Takahisa Tsugoshi

Characterization of aluminum species with nitrate, perchlorate and sulfate ions in the positive and negative ion mode by electrospray ionization mass spectrometry

The application of electrospray ionization mass spectrometry (ESI-MS) for aluminum speciation in the positive and negative ion modes was discussed. Aluminum nitrate, perchlorate and sulfate solutions were measured by ESI-MS. In the positive ion mode, aluminum species containing anions (Al-L; L=NO3, ClO4 and SO4) were identified, while [Al(OH)2(H2O)n]+ (n=2-4) were the main species. The affinity of the anions with Al3+ estimated by ESI-MS was consistent with the hardness of the anions (hard and soft acids and bases principle) and the results from 27Al nuclear magnetic resonance studies. This indicates that the results observed from the positive ion mode preserved the chemical state of aluminum in the solution. In the negative ion mode, [Al(OH)4-nLn]- (n=0-2, L=NO3, ClO4) were the main species, which were considered to be converted from positive aluminum species, [Al(OH)(H2O)n]+ (n=2-4), by the successive addition of anions. Anions did not only attach to one aluminum ion but also bridged two aluminum ions. In Al2(SO4)3 solution, the behavior of SO4(2-) in the negative ion mode differed from that of NO3- and ClO4-. This may reflect the affinity of SO4(2-) with Al3+ in the solution or in the mass spectrometer or in both. Finally, detection mechanisms for the aluminum species in the solution are proposed for both the positive and negative ion modes. It is shown that ESI-MS can be used to observe the interaction between Al3+ and anions. We show the importance of the interpretation of the results by ESI-MS for obtaining new information of the metal species in the solution.

Ion attachment mass spectrometry combined with infrared image furnace for thermal analysis: evolved gas analysis studies.

A well-established ion attachment mass spectrometer (IAMS) is combined with an in-house single-atom infrared image furnace (IIF) specifically for thermal analysis studies. Besides the detection of many chemical species at atmospheric pressure, including free radical intermediates, the ion attachment mass spectrometer can also be used for the analysis of products emanating from temperature-programmed pyrolysis. The performance and applicability of the IIF-IAMS is illustrated with poly(tetrafluoroethylene) (PTFE) samples. The potential of the system for the analysis of oxidative pyrolysis is also considered. Temperature-programmed decomposition of PTFE gave constant slopes of the plots of temperature versus signal intensity in a defined region and provided an apparent activation energy of 28.8 kcal/mol for the PTFE decomposition product (CF(2))(3). A brief comparison with a conventional pyrolysis gas chromatography/mass spectrometry system is also given.

Characterization of Japanese lacquer liquid and films by means of evolved gas analysis-ion attachment mass spectrometry

We investigated the thermal decomposition of Japanese lacquer liquid and films, which are non-volatile complex natural materials, by means of evolved gas analysis-ion attachment mass spectrometry. The thermal decomposition products are identified by analysis of the mass spectra of degraded samples. The mass chromatogram (pyrogram) of the products generated at various temperatures with kinetic treatments is informative for the characterization of lacquer materials. The H2O pyrogram (obtained in selected-ion-monitoring mode) of a Japanese lacquer film indicated two stages of water release—vaporization and intramolecular H2O elimination—and the kinetics of these two processes were studied. Plots of temperature versus signal intensity at m/z 25 gave constant slopes and provided apparent activation energies of 41.4 and 171 kJ mol−1, respectively, for the two processes.

Evolved gas analysis with skimmer interface and ion attachment mass spectrometry for burnout monitoring of organic additives in ceramic processing.

A monitoring of the individual pyrolysis of mixed polymer as a binder for ceramic processing was carried out as an application of evolved gas analysis-mass spectrometry (EGA-MS) with a skimmer interface and ion attachment mass spectrometry (IAMS). It could detect characteristic species evolved by the pyrolysis of the organic additives, according to the instrumental advantages as the transmission of the gaseous species with no transformation by the skimmer interface and complete soft ionization for gaseous species by IAMS technique. Further, the pyrolysis behavior of blended polymers as a binder could be monitored individually as EGA curves of characteristic species evolved by the pyrolyses.

A study on the utilization of the Youden plot to evaluate proficiency test results

Methods of utilizing the Youden plot obtained from interlaboratory comparison tests are proposed. The Youden plot is a powerful tool for visually evaluating between- or within-laboratory errors. However, there are no generally applicable methods to indicate the anomalies in the between- and the within-laboratory errors in qualitative terms. An evaluation frame was therefore developed in this study as an indication method. Moreover, the Youden plot is considered to be useful for visually assessing the comprehensive performance of laboratories using two types of results. Although the confidence ellipse has been proposed in ISO 13528:2005 for this purpose, robust determination of the parameters has not yet been implemented. In the present study, robust determination of one of the parameters, the correlation coefficient, was developed. Our proposals were analytically validated using two types of statistical models. In addition, the properties were evaluated through computational simulations. From the results obtained, it can be concluded that our proposals are practically applicable to actual interlaboratory comparison tests.

An application of EGA–MS with skimmer interface to pyrolysis behavior of DHTAM, an antibacterial and antifungal material with thermostability

An application of evolved gas analysis-mass spectrometry (EGA-MS) with skimmer interface was carried out to investigate the pyrolysis mechanism of an antibacterial and antifungal material that is expected with thermostability. The skimmer interface between a furnace and a vacuum chamber with a mass spectrometer transmitted the gaseous species, which were trapped by a general capillary interface. As a result, it became clear that the thermostability of antimicrobial activity was limited by the heat resistance of the coordinate bond between nitrogen and silver in the silver chelate.

Fabrication of Al2O3 Ceramics by Environmentally Friendly Process

We have developed a new environmentally friendly fabrication process for alumina ceramics using hydraulic alumina (HA) and water. Without the addition of an organic binder, alumina green bodies retained their original shapes by the hydration of HA in the green bodies. In the case of α-Al2O3-HA-H2O system, alumina ceramics with 97.8% theoretical density were obtained. Added water acted as a fugitive material in the hardened green body. In the case of HA-H2O system, porous alumina ceramics with a wide range of open porosity (56.6–69.1%) and narrow pore size distributions were fabricated without the use of organic fugitive materials. The results of evolved gas analysis-mass spectrometry measurements showed that the new fabrication process for alumina ceramics was confirmed to be eco-friendly.

Synthesis of Nano-Sized Crystallites Using Phase Separated Microenvironments

Hydroxyapatite (HAp) nano-sized crystallites were prepared by a bio-inspired method containing no heating process. Crystal nucleation and growth proceeded within microemulsion, i.e., water droplets surrounded by amphiphilic molecules. Decrease in the diffusion rate of reactants through the structural barrier restricted the crystal growth. The obtained HAp nanocrystallites would be applicable to various medical uses.

Analytical Studies on Laser Microprobe Mass Spectrometry (LAMMS).

It has been difficult to obtain chemical-state information in microprobe analysis. This thesis presents the application and development of laser microprobe mass spectrometry (LAMMS) for this purpose. In the first study, analysis of an insulating polycarbonate surface treated with a silane coupling agent is presented. The surfactant in the agent is effective for generating different chemical species in the treated layers and for their homogenization. The second study describes the sensitive detection of acid components on deteriorated stone. The detection of nitrogen- and sulfur-oxide ions indicates the acceleration of stone deterioration by acid rain. In the third study, a structural interpretation of the silicate network is carried out using the Si/O ratio of the fragment ions. The calculated Si/O ratio coincided with the ratio obtained from the fragment ions detected, depending on the network structure. In the fourth study, the time dependence of ionization is presented. Since a high power laser pulse makes the fine structure of secondary ionization observable, the behavior difference between Al and Au has become clear. In conclusion, LAMMS is useful for sensitive chemical-state and microprobe analysis, especially of insulator materials. Further it is suggested that the interpretation of ionization behavior due to the thermal process has possibility for a new chemical-state analysis.