JMSSJ On-line Abstracts, Vol.49, No.3 (2001)
English
Chiaki UYEDA* ( Institute of Earth and Space Science, Graduate School of Science, Osaka University (1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan) e-mail: uyeda@ess.sci.Osaka-u.ac.jp )
J. Mass Spectrom. Soc. Jpn., 49(3), 83-88, 2001
The problems in investigating the thermal history of the primordial solar nebula from the isotopic mass fractionation data are discussed based on the compiled data of primitive materials as well as on the results of reproducing experiments. The results of the experiments showed that isotopic mass fractionation is dominated by various conditions which may vary considerably in the nebula. The fractionation process is controlled for example by the state of the evaporation source, the rate of evaporation and the rate of source mixing as well as the molecular species of the gas phase. Hence at present, one cannot estimate the thermal origin of the large mass fractionation observed in the refractory inclusions of the primitive meteorites. In order to estimate the thermal history from the mass fractionation data, further experiments should be preformed to understand the kinetic behavior of molecules during the evaporation and condensation process in the nebula. At the same time, isotopic data should be accumulated over various mineral phases having different origins in the meteorite. The isotopic in-situ survey on sections of primitive material should be performed over a wide area with high spatial resolution for effective data accumulation.
Japanese, English Abstract
Fumiyo KASUYA ( Faculty of Pharm
aceutical Sciences, Kobe-gakuin University ( 518, Arise, Ikawadani, Nishi-ku, Kobe 651-2180, Japan) )
J. Mass Spectrom. Soc. Jpn., 49(3), 89-95, 2001
Glycine conjugation is the most important route of detoxification, not only of many xenobiotic carboxylic acids but also of endogenous acids. However, the first reaction of glycine conjugation in some cases is reported to involve a class of active intermediates implicated in toxicity. The pathway of glycine conjugation consists of two sequential reactions. To elucidate the factors that regulate glycine conjugation, benzoic acid derivatives, acyl-CoAs as the active intermediates and glycine conjugates were simultaneously determined by LC-ESI-MS. Three compounds were collected from the microdialysis probe immersed into mitochondrial incubation mixture. A rate-limiting step was found to be the linkage to the amino group of glycine in a reaction that is catalyzed by acyl-CoA glycine: N-acyltransferases. However, the medium chain acyl-CoA synthetase catalyzing the initial reaction of glycine conjugation was the rate-limiting enzyme. Further, it was suggested that the stability of acyl-CoAs is one of the factors that determine the metabolic fate of xenobiotics containing a carboxylic group.
Japanese, English Abstract
Yoshitaka ICHIKAWA ( Tsukuba Research Laboratories, GlaxoSmithKline K.K. ( 43 Wadai, Tsukuba 300-4247, Japan) )
J. Mass Spectrom. Soc. Jpn., 49(3), 96-102, 2001
Since advent of atmospheric pressure ionization technique, LC/MS had been used very often for bioanalysis at early to late drug development stage. Then, LC/MS have been principal equipment for bioanalysis especially for high sensitivity and high throughput purposes, at present. Lately, the automatic sample pretreatment using robotics accelerates the improvement of throughput and
releases a researcher from pretreatment work. On the other side, high speed analysis methods carried some problems for misunderstanding of analytical data. Still, those problems could be manageable with appropriate expertise and experience.
Japanese, English Abstract
Noriko OHASHI*a), Yutaka TAKAHASHIb), Kenji MATSUURAc), Kuniharu SUZUMURAa), Mikiko YASUHARAa), Toshiyuki KUMEa), and Masayoshi YOSHIKAWAa) ( *a) DiscoveryResearchLaboratory,TanabeSeiyakuCo.,Ltd. (2-2-50 Kawagishi, Toda 335-8505, Japan) b)MS R & D Department, Analytical Instruments Division, JEOL Ltd. (3-1-2 Musashino, Akishima 196-0021, Japan) c) Analytical Instruments Training & Application Center, JEOLDATUMLtd.(1418Nakagami-machi, Akishima 196-0022, Japan))
J. Mass Spectrom. Soc. Jpn., 49(3), 103-106, 2001
The isoprostane, 8-iso-PGF2a is formed from arachidonic acid in vivo by a mechanism independent of cyclooxygenase pathway. We developed a new assay method for 8-iso-PGF2a using [2H4]-8-iso-PGF2a as the internal standard (I.S.) by LC-ESI/MS. For this assay, we established a very simple and rapidly pretreatment method using a membrane filter-type solid phase extraction column (EmporeTM disk cartridge) for human plasma and urine. LC-ESI/MS was performed in the selected ion monitoring (SIM) mode using target ions at m/z 353.4757 (8-iso-PGF2a) and m/z 357.5073 (I.S.) with a resolution of 3,000. The imprecision for this method was below14%. Mean inaccuracy was 9%
for added levels of 8-iso-PGF2a up to 5,000 pg/mL of urine and 500 pg/mL of plasma. The study of human urinary and plasma 8-iso-PGF2a concentrations may be a convenient diagnostic tool to be able to assess the extent of oxidative stress in vivo not only by smoking but also in other disease states.
English
Takaya SATOH,*a) Takeshi NAGATA,a) Hiroki SAKAE,a) Hiroyuki ITO,a) Toshio ICHIHARA,a) and Itsuo KATAKUSEa) ( *a) Department of Physics, Graduate School of Science, Osaka University (Machikaneyama 1-16, Toyonaka, Osaka 560-0043, Japan) )
J. Mass Spectrom. Soc. Jpn., 49(3), 121-126, 2001
The size distribution of iron-sulfur binary cluster ions, FenS
( n=1-36, m=1-23), was investigated using secondary ion mass spectrometry (SIMS). The dissociation patterns, n=2-26, m=1-17, were also investigated by varying the acceleration voltage of secondary ions step by step. Iron-sulfur binary cluster ions were produced by 10 keV Xe ion bombardment on a pyrite (FeS2) sheet and were mass-analyzed by a sector type mass spectrometer. Judging from the size distribution observed in mass spectra, the composition ratio n/m of the cluster ions gradually tended to increase as the cluster size became larger. The dissociation patterns of small size tended to yield the FenS
(n=2, 4, 6) and FenS
(n=7, 8, 9) which might be more stable structure. As the cluster size became larger, the dissociation mainly occurred by emitting Fe or S2. Dissociation patterns of FenS suddenly changed at FenS
which had maximum peak intensity in the series of FenS for the fixed n. In case of m
M, Fe emission occurred and S2 emission for m>M.
English
Kozo MATSUMOTO,a) Hiroharu AJIRO,a) Shigeki HABAUE,a) and Yoshio OKAMOTO*a) ( *a) Department of Applied Chemistry, Graduate School of Engineering, Nagoya University (Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan) )
J. Mass Spectrom. Soc. Jpn., 49(3), 127-132, 2001
A TLC-MALDI-TOFMS system has been developed for rapid identification of compounds in a mixture produced in an organic synthetic reaction. In this method, only main compounds were only identified. In the present work, some modifications were added to the TLC-MALDI-TOFMS system in order to detect minor components existing in the mixture at a much lower level. Detection limits attained by this modified system were comparable with that of a conventional MALDI-TOFMS system.
