynamic coating is possible with use of both the normally applied uncoated silica capillary and the precoated amine capillary, which ensures more repeatable migration times. The strong points of the uncoated silica capillary are its attractive price and wide range of pH that can be applied. The characteristics presented may simplify the choice of capillary modification, especially in the case of hydrophobic analytes, MEKC-based separations, and other enzymatic assays.
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Affiliation(s)
- Paweł Mateusz Nowak
- Faculty of Chemistry, Jagiellonian University in Kraków, Ingardena 3, 30-060, Kraków, Poland.
| | - Michał Woźniakiewicz
- Faculty of Chemistry, Jagiellonian University in Kraków, Ingardena 3, 30-060, Kraków, Poland
| | - Maciej Michalik
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387, Kraków, Poland
| | - Leszek Fiedor
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Kraków, Gronostajowa 7, 30-387, Kraków, Poland
| | - Paweł Kościelniak
- Faculty of Chemistry, Jagiellonian University in Kraków, Ingardena 3, 30-060, Kraków, Poland
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12
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Zhang C, Hage DS. Glycoform analysis of alpha 1-acid glycoprotein by capillary electrophoresis. J Chromatogr A 2016; 1475:102-109. [PMID: 27863712 PMCID: PMC5147584 DOI: 10.1016/j.chroma.2016.11.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/09/2016] [Accepted: 11/10/2016] [Indexed: 11/25/2022]
Abstract
A relatively fast and reproducible CE separation was developed for the glycoform analysis of α1-acid glycoprotein (AGP). Factors that were considered included the pH for this separation and various techniques for coating the capillary and/or to minimize electroosmotic flow and protein adsorption. Optimum resolution of the AGP glycoforms was obtained at pH 4.2 with a running buffer containing 0.1% Brij 35 and by using static and dynamic coatings of PEO on the capillary. These conditions made it possible to separate nine AGP glycoform bands in about 20min. The limit of detection (based on absorbance measurements) ranged from 0.09 to 0.38μM for these AGP glycoform bands, and the linear range extended up to a total AGP concentration of at least 240μM. The migration times for the glycoform bands had typical within-day and day-to-day precisions of ±0.16-0.23% or less, respectively, on a single treated capillary and the variation between capillaries was ±0.56% or less. A charge ladder approach was employed to examine the mass or charge differences in the glycoforms that made up these bands, giving a good fit to a model in which the neighboring bands differed by one charge (e.g., from a sialic acid residue) and had an average mass difference of approximately 0.7-0.9kDa. The approaches used to develop this separation method are not limited to AGP but could be extended to the analysis of other glycoproteins by CE.
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Affiliation(s)
- Chenhua Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA
| | - David S Hage
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588, USA.
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13
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Bodnar J, Hajba L, Guttman A. A fully automated linear polyacrylamide coating and regeneration method for capillary electrophoresis of proteins. Electrophoresis 2016; 37:3154-3159. [PMID: 27731499 DOI: 10.1002/elps.201600405] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 09/09/2016] [Accepted: 09/10/2016] [Indexed: 11/07/2022]
Abstract
Surface modification of the inner capillary wall in CE of proteins is frequently required to alter EOF and to prevent protein adsorption. Manual protocols for such coating techniques are cumbersome. In this paper, an automated covalent linear polyacrylamide coating and regeneration process is described to support long-term stability of fused-silica capillaries for protein analysis. The stability of the resulting capillary coatings was evaluated by a large number of separations using a three-protein test mixture in pH 6 and 3 buffer systems. The results were compared to that obtained with the use of bare fused-silica capillaries. If necessary, the fully automated capillary coating process was easily applied to regenerate the capillary to extend its useful life-time.
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Affiliation(s)
- Judit Bodnar
- MTA-PE Translational Glycomics Research Group, University of Pannonia, Veszprem, Hungary
| | - Laszlo Hajba
- MTA-PE Translational Glycomics Research Group, University of Pannonia, Veszprem, Hungary
| | - Andras Guttman
- MTA-PE Translational Glycomics Research Group, University of Pannonia, Veszprem, Hungary.,Horváth Csaba Memorial Institute for Bioanalytical Research, University of Debrecen, Debrecen, Hungary
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14
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Yu B, Chen X, Cong H, Shu X, Peng Q. Photosensitive diazotized poly(ethylene glycol) covalent capillary coatings for analysis of proteins by capillary electrophoresis. Anal Bioanal Chem 2016; 408:6781-8. [PMID: 27475442 DOI: 10.1007/s00216-016-9804-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/09/2016] [Accepted: 07/18/2016] [Indexed: 11/30/2022]
Abstract
A new method for the fabrication of covalently cross-linked capillary coatings of poly(ethylene glycol) (PEG) is described using diazotized PEG (diazo-PEG) as a new photosensitive coating agent. The film of diazo-PEG depends on ionic bonding and was first prepared on the inner surface of capillary by self-assembly, and ionic bonding was converted into covalent bonding after reaction of ultraviolet light with diazo groups through unique photochemical reaction. The covalently bonded coating impedance adsorption of protein on the central surface of capillary and hence the four proteins ribonuclease A, cytochrome c, bovine serum albumin, and lysosome can be baseline separated by using capillary electrophoresis (CE). The covalently cross-linked diazo-PEG capillary column coatings not only improved the CE separation performance for proteins compared to non-covalently cross-linked coatings or bare capillary but also showed a remarkable chemical solidity and repeatability. Because photosensitive diazo-PEG took the place of the highly noxious and silane moisture-sensitive coating reagents in the fabrication of covalent coating, this technique shows the advantage of being environment-friendly and having a high efficiency for CE to make the covalently bonded capillaries.
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Affiliation(s)
- Bing Yu
- College of Materials Science and Engineering, Qingdao University, Qingdao, Shandong, 266071, China. .,Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao, Shandong, 266071, China.
| | - Xin Chen
- College of Materials Science and Engineering, Qingdao University, Qingdao, Shandong, 266071, China
| | - Hailin Cong
- College of Materials Science and Engineering, Qingdao University, Qingdao, Shandong, 266071, China. .,Laboratory for New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao, Shandong, 266071, China.
| | - Xi Shu
- College of Materials Science and Engineering, Qingdao University, Qingdao, Shandong, 266071, China
| | - Qiaohong Peng
- College of Materials Science and Engineering, Qingdao University, Qingdao, Shandong, 266071, China
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15
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Zhu G, Sun L, Dovichi NJ. Thermally-initiated free radical polymerization for reproducible production of stable linear polyacrylamide coated capillaries, and their application to proteomic analysis using capillary zone electrophoresis-mass spectrometry. Talanta 2016; 146:839-43. [PMID: 26695337 PMCID: PMC4690009 DOI: 10.1016/j.talanta.2015.06.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/01/2015] [Accepted: 06/02/2015] [Indexed: 02/03/2023]
Abstract
Proteomic analysis using capillary zone electrophoresis (CZE) typically is performed with linear polyacrylamide (LPA) coated capillaries. These capillaries both minimize the adsorption of peptides and proteins to the inner wall of the capillary and decrease electroosmosis, which increases the separation capacity. LPA coating protocols were first reported by Hjerten in 1985. Conventional LPA production is based on the use of tetramethylethylenediamine (TEMED) to catalyze the free-radical polymerization that couples acrylamide to a capillary wall that has been pretreated with γ-methacryloxypropyltrimethoxysilane. The treated capillary is filled with a mixture of monomer, TEMED, and ammonium persulfate; free radical polymerization forms the LPA coating. Over many years, we have observed significant variation in the electroosmotic properties of commercial LPA coated capillaries both along the capillary length and between lots. We believe this variation is due to differences in the time between initiation of the reaction and the filling of the capillary. Here, we report a simple method for the generation of very stable and reproducible coatings. In this protocol, the monomer mixture and an ammonium persulfate initiator are introduced into the capillary without TEMED initiator. The mixture is stable and does not begin polymerization at room temperature. The filled capillary is then heated in a water bath to initiate polymerization in a well-controlled manner. A mixture of four standard proteins was used to evaluate the coating performance. Compared with commercialized LPA capillaries, our LPA capillaries generate much better separation performance and superior protein peak shape in CZE analysis. We also analyzed an intact antibody (MW 150K) by CZE-MS with the new LPA capillary in triplicate runs. The intact antibody generated a Gaussian-shaped electrophoresis peak with 1.2% relative standard deviation in migration time and 8.5% in base peak intensity. An automated CZE-MS system was used to generate 97 successive separations of a BSA tryptic digest over a 145-h period. Separation efficiency averaged over 100,000 theoretical plates across this period with no systematic variation. The LPA coating protocol had excellent batch-to-batch reproducibility with relative standard deviation in migration time<7%, and in separation window<1%.
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Affiliation(s)
- Guijie Zhu
- Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, IN 46556, USA
| | - Liangliang Sun
- Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, IN 46556, USA
| | - Norman J Dovichi
- Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame, IN 46556, USA
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16
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Pobozy E, Sentkowska A, Piskor A. Comparison of three modifications of fused-silica capillaries and untreated capillaries for protein profiling of maize extracts by capillary electrophoresis. J Sep Sci 2014; 37:2388-94. [PMID: 24931305 DOI: 10.1002/jssc.201301236] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 12/15/2022]
Abstract
In this work, capillary electrophoresis was applied to protein profiling of fractionated extracts of maize. A comparative study on the application of uncoated fused-silica capillaries and capillaries modified with hydroxypropylmethylcellulose, ω-iodoalkylammonium salt and a commercially available neutral capillary covalently coated with polyacrylamide is presented. The coating stability, background electrolyte composition, and separation efficiency were investigated. It was found that for zeins separation, the most stable and efficient was the capillary coated with polyacrylamide. Finally, the usefulness of these methods was studied for the differentiation of zein fraction in transgenic and nontransgenic maize. Zeins extracted from maize standards containing 0 and 5% m/m genetic modification were successfully separated, but slight differences were observed in terms of the zein content. Albumin and globulin fractions were analyzed with the use of unmodified fused-silica capillary with borate buffer pH 9 and the capillary coated with polyacrylamide with phosphate buffer pH 3. In the albumin fraction, additional peaks were found in genetically modified samples.
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Affiliation(s)
- Ewa Pobozy
- Department of Chemistry, Warsaw University, Warsaw, Poland
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17
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Sáiz J, Mai TD, Hauser PC, García-Ruiz C. Determination of nitrogen mustard degradation products in water samples using a portable capillary electrophoresis instrument. Electrophoresis 2013; 34:2078-84. [PMID: 23686627 DOI: 10.1002/elps.201300054] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 05/10/2013] [Accepted: 05/10/2013] [Indexed: 12/26/2022]
Abstract
In this work, a new purpose-made portable CE instrument with a contactless conductivity detector was used for the determination of degradation products of nitrogen mustards in different water samples. The capillary was coated with poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) to avoid analyte-wall interactions. The coating procedure was studied to obtain the best repeatability of the migration time of the analytes. Four different coating procedures were compared; flushing the capillary with the copolymer at 100 psi for 2 min at 60°C provided the best RSD values (<4%). The analytical method was also optimized. The use of 20 mM of MES adjusted to pH 6.0 with His as running buffer allowed a good baseline separation of the three analytes in different water samples without matrix interferences. The method permitted the detection of the three degradation products down to 5 μM.
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Affiliation(s)
- Jorge Sáiz
- Department of Analytical Chemistry, Multipurpose Building of Chemistry, University of Alcalá, Alcalá de Henares, Madrid, Spain
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18
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Zandkarimi M, Shafaati A, Foroutan SM, A. Lucy C. Improvement of electrophoretic enantioseparation of amlodipine by polybrene. Iran J Pharm Res 2012; 11:129-36. [PMID: 25317194 PMCID: PMC3876563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In chiral and non-chiral electrophoretic resolution of basic drugs, adsorption of analytes to negatively charged capillary wall could lead to poor repeatability of migration time and peak area. In addition, chiral resolutions of basic drugs are commonly performed in low pH buffers. Therefore, longer analysis time due to suppression of electroosmotic flow (EOF) is another dilemma. In this work the improvement effect of polybrene (PB), a cationic polymer, on chiral separation of a model basic drug, amlodipine (AML), was investigated. PB both as a semi-permanent coating agent and as an additive in the running buffer was utilized. Better results were obtained with PB as a buffer additive. Compare to untreated bare silica without using PB in running buffer, addition of 0.0005% PB buffer decreased analysis time downed to 3 folds; efficiency improved up to 5 folds; limit of detection (LOD) and limit of quantification (LOQ) downed to 8 folds and within-day migration time and peak area repeatabilities, in terms of relative standard deviations (RSD) downed to 5 and 20 folds, respectively.
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Affiliation(s)
- Majid Zandkarimi
- School of Pharmacy, Zabol University of Medical Sciences, Zabol, Iran.
| | - Alireza Shafaati
- School of Pharmacy, Shaheed Beheshti University of Medical Sciences, Tehran, Iran. ,Corresponding author: E-mail:
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