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Karl Mechtler - One of the best experts on this subject based on the ideXlab platform.
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Anion Exchange chromatography of phosphopeptides weak Anion Exchange versus strong Anion Exchange and Anion Exchange chromatography versus electrostatic repulsion hydrophilic interaction chromatography
Analytical Chemistry, 2015Co-Authors: Andrew J Alpert, Otto Hudecz, Karl MechtlerAbstract:Most phosphoproteomics experiments rely on prefractionation of tryptic digests before online liquid chromatography-mass spectrometry. This study compares the potential and limitations of electrostatic repulsion–hydrophilic interaction chromatography (ERLIC) and Anion-Exchange chromatography (AEX). At a pH higher than 5, phosphopeptides have two negative charges per residue and are well-retained in AEX. However, peptides with one or two phosphate groups are not separated from peptides with multiple Asp or Glu residues, interfering with the identification of phosphopeptides. At a pH of 2, phosphate residues have just a single negative charge but Asp and Glu are uncharged. This facilitates the separation of phosphopeptides from unmodified acidic peptides. Singly phosphorylated peptides are retained weakly under these conditions, due to electrostatic repulsion, unless hydrophilic interaction is superimposed in the ERLIC mode. Weak Anion-Exchange (WAX) and strong Anion-Exchange (SAX) columns were compared, wit...
Andrew J Alpert - One of the best experts on this subject based on the ideXlab platform.
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Anion Exchange chromatography of phosphopeptides weak Anion Exchange versus strong Anion Exchange and Anion Exchange chromatography versus electrostatic repulsion hydrophilic interaction chromatography
Analytical Chemistry, 2015Co-Authors: Andrew J Alpert, Otto Hudecz, Karl MechtlerAbstract:Most phosphoproteomics experiments rely on prefractionation of tryptic digests before online liquid chromatography-mass spectrometry. This study compares the potential and limitations of electrostatic repulsion–hydrophilic interaction chromatography (ERLIC) and Anion-Exchange chromatography (AEX). At a pH higher than 5, phosphopeptides have two negative charges per residue and are well-retained in AEX. However, peptides with one or two phosphate groups are not separated from peptides with multiple Asp or Glu residues, interfering with the identification of phosphopeptides. At a pH of 2, phosphate residues have just a single negative charge but Asp and Glu are uncharged. This facilitates the separation of phosphopeptides from unmodified acidic peptides. Singly phosphorylated peptides are retained weakly under these conditions, due to electrostatic repulsion, unless hydrophilic interaction is superimposed in the ERLIC mode. Weak Anion-Exchange (WAX) and strong Anion-Exchange (SAX) columns were compared, wit...
Toshikatsu Sata - One of the best experts on this subject based on the ideXlab platform.
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studies on Anion Exchange membranes having permselectivity for specific Anions in electrodialysis effect of hydrophilicity of Anion Exchange membranes on permselectivity of Anions
Journal of Membrane Science, 2000Co-Authors: Toshikatsu SataAbstract:Abstract Recent studies on Anion Exchange membranes and electrodialysis methods to permeate specific Anions through the membranes are reviewed. The studies are classified: (1) to increase cross-linkage of the Anion Exchange membranes, (2) to form tight surface layers on the Anion Exchange membranes, (3) to decrease hydrophilicity of the Anion Exchange membranes or their surfaces by introducing specific Anion Exchange groups in the membranes, (4) to impregnate hydrophilic compounds in the Anion Exchange membranes to increase hydrophilicity of the membranes, (5) to control permselectivity of Anions by photoirradiation using membranes with a photoresponsive group and (6) to control permselectivity of Anions through thermally responsive Anion Exchange membranes with temperature. Permselectivity of specific Anions through the Anion Exchange membranes is governed mainly by the balance of hydration energy of Anions with hydrophilicity of the membranes, partially by hydrated ionic size of the Anions, except the membranes having an oppositely charged layer on the membrane surface.
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Studies on Anion Exchange membranes having permselectivity for specific Anions in electrodialysis — effect of hydrophilicity of Anion Exchange membranes on permselectivity of Anions
Journal of Membrane Science, 2000Co-Authors: Toshikatsu SataAbstract:Abstract Recent studies on Anion Exchange membranes and electrodialysis methods to permeate specific Anions through the membranes are reviewed. The studies are classified: (1) to increase cross-linkage of the Anion Exchange membranes, (2) to form tight surface layers on the Anion Exchange membranes, (3) to decrease hydrophilicity of the Anion Exchange membranes or their surfaces by introducing specific Anion Exchange groups in the membranes, (4) to impregnate hydrophilic compounds in the Anion Exchange membranes to increase hydrophilicity of the membranes, (5) to control permselectivity of Anions by photoirradiation using membranes with a photoresponsive group and (6) to control permselectivity of Anions through thermally responsive Anion Exchange membranes with temperature. Permselectivity of specific Anions through the Anion Exchange membranes is governed mainly by the balance of hydration energy of Anions with hydrophilicity of the membranes, partially by hydrated ionic size of the Anions, except the membranes having an oppositely charged layer on the membrane surface.
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Selectivity of Anion Exchange Resin Modified with Anionic Polyelectrolyte.
Analytical Sciences, 1997Co-Authors: Koji Matsusaki, Noriaki Hashimoto, Nobuhiro Kuroki, Toshikatsu SataAbstract:In order to change the ion-Exchange selectivity of Anion Exchange resin, especially to make the ion-Exchange of divalent Anions more difficult, the surface of gel-type Anion Exchange resin was modified by the adsorption of an Anionic polyelectrolyte: polycondensation product of sodium naphthalene sulfonate and formaldehyde. After the adsorption of the polymer, ion Exchange capacity decreased and the rate of ion Exchange reaction became slow, though ion Exchange equilibrium constants between two Anions did not change. Especially, the ion Exchange rate of divalent Anions was slower than that of the monovalent Anions. Because an Anionic polyelectrolyte layer was formed on the resin particle, the ion Exchange of Anions with Anion Exchange site was retarded by a sieving effect due to the layer. The divalent Anions became difficult to ion Exchange compared with the monovalent Anions due to the existence of the layer which was charged opposite to the charge of the ion Exchange groups. Using the modified Anion Exchange resin, separation of nitrate ions from sulfate ions was attempted.
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change of Anion Exchange membranes in an aqueous sodium hydroxide solution at high temperature
Journal of Membrane Science, 1996Co-Authors: Toshikatsu Sata, Makie Tsujimoto, Takanori Yamaguchi, Koji MatsusakiAbstract:Properties of commercial Anion Exchange membranes were examined after the membranes had been immersed in an aqueous sodium hydroxide solution, 3.0 to 9.0 N, of high temperature, up to 75°C. The Anion Exchange membranes used had N-methyl-pyridinium groups or benzyl trimethylammonium groups bonded to a styrene-based copolymer as Anion Exchange groups, with backing polymers. Alkali deterioration of the membranes was classified: decomposition of backing polymers (added inert polymer and backing fabric) and decomposition of Anion Exchange groups. N-Methyl-pyridinium groups were especially easy to decompose compared with benzyl trimethylammonium groups, and lost ion-Exchange ability. Benzyl trimethylammonium groups also lost ion-Exchange ability and changed partially in weakly basic Anion Exchange groups. The Anion Exchange membranes with various Anion Exchange groups, benzyl trimethylammonium groups, triethyl-, tri-n-propyl-, tri-n-butyl-, and 1-azonia-4-azabicyclo-[2,2,2]-octane (different hydrophobicity) were prepared from base membranes of chloromethylated polysulfone, and copolymer of chloromethylstyrene and divinylvenzene with polyethylene fabric and powder. Though the membrane based on polysulfone weakened mechanically by immersion the membrane in the alkali solution, polyethylene reinforced-membrane did not change mechanically. However, with increasing chain length of alkyl groups bonded to ammonium groups, loss of the Anion Exchange capacity was remarkable and 1-benzyl-azonia-4-azabicyclo-[2,2,2]-octane groups were also not stable. The most stable Anion Exchange groups among these were benzyl trimethylammonium groups.
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Anion Exchange membrane with viologen moiety as Anion Exchange groups and generation of photo-induced electrical potential from the membrane
Journal of Membrane Science, 1996Co-Authors: Toshikatsu SataAbstract:Abstract An Anion Exchange membrane with a viologen moiety was prepared by the reaction of a film of chloromethylated polysulfone and 4,4′-bipyridine. The Anion Exchange membrane showed a high electrical resistance and a high transport number of Anions due to the development of high crosslinking by the diamine. After the membrane had been swollen with ethylene glycol, photo-voltage and photo-current (82 mV, 410 nA at 200 kΩ load, 160 μm thick membrane) were generated from the membrane upon photo-irradiation.
R. Stevenson - One of the best experts on this subject based on the ideXlab platform.
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Anion-Exchange resins from allylammonium salts
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: A. L. Clingman, J. R. Parrish, R. StevensonAbstract:Anion-Exchange resins of high capacity have been obtained by the polymerisation of allyl-ammonium chlorides. The Exchange rates of different resins have been compared by the measurement of electrical conductivity.
Otto Hudecz - One of the best experts on this subject based on the ideXlab platform.
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Anion Exchange chromatography of phosphopeptides weak Anion Exchange versus strong Anion Exchange and Anion Exchange chromatography versus electrostatic repulsion hydrophilic interaction chromatography
Analytical Chemistry, 2015Co-Authors: Andrew J Alpert, Otto Hudecz, Karl MechtlerAbstract:Most phosphoproteomics experiments rely on prefractionation of tryptic digests before online liquid chromatography-mass spectrometry. This study compares the potential and limitations of electrostatic repulsion–hydrophilic interaction chromatography (ERLIC) and Anion-Exchange chromatography (AEX). At a pH higher than 5, phosphopeptides have two negative charges per residue and are well-retained in AEX. However, peptides with one or two phosphate groups are not separated from peptides with multiple Asp or Glu residues, interfering with the identification of phosphopeptides. At a pH of 2, phosphate residues have just a single negative charge but Asp and Glu are uncharged. This facilitates the separation of phosphopeptides from unmodified acidic peptides. Singly phosphorylated peptides are retained weakly under these conditions, due to electrostatic repulsion, unless hydrophilic interaction is superimposed in the ERLIC mode. Weak Anion-Exchange (WAX) and strong Anion-Exchange (SAX) columns were compared, wit...
