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Shigeru Terabe - One of the best experts on this subject based on the ideXlab platform.

  • capillary separation micellar Electrokinetic Chromatography
    Reviews in Analytical Chemistry, 2009
    Co-Authors: Shigeru Terabe
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC), a separation mode of capillary electrophoresis (CE), has enabled the separation of electrically neutral analytes. MEKC can be performed by adding an ionic micelle to the running solution of CE without modifying the instrument. Its separation principle is based on the differential migration of the ionic micelles and the bulk running buffer under electrophoresis conditions and on the interaction between the analyte and the micelle. Hence, MEKC's separation principle is similar to that of Chromatography. MEKC is a useful technique particularly for the separation of small molecules, both neutral and charged, and yields high-efficiency separation in a short time with minimum amounts of sample and reagents. To improve the concentration sensitivity of detection, several on-line sample preconcentration techniques such as sweeping have been developed.

  • on line sample preconcentration techniques in micellar Electrokinetic Chromatography
    Journal of Pharmaceutical and Biomedical Analysis, 2003
    Co-Authors: Shigeru Terabe
    Abstract:

    This review provides an overview as well as a practical understanding of on-line sample concentration techniques in micellar Electrokinetic Chromatography (MEKC). MEKC as well as other capillary electrophoretic modes suffer from low concentration sensitivity due to minute sample volume and limited optical pathlength for on-capillary photometric detection. Two on-line sample preconcentration techniques, sample stacking and sweeping are known to be effective techniques for enhancement of the concentration sensitivity in MEKC. Sample stacking occurs as ions cross a boundary that separates regions of the high electric field sample zone and the low electric field background solution zone. The difference in migration velocity of pseudostationary phases within the two zones is the key to achieving the focusing effect. Sweeping is defined as the picking and accumulating of analytes by the pseudostationary phase that penetrates the sample zone devoid of pseudostationary phase. In this review, several examples of the sample stacking and sweeping under different experimental conditions are given, besides many references to applications.

  • anion selective exhaustive injection sweep micellar Electrokinetic Chromatography
    Journal of Chromatography A, 2001
    Co-Authors: Koji Otsuka, Shigeru Terabe
    Abstract:

    Abstract A selective on-line sample concentration technique of anion selective exhaustive injection (ASEI)-sweep–micellar Electrokinetic Chromatography (MEKC) was evaluated using a cationic surfactant. To suppress the electroosmotic flow, a polyacrylamide-coated capillary was introduced. Some aromatic carboxylic acids, dansyl amino acids, and naphthalenedisulfonic acids were used as test analytes. About 1000- to 6000-fold increases in detection sensitivity were obtained in terms of peak heights by ASEI-sweep–MEKC.

  • sweeping on a microchip concentration profiles of the focused zone in micellar Electrokinetic Chromatography
    Electrophoresis, 2001
    Co-Authors: Yoichi Sera, Norio Matsubara, Koji Otsuka, Shigeru Terabe
    Abstract:

    On-line sample concentration by sweeping was investigated in microchip micellar Electrokinetic Chromatography (MEKC), By changing the distance between the injection cross and the detection points, the profile of the concentration process and the diffusion process in sweeping was elucidated. Rhodamine B injected for 4 s was best concentrated by sweeping at 9.4 mm from the injection cross and the enhancement factor was 450. At the longer distance from this point the peak of Rhodamine B was broadened and diluted by diffusion. The diffusion constant of Rhodamine B calculated from the experiment was 5.7×10–6 cm2s–1. The mixture of rhodamine B, sulforhodamine B, and cresyl fast violet was concentrated by sweeping and separated by MEKC at the same time.

  • enantiomer separation of drugs by micellar Electrokinetic Chromatography using chiral surfactants
    Journal of Chromatography A, 2000
    Co-Authors: Koji Otsuka, Shigeru Terabe
    Abstract:

    Abstract A review surveying enantiomer separations by micellar Electrokinetic Chromatography (MEKC) using chiral surfactants is described. MEKC is one of the most popular techniques in capillary electrophoresis, where neutral compounds can be analyzed as well as charged ones, and the use of chiral micelles enable one to achieve the enantioseparation. The chiral MEKC systems are briefly reviewed according to the types of chiral surfactants along with typical applications. As chiral micelles or pseudostationary phases in MEKC, various natural and synthetic chiral surfactants are used, including several low-molecular-mass surfactants and polymerized surfactants or high-molecular-mass surfactants. Cyclodextrin modified MEKC using chiral micelles is also considered.

Hw Liu - One of the best experts on this subject based on the ideXlab platform.

  • Separation of biphenyl nitrile compounds by microemulsion Electrokinetic Chromatography with mixed surfactants
    中国化学快报英文版, 2004
    Co-Authors: Sx Gong, Bo T, Huang L, Hw Liu
    Abstract:

    A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion Electrokinetic Chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar Electrokinetic Chromatography (MEKC) method.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000223852800017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)1ARTICLE91063-10661

  • Separation and determination of biphenyl nitrile compounds by microemulsion Electrokinetic Chromatography with mixed surfactants
    electrophoresis, 2004
    Co-Authors: Sx Gong, Bo T, Huang L, Hw Liu
    Abstract:

    A mixture of six biphenyl nitrile compounds and three related substances with high hydrophobicity and similar structures was successfully separated by microemulsion Electrokinetic Chromatography (MEEKC) within 30 min. The microemulsion system contained 100 mm sodium dodecyl sulfate (SIDS), 80 mm sodium cholate (SC), 0.81% v/v heptane, 7.5% v/v n-butanol, 10% v/v acetonitrile, and 10 mm borate. The addition of SC, organic modifiers, sample preparation, and temperature all showed remarkable effects on the separation. The capacity factor (k) was calculated by using dodecyl benzene as the marker for microemulsion, and the calculated partition coefficient log P-o/w of the solutes was in the range of 3.35-7.38. The log k values matched well with the log P-o/w with a correlation coefficient of 0.96. In addition, the linear correlation coefficients of each compound between peak area and concentration were from 0.996 to 0.998 with the repeatability RSD value < 1.2% for migration time and < 4.8% for peak area, and the highest theoretic plate number was > 586 000. MEEKC was compared with micellar Electrokinetic Chromatography (MEKC) indicating that the former method is more suitable for this separation and can be used for the quality control of biphenyl nitrile compounds in the synthesis of liquid crystals.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000221168700017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Biochemical Research MethodsChemistry, AnalyticalSCI(E)PubMed27ARTICLE7-81058-10642

  • Comparison of micellar Electrokinetic Chromatography and microemulsion Electrokinetic Chromatography for separation of pharmacologically active xanthones from Securidaca inappendiculata
    journal of separation science, 2003
    Co-Authors: Bo T, Xd Yang, Hw Liu
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC) and microemulsion Electrokinetic Chromatography (MEEKC) have been investigated for the separation of nine xanthones from Securidaca inappendiculata, based on the systematic optimization of such parameters as pH, concentration of borate buffer, and sodium dodecyl sulfate (SDS) concentration. The study indicated that, in MEKC, although the addition of modifiers including organic solvents and cyclodextrins (CDs) could greatly affect the separation selectivity of xanthones, the baseline separation for nine xanthones could not be completed. As a special variant of Electrokinetic Chromatography (EKC), MEEKC successfully achieved the baseline separation of nine xanthones with satisfactory repeatability. Compared with MEKC, MEEKC showed better separation selectivity and higher separation efficiency.Chemistry, AnalyticalSCI(E)EI0ARTICLE1-2133-1362

  • Optimized separation of nine xanthones by microemulsion Electrokinetic Chromatography
    中国化学快报英文版, 2002
    Co-Authors: Bo T, Hw Liu
    Abstract:

    A microemulsion Electrokinetic Chromatography method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, composition of microemulsion, addition of cyclodextrins, applied voltage and column temperature. Baseline separation was successfully achieved for the nine xanthones, which was also compared with that by micellar Electrokinetic Chromatography.Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)1ARTICLE9877-8801

  • Optimized separation of pharmacologically active xanthones from Securidaca inappendiculata by micellar Electrokinetic Chromatography and microemulsion Electrokinetic Chromatography
    analytica chimica acta, 2002
    Co-Authors: Bo T, Xd Yang, Liu F, Lz Xiu, Hw Liu
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC) has been used for the separation of nine xanthones from Securidaca inappendiculata by using sodium dodecyl sulfate (SDS) micellar system, and the effects of different buffer modifiers including sodium cholate (SC), organic solvent and cyclodextrins (CDs) on the separation selectivity have been extensively studied, based on the systematically optimization of such parameters as pH, concentration of running buffer and SDS concentration. The results indicated that the additions of modifiers could greatly affect the separation selectivity of xanthones, and the migration order of those xanthones depends on their structures and solute-micelle-modifier interactions. As a special variant of Electrokinetic Chromatography, microemulsion Electrokinetic Chromatography (MEEKC) has also been utilized for this separation for the comparison with MEKC, showing that MEEKC has better selectivity. (C) 2002 Elsevier Science B.V. All rights reserved.Chemistry, AnalyticalSCI(E)0ARTICLE1-237-4847

Bo T - One of the best experts on this subject based on the ideXlab platform.

  • Separation of biphenyl nitrile compounds by microemulsion Electrokinetic Chromatography with mixed surfactants
    中国化学快报英文版, 2004
    Co-Authors: Sx Gong, Bo T, Huang L, Hw Liu
    Abstract:

    A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion Electrokinetic Chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar Electrokinetic Chromatography (MEKC) method.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000223852800017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)1ARTICLE91063-10661

  • Separation and determination of biphenyl nitrile compounds by microemulsion Electrokinetic Chromatography with mixed surfactants
    electrophoresis, 2004
    Co-Authors: Sx Gong, Bo T, Huang L, Hw Liu
    Abstract:

    A mixture of six biphenyl nitrile compounds and three related substances with high hydrophobicity and similar structures was successfully separated by microemulsion Electrokinetic Chromatography (MEEKC) within 30 min. The microemulsion system contained 100 mm sodium dodecyl sulfate (SIDS), 80 mm sodium cholate (SC), 0.81% v/v heptane, 7.5% v/v n-butanol, 10% v/v acetonitrile, and 10 mm borate. The addition of SC, organic modifiers, sample preparation, and temperature all showed remarkable effects on the separation. The capacity factor (k) was calculated by using dodecyl benzene as the marker for microemulsion, and the calculated partition coefficient log P-o/w of the solutes was in the range of 3.35-7.38. The log k values matched well with the log P-o/w with a correlation coefficient of 0.96. In addition, the linear correlation coefficients of each compound between peak area and concentration were from 0.996 to 0.998 with the repeatability RSD value < 1.2% for migration time and < 4.8% for peak area, and the highest theoretic plate number was > 586 000. MEEKC was compared with micellar Electrokinetic Chromatography (MEKC) indicating that the former method is more suitable for this separation and can be used for the quality control of biphenyl nitrile compounds in the synthesis of liquid crystals.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000221168700017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Biochemical Research MethodsChemistry, AnalyticalSCI(E)PubMed27ARTICLE7-81058-10642

  • Comparison of micellar Electrokinetic Chromatography and microemulsion Electrokinetic Chromatography for separation of pharmacologically active xanthones from Securidaca inappendiculata
    journal of separation science, 2003
    Co-Authors: Bo T, Xd Yang, Hw Liu
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC) and microemulsion Electrokinetic Chromatography (MEEKC) have been investigated for the separation of nine xanthones from Securidaca inappendiculata, based on the systematic optimization of such parameters as pH, concentration of borate buffer, and sodium dodecyl sulfate (SDS) concentration. The study indicated that, in MEKC, although the addition of modifiers including organic solvents and cyclodextrins (CDs) could greatly affect the separation selectivity of xanthones, the baseline separation for nine xanthones could not be completed. As a special variant of Electrokinetic Chromatography (EKC), MEEKC successfully achieved the baseline separation of nine xanthones with satisfactory repeatability. Compared with MEKC, MEEKC showed better separation selectivity and higher separation efficiency.Chemistry, AnalyticalSCI(E)EI0ARTICLE1-2133-1362

  • Optimized separation of nine xanthones by microemulsion Electrokinetic Chromatography
    中国化学快报英文版, 2002
    Co-Authors: Bo T, Hw Liu
    Abstract:

    A microemulsion Electrokinetic Chromatography method has been firstly used for the separation of the therapeutically important xanthones from Securidaca inappendiculata. The separation of the nine xanthones was systematically optimized with respect to pH, composition of microemulsion, addition of cyclodextrins, applied voltage and column temperature. Baseline separation was successfully achieved for the nine xanthones, which was also compared with that by micellar Electrokinetic Chromatography.Chemistry, MultidisciplinarySCI(E)中国科技核心期刊(ISTIC)1ARTICLE9877-8801

  • Optimized separation of pharmacologically active xanthones from Securidaca inappendiculata by micellar Electrokinetic Chromatography and microemulsion Electrokinetic Chromatography
    analytica chimica acta, 2002
    Co-Authors: Bo T, Xd Yang, Liu F, Lz Xiu, Hw Liu
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC) has been used for the separation of nine xanthones from Securidaca inappendiculata by using sodium dodecyl sulfate (SDS) micellar system, and the effects of different buffer modifiers including sodium cholate (SC), organic solvent and cyclodextrins (CDs) on the separation selectivity have been extensively studied, based on the systematically optimization of such parameters as pH, concentration of running buffer and SDS concentration. The results indicated that the additions of modifiers could greatly affect the separation selectivity of xanthones, and the migration order of those xanthones depends on their structures and solute-micelle-modifier interactions. As a special variant of Electrokinetic Chromatography, microemulsion Electrokinetic Chromatography (MEEKC) has also been utilized for this separation for the comparison with MEKC, showing that MEEKC has better selectivity. (C) 2002 Elsevier Science B.V. All rights reserved.Chemistry, AnalyticalSCI(E)0ARTICLE1-237-4847

Steven A Soper - One of the best experts on this subject based on the ideXlab platform.

  • ultra fast two dimensional microchip electrophoresis using sds μ cge and microemulsion Electrokinetic Chromatography for protein separations
    Analytical and Bioanalytical Chemistry, 2010
    Co-Authors: John K Osiri, Hamed Shadpour, Steven A Soper
    Abstract:

    A poly(methyl methacrylate) microfluidic chip was used to perform a two-dimensional (2-D) separation of a complex protein mixture in short development times. The separation was performed by combining sodium dodecyl sulfate micro-capillary gel electrophoresis (SDS micro-CGE) with microemulsion Electrokinetic Chromatography (micro-MEEKC), which were used for the first and second dimensions, respectively. Fluorescently labeled Escherichia coli cytosolic proteins were profiled by this 2-D approach with the results compared to a similar 2-D separation using SDS micro-CGE x micro-MEKC (micelle Electrokinetic Chromatography). The relatively short column lengths (effective length = 10 mm) for both dimensions were used to achieve separations requiring only 220 s of development time. High spot production rates (131 +/- 11 spots min(-1)) and reasonable peak capacities (481 +/- 18) were generated despite the fact that short columns were used. In addition, the use of mu-MEEKC in the second dimension was found to produce higher peak capacities compared to micro-MEKC (481 +/- 18 for micro-MEEKC and 332 +/- 17 for micro-MEKC) due to the higher plate numbers associated with micro-MEEKC.

Koji Otsuka - One of the best experts on this subject based on the ideXlab platform.

  • anion selective exhaustive injection sweep micellar Electrokinetic Chromatography
    Journal of Chromatography A, 2001
    Co-Authors: Koji Otsuka, Shigeru Terabe
    Abstract:

    Abstract A selective on-line sample concentration technique of anion selective exhaustive injection (ASEI)-sweep–micellar Electrokinetic Chromatography (MEKC) was evaluated using a cationic surfactant. To suppress the electroosmotic flow, a polyacrylamide-coated capillary was introduced. Some aromatic carboxylic acids, dansyl amino acids, and naphthalenedisulfonic acids were used as test analytes. About 1000- to 6000-fold increases in detection sensitivity were obtained in terms of peak heights by ASEI-sweep–MEKC.

  • sweeping on a microchip concentration profiles of the focused zone in micellar Electrokinetic Chromatography
    Electrophoresis, 2001
    Co-Authors: Yoichi Sera, Norio Matsubara, Koji Otsuka, Shigeru Terabe
    Abstract:

    On-line sample concentration by sweeping was investigated in microchip micellar Electrokinetic Chromatography (MEKC), By changing the distance between the injection cross and the detection points, the profile of the concentration process and the diffusion process in sweeping was elucidated. Rhodamine B injected for 4 s was best concentrated by sweeping at 9.4 mm from the injection cross and the enhancement factor was 450. At the longer distance from this point the peak of Rhodamine B was broadened and diluted by diffusion. The diffusion constant of Rhodamine B calculated from the experiment was 5.7×10–6 cm2s–1. The mixture of rhodamine B, sulforhodamine B, and cresyl fast violet was concentrated by sweeping and separated by MEKC at the same time.

  • enantiomer separation of drugs by micellar Electrokinetic Chromatography using chiral surfactants
    Journal of Chromatography A, 2000
    Co-Authors: Koji Otsuka, Shigeru Terabe
    Abstract:

    Abstract A review surveying enantiomer separations by micellar Electrokinetic Chromatography (MEKC) using chiral surfactants is described. MEKC is one of the most popular techniques in capillary electrophoresis, where neutral compounds can be analyzed as well as charged ones, and the use of chiral micelles enable one to achieve the enantioseparation. The chiral MEKC systems are briefly reviewed according to the types of chiral surfactants along with typical applications. As chiral micelles or pseudostationary phases in MEKC, various natural and synthetic chiral surfactants are used, including several low-molecular-mass surfactants and polymerized surfactants or high-molecular-mass surfactants. Cyclodextrin modified MEKC using chiral micelles is also considered.

  • micellar Electrokinetic Chromatography
    Bulletin of the Chemical Society of Japan, 1998
    Co-Authors: Koji Otsuka, Shigeru Terabe
    Abstract:

    A review of the research on micellar Electrokinetic Chromatography (MEKC), carried out mainly in our laboratory, is described from the viewpoints of (1) fundamental characteristics of MEKC, such as the separation principle, chromatographic parameters, selectivity and resolution, thermodynamic parameters, retention index, and band broadening; (2) selectivity manipulation, including effects of surfactants, temperature, pH, and various additives; (3) on-line coupling of MEKC with mass spectrometry; (4) applications, such as the separation of closely related compounds and enantiomer separations; and (5) on-line neutral sample concentration techniques.

  • Measurement of thermodynamic quantities of micellar solubilization by micellar Electrokinetic Chromatography with sodium dodecyl sulfate
    Journal of Microcolumn Separations, 1993
    Co-Authors: Shigeru Terabe, Yasushi Ishihama, Takehisa Katsura, Yukihirao Okada, Koji Otsuka
    Abstract:

    Micellar Electrokinetic Chromatography (MEKC) allows the calculation of distribution coefficients between a micelle and the surrounding aqueous phase from the measurement of the migration time, provided the critical micelle concentration (CMC) and the phase ratio are known. Thermodynamic quantities such as enthalpy and entropy changes of micellar solubilization were calculated from the temperature dependence of the distribution coefficients. Sodium dodecyl sulfate (SDS) was employed to prepare a micellar solution and its CMCs and partial specific volumes at different temperatures were measured. The relationship between the molecular structures of solutaes and the resulting thermodynamic quantities was investigated. The temperature inside the capillary was calculated from the temperature dependence of the distribution coefficient.