Yuki Kitahara

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.

Formation of bisphenol A by thermal degradation of poly(bisphenol A carbonate)

The thermal decomposition of poly(bisphenol A carbonate) (PoC) results in the formation of the endocrine disruptor bisphenol A (BPA). In the present work, we investigated the kinetics of the thermal decomposition of PoC, and the subsequent decomposition of BPA, under pyrolysis conditions and in the presence of oxygen by using infrared image furnace-ion attachment mass spectrometry. The decomposition of PoC obeyed Arrhenius kinetics, which allowed us to determine the activation energy (E(a)) for thermal decomposition to BPA from Arrhenius plots. From the selected ion monitoring curves for BPA, E(a) for thermal decomposition in a nitrogen atmosphere was calculated to be 133.2 kcal mol(-1), whereas E(a) for oxidative thermal decomposition was calculated to be approximately 35% lower (86.5 kcal mol(-1)).

Thermal stability of vitamin C: thermogravimetric analysis and use of total ion monitoring chromatograms.

The thermal decomposition kinetics and shelf life of vitamin C in nitrogen or air were studied by using thermogravimetric analysis (TGA) and evolved-gas analysis-lithium-ion attachment mass spectrometry (EGA-Li⁺IAMS). Arrhenius parameters obtained via TGA were reported for thermal decomposition. For vitamin C in a nitrogen atmosphere, the activation energy (E(a)) was 25.1 kcal/mol and the pre-exponential factor (A) was 2.5 × 10¹¹ min⁻¹. The kinetic parameters estimated via TGA agreed with values estimated from a pyrogram when the weight loss observed by TGA was shown to be due to gas evolution as a result of decomposition of the compound. Thermal stability was expressed by calculating the time for 10% of the vitamin C to decompose at 25 °C (t(90%,25 °C)). The t(90%,25 °C) for vitamin C obtained via TGA or EGA-Li⁺IAMS was higher in nitrogen (2.0 and 2.0 years, respectively) than in air (1.3 and 1.6 years, respectively). This indicates that the type of atmosphere influences vitamin C stability.

Temperature-resolved thermal analysis of cisplatin by means of Li+ ion attachment mass spectrometry

Li(+) ion attachment mass spectrometry (IAMS) was evaluated as an analytical methodology for measurement of the thermally labile, nonvolatile, and insoluble compound cisplatin, which is used as an anticancer agent in the treatment of testicular and ovarian cancers. We aimed to develop an improved method for the mass spectrometric determination of cisplatin, particularly in its molecular ion form. A uniquely designed quadrupole mass spectrometry system along with a Li(+) ion attachment technique and a direct inlet probe provided cisplatin molecular ions as Li(+) ion adducts; to our knowledge this is the first reported instance of cisplatin Li(+) ion adducts. Full-scan spectra were obtained with approximately 10 microg samples. Infrared image furnace-ion attachment mass spectrometry (IIF-IAMS) also was used to study the temperature-programmed decomposition of this drug. The slope of the plot of signal intensity versus temperature for cisplatin decomposition from 225 to 249 degrees C was used to determine an apparent activation energy (E(a)) of 38.0 kcal mol(-1) for the decomposition of cisplatin. This decomposition parameter is useful for predicting drug stability (shelf life). In this study, we have demonstrated that IAMS can be a valuable technique for the direct mass spectral analysis and kinetic study of d-metal complex platinum anticancer agents.

Thermal analysis of polyethylene glycol: Evolved gas analysis with ion attachment mass spectrometry

The thermal decomposition of polyethylene glycol was investigated by using a technique combining evolved gas analysis (time-resolved pyrolysis) with ion-attachment mass spectrometry. This technique allows the detection of intact pyrolysis products and, therefore, offers the opportunity for direct real-time monitoring of thermal by-products. Unstable products can thus be detected; for instance, many highly reactive organic peroxides, such as CH(3)OOH and HOCH(2)OOH, were found in this study. Classification analysis revealed 10 major compositional formulas among the product species: C(n)H(2)(n)(+2)O, C(n)H(2)(n)(+2)O(2), C(n)H(2)(n)(+2)O(3), C(n)H(2)(n)(+2)O(4), C(n)H(2)(n)(+2)O(5), C(n)H(2)(n)(+2)O(6), C(n)H(2)(n)(+2)O(7), C(n)H(2)(n)O, C(n)H(2)(n)O(2), and HO(CH(2)CH(2)O)(n)H ethylene glycol oligomers. The Li(+) ion adduct mass spectra showed a characteristic profile in terms of both the appearance of unique components and the distribution of pyrolysis products. Among the products of the thermal decomposition of PEG, formaldehyde (HCHO) and organic peroxides were particularly interesting. Formaldehyde, one of the 10 most abundant products, is a known human carcinogen. The detection of peroxides suggests that they may form during the incineration of PEG, which may have important environmental implications. The existence of peroxide products may have implications for chemical evolution in incinerator systems.

Design and performance of an evolved gas analysis ion attachment mass spectrometer

We designed a simple evolved gas analysis (EGA) system to act as a sampler between solid samples at atmospheric pressure and the high vacuum inside a mass spectrometer. The newly designed stainless steel system is simple, small and rugged and fulfills all the basic requirements for EGA. The temperature is programmable with 60 degrees C/min as the maximum heating rate and the temperature range is up to 600 degrees C. With this system coupled with lithium ion attachment mass spectrometry (IAMS), it is possible to study the temperature-programmed decomposition of a number of solid materials by detecting any chemical species on a real-time basis. For illustrative purposes, EGA-IAMS experiments of polyethylene polymers have been conducted.

Effect of atmosphere and catalyst on reducing bisphenol A (BPA) emission during thermal degradation of polycarbonate.

Bisphenol A (BPA), a well-known endocrine disruptor, is one of the major products in the thermal degradation of polycarbonate (PC) and is also leached out from various PC products. Because of the high acute toxicity of BPA, reducing BPA production during degradation of PC is an important topic. A combined Infrared Image Furnace with Ion attachment mass spectrometry technique was used to investigate the evolution of BPA from a PC sample during heating in either nitrogen or air atmosphere and with or without a CuCl(2) catalyst. Thermal treatment in the presence of CuCl(2), in nitrogen atmospheres and at lower degradation temperatures, substantially reduced the BPA emission.

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.

Thermal decomposition of vitamin C: An evolved gas analysis−ion attachment mass spectrometry study

Evolved gas analysis-ion attachment mass spectrometry (EGA-IAMS) was utilised to study the real-time non-isothermal decomposition of vitamin C. Dehydro-l-ascorbic acid, which has until this study been undetectable from the solid phase degradation of vitamin C, was observed as a decomposition product. While it is an important compound because it possesses some biological activity, dehydro-l-ascorbic acid is difficult to measure due to its chemical instability. In the present study using EGA-IAMS, we were able to detect dehydro-l-ascorbic acid from the thermal degradation of vitamin C. Our EGA-IAMS results obtained from the thermal decomposition of vitamin C were compared with a previous study employing pyrolysis-gas chromatography-mass spectrometry (Pyr-GC-MS). The observed quantitative and qualitative differences of the pyrolysis products obtained by the two techniques (EGA-IAMS vs. Pyr-GC-MS) are in part due to the difference in transportation time of the products out of the pyrolysis chamber.

Evolved gas analysis–ion attachment mass spectrometric observation of Mn(CO)5 and Mn2(CO)9 radicals produced by Mn2(CO)10 pyrolysis

Evolved gas analysis–ion-attachment mass spectrometry (EGA–IAMS) indicates that Mn(CO)5 and Mn2(CO)9 free radicals are produced in the gas phase by pyrolysis of Mn2(CO)10 in an infrared image furnace. The Li+-adduct mass spectra of the pyrolysis products contained peaks at m/z 202 and 369 for Mn(CO)5Li+ and Mn2(CO)9Li+, respectively, providing direct evidence that d-metal complex radicals were formed in the furnace. We studied the effect of temperature on the rate of production of the radicals, and confirmed the presence of the compounds Mn(CO)5 and Mn2(CO)9, which were reported in earlier studies based on electron-impact mass spectrometry, electron spin resonance spectroscopy, and Fourier transform infrared spectroscopy.