Maria Rowena N Monton

Keio University, Tokyo, Tokyo-to, Japan

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Publications (9)37.55 Total impact

  • Maria Rowena N Monton, Masaru Tomita, Tomoyoshi Soga, Yasushi Ishihama
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    ABSTRACT: An easy-to-implement capillary coating strategy based on polymer entrapment in the network of polymerized silicate is described. In this manner, cationic polymers are tightly fixed onto the inner wall of the capillary for electroosmotic flow control without necessitating complex surface modification chemistries. The resulting coated capillary exhibited good stability over a wide range of pH, good reproducibility, strong endurance in more than 300 electrophoretic runs, and tolerance of commonly employed organic solvent additives in CE. Applications in CE-MS analysis of biologically important anions as well as sample enrichment are shown. Additionally, it was used as a durable base for attachment of multiple layers of charged polymers on the wall, via electrostatic interaction with the preceding layer. Thus, two novel types of highly stable coated capillaries, one with anodic EOF and the other cathodic, were developed.
    Analytical Chemistry 11/2007; 79(20):7838-44. · 5.82 Impact Factor
  • Maria Rowena N Monton, Tomoyoshi Soga
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    ABSTRACT: Capillary electrophoresis (CE)-mass spectrometry (MS), as an analytical platform, has made significant contributions in advancing metabolomics research, if still limited up to this time. This review, covering reports published between 1998 and 2006, describes how CE-MS has been used thus far in this field, with the majority of the works dealing with targeted metabolite analyses and only a small fraction using it in the comprehensive context. It also discusses how some of the key features of CE-MS were exploited in selected metabolomic applications.
    Journal of Chromatography A 11/2007; 1168(1-2):237-46; discussion 236. · 4.61 Impact Factor
  • Koshi Imami, Maria Rowena N Monton, Yasushi Ishihama, Shigeru Terabe
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    ABSTRACT: We report an on-line sample preconcentration technique based on dynamic pH junction in capillary electrophoresis-mass spectrometry (CE-MS). For peptide analysis, the samples were dissolved in a solution with higher pH than the background solution (BGS), and were injected into the capillary as a long plug. The pH difference between the sample matrix and BGS caused changes in analytes' mobilities during electrophoresis, resulting in narrowing of their bands at the boundary. Around 550-1000-fold sensitivity enhancement could be achieved in terms of peak intensity without degrading peak shape and resolution. This technique is easy to perform and will be useful for peptide mass fingerprinting in protein analysis.
    Journal of Chromatography A 06/2007; 1148(2):250-5. · 4.61 Impact Factor
  • Maria Rowena N Monton, Shigeru Terabe
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    ABSTRACT: Compared to chromatography-based techniques, the concentration limits of detection (CLOD) associated with capillary electrophoresis are worse, and these have largely precluded their use in many practical applications. To overcome this limitation, researchers from various disciplines have exerted tremendous efforts toward developing strategies for increasing the concentration sensitivities of capillary electrophoresis (CE) systems, via the so-called sample enrichment techniques. This review highlights selected developments and advances in this area as applied to the analyses of proteins and peptides in the last 5 years.
    Journal of Chromatography B 10/2006; 841(1-2):88-95. · 2.49 Impact Factor
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    ABSTRACT: A method based on the presence of a dynamic pH junction within the capillary to induce band narrowing for enhanced detection sensitivity for some peptides is presented. This technique is predicated on a sharp reduction in an analyte's migration velocity following a reversal of its electrophoretic direction from the acidic sample zone to the basic BGS zone. Larger-than-usual injection volumes of samples in relatively high-conductivity matrices were enabled, without degrading peak shape, resolution and efficiency. The size of the original sample plug was reduced by as much as 38-fold, and improvement in detector response in terms of peak height by as much as 124-fold was obtained. The effects of pH and concentration of the sample matrix, and the length of sample injection on the efficiency of the technique are discussed.
    Journal of Chromatography A 07/2005; 1079(1-2):266-73. · 4.61 Impact Factor
  • Maria Rowena N Monton, Shigeru Terabe
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    ABSTRACT: Many researchers have invested considerable efforts toward improving capillary electrophoresis (CE)-mass spectrometry (MS) systems so they can be applied better to standard analyses. This review highlights the developments in CE-MS of proteins and peptides over the last five years. It includes the developments in interfaces, sample-enrichment techniques, microfabricated devices, and some applications, largely in capillary zone electrophoresis (CZE), capillary isoelectric focusing (CIEF) and capillary isotachophoresis formats.
    Analytical Sciences 02/2005; 21(1):5-13. · 1.57 Impact Factor
  • Maria Rowena N Monton, Shigeru Terabe
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    ABSTRACT: Field-enhanced sample injection (FESI) was used to improve the concentration sensitivity of a capillary electrophoresis (CE)-mass spectrometry (MS) system with sheath flow configuration. Using some bioactive peptides, more than 3000-fold improvement in signal was obtained, permitting analysis in the low nM (fmol/microl) levels. The system was further evaluated for analysis of complex peptide mixtures by using low concentration tryptic digests of standard proteins. Rapid identification of the original protein was obtained by database searching using the observed molecular masses of the peptides, and by comparison of actual MS-MS spectra of selected peptides with the predicted fragmentation patterns.
    Journal of Chromatography A 05/2004; 1032(1-2):203-11. · 4.61 Impact Factor
  • Source
    Maria Rowena N Monton, Koji Otsuka, Shigeru Terabe
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    ABSTRACT: On-line preconcentration by sweeping in micellar electrokinetic chromatography using mixed micelles of sodium dodecyl sulfate (SDS)-SB-12 is presented. Because of their large micelle radius, they permit increased partitioning of hydrophobic analytes into the core. In addition, they also possess lower negative surface charge relative to pure SDS micelles so anionic analytes can be retained better due to decreased electrostatic repulsion. As the efficiency of sweeping is predicated on the magnitude of retention factors, these advantages translated to better focusing. As much as a 370-fold improvement in detector response, in terms of peak height, was obtained for some neutral steroids, while about a 360-fold improvement was obtained for some phenol derivatives, which were previously not amenable to sweeping by pure SDS micelles.
    Journal of Chromatography A 02/2003; 985(1-2):435-45. · 4.61 Impact Factor
  • Source
    M R Monton, J P Quirino, K Otsuka, S Terabe
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    ABSTRACT: The separation and on-line preconcentration by sweeping of charged analytes in electrokinetic chromatography using a neutral pseudostationary phase is described. Under neutral or basic conditions, the electrophoretic migration of anionic analytes towards the anode is overcome by a high, cathode-directed electroosmotic flow; hence, they experience net migration towards the cathode, and the system is run at positive polarity mode. The separation and the retention factor, k, are dependent on both the analyte's electrophoretic mobility and its interaction with the pseudostationary phase. The versatility of the sweeping mechanism is then shown in this system. The charged analyte, prepared in a matrix free of the pseudostationary phase, penetrates the pseudostationary phase zone upon application of voltage. Analyte molecules are consequently accumulated and concentrated. As a demonstration, the separation and preconcentration of phenol derivatives using nonionic surfactants of the alkyl polyoxyethylene ether type (Brij 35 and Brij 58) yielded peak height enhancements up to 100-fold. The efficiency of sample stacking was also found to be improved with the use of a high viscosity background solution.
    Journal of Chromatography A 01/2002; 939(1-2):99-108. · 4.61 Impact Factor

Publication Stats

303 Citations
37.55 Total Impact Points

Institutions

  • 2006–2007
    • Keio University
      • Institute for Advanced Biosciences
      Tokyo, Tokyo-to, Japan
  • 2005–2007
    • University of Hyogo
      • Graduate School of Material Science
      Akō, Hyogo-ken, Japan
  • 2002–2004
    • Himeji Institute of Technology
      • • Graduate School of Science
      • • Faculty of Science
      Himezi, Hyōgo, Japan