1
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Reversed-phase chromatographic separation and downstream precipitation of lupane- and oleanane-type triterpenoids: Experiments and modeling based on the method of moments. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.118208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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2
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Zhang Y, Zhong H, Zhou S, Han H, Zhang M, Qiu H. A docosyl-terminated polyamine amphiphile-bonded stationary phase for multimodal separations in liquid chromatography. J Chromatogr A 2021; 1642:462045. [PMID: 33735643 DOI: 10.1016/j.chroma.2021.462045] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/02/2021] [Accepted: 03/03/2021] [Indexed: 12/23/2022]
Abstract
A convenient synthetic approach to a linear alkyl-polyamine amphiphilic chromatographic selector was proposed. Successive immobilization of the amphiphile onto silica gel afforded a multimodal stationary phase for high-performance liquid chromatography (HPLC). The as-prepared silica material was studied comparatively with a conventional octadecyl (C18) and an amide-embedded C18 stationary phase. The new uniform docosyl-triamine tandem was featured by an enhanced shape selectivity towards geometric isomers, and a low silanol activity towards alkaline solutes. The presence of multiple amino groups rendered the new adsorbent operable in different modes, such as hydrophilic interaction and ion-exchange modes. The satisfactory performance of the said stationary phase in separating different classes of analytes, including polycyclic aromatic hydrocarbons, flavonoids, tricyclic antidepressants, calcium channel blockers, aromatic acids, inorganic anions, nucleosides and estrogens, revealed its great potential and high adaptability for multipurpose LC utility.
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Affiliation(s)
- Yujie Zhang
- School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an223000, China; Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Hui Zhong
- School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an223000, China
| | - Shouyong Zhou
- School of Chemistry and Chemical Engineering, Huaiyin Normal University, Huai'an223000, China
| | - Haifeng Han
- Jiangsu Hanbon Science & Technology Co. Ltd., Huai'an223000, China; Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China
| | - Mingliang Zhang
- Jiangsu Hanbon Science & Technology Co. Ltd., Huai'an223000, China; Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China.
| | - Hongdeng Qiu
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou730000, China; College of Chemistry, Zhengzhou University, Zhengzhou450001, China
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3
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Enhanced separation of bioactive triterpenic acids with a triacontylsilyl silica gel adsorbent: From impulse and breakthrough experiments to the design of a simulated moving bed unit. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116991] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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4
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Saha S, Walia S, Sharma K, Banerjee K. Suitability of stationary phase for LC analysis of biomolecules. Crit Rev Food Sci Nutr 2019; 60:2856-2873. [PMID: 31621391 DOI: 10.1080/10408398.2019.1665494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Biologically active compounds such as carotenoids/isoprenoids, vitamins, steroids, saponins, sugars, long chain fatty acids, and amino acids play a very important role in coordinating functions in living organisms. Determination of those substances is indispensable in advanced biological sciences. Engineered stationary phase in LC for the analysis of biomolecules has become easier with the development of chromatographic science. In general, C18 column is being used for routine analysis but specific columns are being used for specific molecule. Monolithic columns are found to have higher efficiency than normal column. Among recent introduction, triacontyl stationary phases, designed for the separation of carotenoid isomers, are widely used for the estimation of carotenoids. In comparison to conventional C18 phases, C30 phases exhibited superior shape selectivity for the separation of isomers of carotenoids. It is also found useful for better elution and analysis of tocopherols, vitamin K, sterols, and fatty acids. Vitamin K, E, and their isomers are also successfully resoluted and analyzed by using C30 column. Amino bonded phase column is specifically used for better elution of sugars, whereas phenyl columns are suitable for the separation and analysis of curcuminoids and taxol. Like triacontyl stationary phase, pentafluorophenyl columns are also used for the separation and analysis of carotenoids. Similarly, HILIC column are best suited for sugar analysis. All the stationary phases are made possible to resolute and analyze the target biomolecules better, which are the future of liquid chromatography. The present article focuses on the differential interaction between stationary phase and target biomolecules. The applicability of these stationary phases are reported in different matrices.
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Affiliation(s)
- Supradip Saha
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Suresh Walia
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Khushbu Sharma
- Division of Agricultural Chemicals, ICAR-Indian Agricultural Research Institute, New Delhi, India
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5
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Mallik AK, Qiu H, Takafuji M, Ihara H. High molecular-shape-selective stationary phases for reversed-phase liquid chromatography: A review. Trends Analyt Chem 2018. [DOI: 10.1016/j.trac.2018.09.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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6
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Čolović J, Rmandić M, Malenović A. Characterization of bonded stationary phase performance as a function of qualitative and quantitative chromatographic factors in chaotropic chromatography with risperidone and its impurities as model substances. Anal Bioanal Chem 2018; 410:4855-4866. [PMID: 29770836 DOI: 10.1007/s00216-018-1122-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 04/17/2018] [Accepted: 05/01/2018] [Indexed: 11/30/2022]
Abstract
Numerous stationary phases have been developed with the aim to provide desired performances during chromatographic analysis of the basic solutes in their protonated form. In this work, the procedure for the characterization of bonded stationary phase performance, when both qualitative and quantitative chromatographic factors were varied in chaotropic chromatography, was proposed. Risperidone and its three impurities were selected as model substances, while acetonitrile content in the mobile phase (20-30%), the pH of the aqueous phase (3.00-5.00), the content of chaotropic agents in the aqueous phase (10-100 mM), type of chaotropic agent (NaClO4, CF3COONa), and stationary phase type (Zorbax Eclipse XDB, Zorbax Extend) were studied as chromatographic factors. The proposed procedure implies the combination of D-optimal experimental design, indirect modeling, and polynomial-modified Gaussian model, while grid point search method was selected for the final choice of the experimental conditions which lead to the best possible stationary phase performance for basic solutes. Good agreement between experimentally obtained chromatogram and simulated chromatogram for chosen experimental conditions (25% acetonitrile, 75 mM of NaClO4, pH 4.00 on Zorbax Eclipse XDB column) confirmed the applicability of the proposed procedure. The additional point was selected for the verification of proposed procedure ability to distinguish changes in solutes' elution order. Simulated chromatogram for 21.5% acetonitrile, 85 mM of NaClO4, pH 5.00 on Zorbax Eclipse XDB column was in line with experimental data. Furthermore, the values of left and right peak half-widths obtained from indirect modeling were used in order to evaluate performances of differently modified stationary phases applying a half-width plots approach. The results from half-width plot approach as well as from the proposed procedure indicate higher efficiency and better separation performance of the stationary phase extra densely bonded and double end-capped with trimethylsilyl group than the stationary phase with the combination of end-capping and bidentate silane bonding for chromatographic analysis of basic solutes in RP-HPLC systems with chaotropic agents. Graphical abstract ᅟ.
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Affiliation(s)
- Jelena Čolović
- Faculty of Pharmacy, Department of Drug Analysis, University of Belgrade, Vojvode Stepe 450, Belgrade, Serbia
| | - Milena Rmandić
- Faculty of Pharmacy, Department of Drug Analysis, University of Belgrade, Vojvode Stepe 450, Belgrade, Serbia
| | - Anđelija Malenović
- Faculty of Pharmacy, Department of Drug Analysis, University of Belgrade, Vojvode Stepe 450, Belgrade, Serbia.
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7
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Zhang Y, Li Q, Dai B, Zhou S, Zhang M, Han H, Qiu H. A versatile polar-embedded polyphenyl phase for multimodal separation in liquid chromatography. J Chromatogr A 2018; 1553:81-89. [DOI: 10.1016/j.chroma.2018.04.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 04/07/2018] [Accepted: 04/10/2018] [Indexed: 10/17/2022]
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8
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ZHANG X, LI H, ZHANG L, KONG F, FAN D, WANG W. Porous Organic Cage Embedded C18 Amide Silica Stationary Phase for High Performance Liquid Chromatography. ANAL SCI 2018; 34:445-451. [DOI: 10.2116/analsci.17p473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Xuemeng ZHANG
- School of Chemistry and Chemical Engineering, Jiangsu University
| | - Hengye LI
- School of Chemistry and Chemical Engineering, Yancheng Institute of Technology
| | - Lin ZHANG
- Yancheng Entry-Exit Inspection and Quarantine Bureau
| | - Fenying KONG
- School of Chemistry and Chemical Engineering, Yancheng Institute of Technology
| | - Dahe FAN
- School of Chemistry and Chemical Engineering, Yancheng Institute of Technology
| | - Wei WANG
- School of Chemistry and Chemical Engineering, Yancheng Institute of Technology
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9
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Fanali C, D'Orazio G, Fanali S, Gentili A. Advanced analytical techniques for fat-soluble vitamin analysis. Trends Analyt Chem 2017. [DOI: 10.1016/j.trac.2016.12.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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10
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Zhang M, Mai W, Zhao L, Guo Y, Qiu H. A polar-embedded C30 stationary phase: Preparation and evaluation. J Chromatogr A 2015; 1388:133-40. [DOI: 10.1016/j.chroma.2015.02.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/06/2015] [Accepted: 02/07/2015] [Indexed: 11/26/2022]
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11
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Zhang M, Qiu H. Progress in stationary phases modified with carbonaceous nanomaterials for high-performance liquid chromatography. Trends Analyt Chem 2015. [DOI: 10.1016/j.trac.2014.10.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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12
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Nimalaratne C, Sun C, Wu J, Curtis JM, Schieber A. Quantification of selected fat soluble vitamins and carotenoids in infant formula and dietary supplements using fast liquid chromatography coupled with tandem mass spectrometry. Food Res Int 2014. [DOI: 10.1016/j.foodres.2014.08.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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13
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Preparation and chromatographic evaluation of new branch-type diamide-embedded octadecyl stationary phase with enhanced shape selectivity. Anal Chim Acta 2014; 833:48-55. [DOI: 10.1016/j.aca.2014.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 04/29/2014] [Accepted: 05/02/2014] [Indexed: 11/19/2022]
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14
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Ramirez CE, Wang C, Gardinali PR. Fully automated trace level determination of parent and alkylated PAHs in environmental waters by online SPE-LC-APPI-MS/MS. Anal Bioanal Chem 2013; 406:329-44. [DOI: 10.1007/s00216-013-7436-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 10/09/2013] [Accepted: 10/14/2013] [Indexed: 11/29/2022]
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15
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Effect of mobile phase on resolution of the isomers and homologues of tocopherols on a triacontyl stationary phase. Anal Bioanal Chem 2013; 405:9285-95. [DOI: 10.1007/s00216-013-7336-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 08/14/2013] [Accepted: 08/31/2013] [Indexed: 10/26/2022]
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16
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Franke AA, Morrison CM, Custer LJ, Li X, Lai JF. Simultaneous analysis of circulating 25-hydroxy-vitamin D3, 25-hydroxy-vitamin D2, retinol, tocopherols, carotenoids, and oxidized and reduced coenzyme Q10 by high performance liquid chromatography with photo diode-array detection using C18 and C30 columns alone or in combination. J Chromatogr A 2013; 1301:1-9. [PMID: 23827466 PMCID: PMC4128684 DOI: 10.1016/j.chroma.2013.05.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/10/2013] [Accepted: 05/13/2013] [Indexed: 11/23/2022]
Abstract
Circulating lipid-phase micronutrients (LPM) such as 25-hydroxylated D vitamers, retinol, tocopherols, carotenoids including their isomers, and coenzyme Q10 play important roles in health maintenance and disease prevention and can serve as useful biomarkers. We developed fast, affordable, and accurate HPLC assays that simultaneously measured all above LPM in a single run using UV/VIS detection at 265nm, 295nm, and 480nm with (1) a C18 column alone; (2) a C30 column alone; or (3) each of these columns connected in series. The C18 column alone could separate all major LPM of interest in less than 17min but insufficiently resolved the lycopene isomers, the 25-hydroxylated D vitamers, lutein from zeaxanthin and β- from γ-tocopherol. The C30 column alone separated all LPM of interest including many isomeric analytes but failed to resolve the Q10 compounds, which co-eluted with carotenoids. Connecting the C18 and C30 columns in series with a detector after the C30 column and a pressure resistant detector between the columns resulted in ideal resolution and accurate quantitation of all LPM of interest but required software capable of processing the acquired data from both detectors. Connecting the C18 and C30 columns in series with exclusively one detector after the C30 column resulted in carotenoid-Q10 interferences, however, this was remedied by heart-cutting 2D-LC with a 6-port valve between the columns, which resolved all analytes in 42min. Faster run times led to some analytes not being resolved. Many variations of these methods are possible to meet the needs of individual requirements while minimizing sample material and turn-around-times.
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Affiliation(s)
- Adrian A Franke
- University of Hawai'i Cancer Center, Honolulu, HI 96813, USA.
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17
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Ashu-Arrah BA, Glennon JD, Albert K. Synthesis, characterisation and chromatographic evaluation of pentafluorophenyl and phenyl bonded silica phases prepared using supercritical carbon dioxide as a reaction solvent. J Chromatogr A 2013; 1273:34-43. [DOI: 10.1016/j.chroma.2012.11.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 11/15/2012] [Accepted: 11/16/2012] [Indexed: 10/27/2022]
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18
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Extension of the carotenoid test to superficially porous C18 bonded phases, aromatic ligand types and new classical C18 bonded phases. J Chromatogr A 2012; 1266:34-42. [DOI: 10.1016/j.chroma.2012.09.068] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/06/2012] [Accepted: 09/10/2012] [Indexed: 11/18/2022]
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19
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Qiu H, Mallik AK, Takafuji M, Liu X, Jiang S, Ihara H. A new imidazolium-embedded C18 stationary phase with enhanced performance in reversed-phase liquid chromatography. Anal Chim Acta 2012; 738:95-101. [DOI: 10.1016/j.aca.2012.06.018] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/09/2012] [Accepted: 06/10/2012] [Indexed: 11/30/2022]
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20
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Rimmer CA, Putzbach K, Sharpless KE, Sander LC, Yen JH. Preparation and certification of standard reference material 3278 tocopherols in edible oils. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:6794-6798. [PMID: 22686411 DOI: 10.1021/jf2051619] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Standard Reference Material (SRM) 3278 Tocopherols in Edible Oils has been issued for use as a quality assurance tool in the measurement of tocopherols. Like other natural-matrix SRMs, this material can be used in method validation or in assignment of tocopherol values to in-house quality control materials. Because most edible oils contain one predominant tocopherol isoform, the SRM is a blend of sunflower, soy, canola, and safflower oils to provide roughly comparable chromatographic peak heights of the two main tocopherols, γ and α, with smaller amounts of δ and β. The four tocopherol isoforms were determined by three independent liquid chromatography methods with absorbance and fluorescence detection. Various chromatographic and detection modes are used for assignment of certified values because biases inherent to one method should not be present in the other, and the existence of bias can therefore be identified.
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Affiliation(s)
- Catherine A Rimmer
- Analytical Chemistry Division, National Institute of Standards and Technology , Gaithersburg, Maryland 20899-8392, United States
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21
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Rivera S, Canela-Garayoa R. Analytical tools for the analysis of carotenoids in diverse materials. J Chromatogr A 2012; 1224:1-10. [DOI: 10.1016/j.chroma.2011.12.025] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 11/30/2011] [Accepted: 12/04/2011] [Indexed: 11/16/2022]
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22
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Lesellier E. Extension of the C18 stationary phase knowledge by using the carotenoid test. J Sep Sci 2010; 33:3097-105. [DOI: 10.1002/jssc.201000239] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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23
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Mallik AK, Sawada T, Takafuji M, Ihara H. Novel Approach for the Separation of Shape-Constrained Isomers with Alternating Copolymer-Grafted Silica in Reversed-Phase Liquid Chromatography. Anal Chem 2010; 82:3320-8. [DOI: 10.1021/ac1001178] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Abul K. Mallik
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Tsuyoshi Sawada
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Makoto Takafuji
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Hirotaka Ihara
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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24
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Kühnle M, Friebolin V, Albert K, Rimmer CA, Lippa KA, Sander LC. Architecture and Dynamics of C18 Bonded Interphases with Small Molecule Spacers. Anal Chem 2009; 81:10136-42. [DOI: 10.1021/ac901911w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Moltó-Puigmartí C, Castellote AI, López-Sabater MC. Ultra-High-Pressure Liquid Chromatographic method for the analysis of tocopherols in human colostrum and milk. J Chromatogr A 2009; 1216:4388-94. [DOI: 10.1016/j.chroma.2009.02.088] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 02/20/2009] [Accepted: 02/27/2009] [Indexed: 10/21/2022]
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26
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Chen Y, Chen J, Jia L. Study of triacontyl-functionalized monolithic silica capillary column for reversed-phase capillary liquid chromatography. J Chromatogr A 2009; 1216:2597-600. [DOI: 10.1016/j.chroma.2009.01.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2008] [Revised: 01/09/2009] [Accepted: 01/16/2009] [Indexed: 11/27/2022]
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27
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Horak J, Lindner W. Contribution of sulfonyl–aromatic and sulfonic acid–aromatic interactions in novel sulfonyl/sulfonic acid-embedded reversed phase materials. J Chromatogr A 2008; 1191:141-56. [DOI: 10.1016/j.chroma.2007.12.059] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 12/19/2007] [Accepted: 12/21/2007] [Indexed: 11/24/2022]
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28
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Abstract
The properties of stationary phases and their characterization methods are reviewed. New and significant developments have occurred in the last few years, and new methods for stationary phase characterization have become available. The characterization methods are discussed, and the differences between the different methods are pointed out. In addition, method development approaches are reviewed, with special emphasis on recent developments that employ multiple parameters in parallel. Also, the renewed interest of temperature as a tool in method development is surveyed.
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Affiliation(s)
- Uwe D Neue
- Waters Corporation, Milford, MA 01757, USA.
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29
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Lippa KA, Sander LC. Identification of isolated cavity features within molecular dynamics simulated chromatographic surfaces. J Chromatogr A 2006; 1128:79-89. [PMID: 16846606 DOI: 10.1016/j.chroma.2006.06.043] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 06/06/2006] [Accepted: 06/13/2006] [Indexed: 10/24/2022]
Abstract
Highly ordered morphological features were characterized for molecular dynamics simulated alkyl-modified silica models that represent chromatographic materials with enhanced shape recognition capability. Deep cavities (8-10A wide) within the alkyl chains were identified for C18 polymeric models corresponding to shape-selective RPLC stationary phases. The all-trans conformational distal-end segments of these isolated cavities averaged over a 100 ps simulation time interval were observed to increase (up to 15 A) in models with an increase in both surface coverage and corresponding shape selectivity. Similar-structure cavities with significant alkyl chain ordered regions (>11A) were isolated from two independent C18 models (differing in bonding chemistry, density and temperature) that represent highly shape-selective materials. The size and depth of these ordered regions increased (up to 28 A) for the extended-length C30 alkyl phase models. These initial results offer a physical representation of alkyl-modified surfaces that may facilitate the identification of potential molecular features that may be involved in the shape-selective retentive processes, as well as illustrating the potential for such computational techniques to predict the molecular recognition capabilities of novel analyte-specific sorbents.
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Affiliation(s)
- Katrice A Lippa
- Analytical Chemistry Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899, USA.
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30
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Meyer C, Pascui O, Reichert D, Sander LC, Wise SA, Albert K. Conformational temperature dependence of a poly(ethylene-co-acrylic acid) stationary phase investigated by nuclear magnetic resonance spectroscopy and liquid chromatography. J Sep Sci 2006; 29:820-8. [PMID: 16830494 DOI: 10.1002/jssc.200500376] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A polymer-based RP sorbent was prepared by immobilizing a poly(ethylene-co-acrylic acid) copolymer with an acid mass fraction of 5% on silica by using a 3-glycidoxypropyl linkage. 13C cross-polarization/magic angle spinning NMR spectroscopy of the sorbent, either in the dry state or suspended in the mobile phase, showed an increase in mobility at elevated temperatures. Alkyl chain segments with gauche conformations were more mobile than chain segments with trans conformations. The strength of the 13C-1H dipolar couplings in the alkyl chains was measured using the constant time dipolar and chemical shift pulse sequence, revealing less molecular motion for the trans conformation. Non-linear van't Hoff plots were observed for separations of shape-constrained solutes (such as geometric beta-carotene isomers and polycyclic aromatic hydrocarbons). At higher temperatures, the retention behavior was similar to that of monomeric C18 sorbents, whereas at ambient and lower temperatures, enhanced shape-selective properties were exhibited similar to those of polymeric C30 sorbents.
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Affiliation(s)
- Christoph Meyer
- Institute of Organic Chemistry, University of Tuebingen, Tuebingen, Germany
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31
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Meyer C, Busche S, Welsch N, Wegmann J, Gauglitz G, Albert K. Contact-angle, ellipsometric, and spin-diffusion solid-state nuclear magnetic resonance spectroscopic investigations of copolymeric stationary phases immobilized on SiO2 surfaces. Anal Bioanal Chem 2005; 382:1465-71. [PMID: 16001236 DOI: 10.1007/s00216-005-3363-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 05/20/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
SiO2 surfaces-silica gel particles and silica wafers-were modified by covalently immobilizing three poly(ethylene-co-acrylic acid) copolymers, (-CH2CH2-)x[CH2CH/(CO2H)-]y, with different chain lengths and mass fractions of acrylic acid. 13C solid-state NMR spectroscopy on the modified silica gel particles revealed both mobile gauche and rigid trans aligned alkyl chains in the copolymers. For copolymers attached to silica wafers via a 3-aminopropyltriethoxysilane spacer molecule, ellipsometric measurements revealed a mean value of the layer thickness distribution of 6.5 and 4.3 nm, respectively, for the more acidic and the shorter copolymers with mobile alkyl chains mostly in the gauche conformation. For the longest and least acidic copolymer with more rigid trans ordered alkyl chains, however, a mean phase thickness of 10.6 nm was found. When this copolymer was immobilized via a 3-glycidoxypropyltrimethoxysilane spacer molecule we measured a mean layer thickness of 9.9 nm. A model of the surface morphology of this immobilization strategy was derived using spin-diffusion 13C NMR measurements on the corresponding modified silica. It was thereby proven that the trans and gauche-aligned alkyl chains occur in distinct domains of certain sizes on the silica surface. The surface polarity of all modified silica wafers was also investigated by measurement of contact-angle.
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Affiliation(s)
- Christoph Meyer
- Institute of Organic Chemistry, University of Tuebingen, Auf der Morgenstelle 18, 72076, Tuebingen, Germany.
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