著者

Ami Kageyama (Kaneshima) Akira Motoyama Mitsuo Takayama

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.8, no.1, pp.A0077, 2019-11-30 (Released:2019-11-30)

参考文献数

24

被引用文献数

7

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The influence of solvent composition and surface tension on the signal intensity of deprotonated molecules [M−H]− in electrospray ionization mass spectrometry (ESI MS) was evaluated using alanine (Ala), threonine (Thr) and phenylalanine (Phe), which have differing levels of hydrophobicity. The surface tension of the ESI solution was varied by changing the ratio of the organic solvents methanol (MeOH) and acetonitrile (MeCN) in water (H2O). In ESI MS, the signal intensity of all the amino acids was increased with decreasing surface tension for the two solutions, H2O/MeOH and H2O/MeCN. The use of H2O/MeCN was more favorable for achieving a strong signal for the analytes compared to H2O/MeOH. The smaller vaporization enthalpy of MeCN compared to MeOH was proposed as one of the most plausible explanation for this. The order of the signal intensity of amino acids was Phe>Thr>Ala, the same order as their hydrophobicity. It can be practically concluded that the use of solutions with lower surface tensions and lower vaporization enthalpies would result in higher signal intensities in ESI MS.

著者

Hisao Nakata

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.8, no.1, pp.A0074, 2019-11-25 (Released:2019-11-25)

参考文献数

46

被引用文献数

4

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Typical modes of bond cleavages of organic compounds in mass spectrometry are briefly summarized. Although these fragmentation rules can be quite useful for interpreting mass spectra of simple compounds, application to structurally complex molecules that contain multiple hetero atoms such as nitrogen or oxygen becomes increasingly difficult, because the exact location of an unpaired electron or positive or negative charges becomes obscure in precursor ions.About a decade ago, we proposed “a rule of mass shift,” which correctly predicts the m/z for observed peaks corresponding to singly charged even-electron fragment ions. The basis of the rule postulates that ions observed as peaks in an ordinary mass spectrum should be sufficiently stable to survive during the flight path in a mass spectrometer.The important recognition is that each atom in a stable ion should be in an ordinary valence state, and no free valence should be allowed. Therefore, if the cleavage of a bond leads to an ion with an unstable structure, some structural changes must take place in order for the ion to be observed in the mass spectrum. Such structural changes can be the addition of hydrogen atom(s) and/or a proton for positive ions, and the addition of a hydrogen atom and/or the elimination of two hydrogen atoms in the case of negative ions. These required structural changes in each case are schematically depicted and discussed in detail.Two typical examples are shown, in which m/z’s of the observed peaks are correctly predicted. The scope and limitations, as well as the significance of the rule for analyzing fragmentations in organic mass spectrometry are also discussed.

著者

Nobuyuki Okahashi Shuichi Kawana Junko Iida Hiroshi Shimizu Fumio Matsuda

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.8, no.1, pp.A0073, 2019-08-30 (Released:2019-08-30)

参考文献数

15

被引用文献数

1 18

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Isotope labeling measurements using mass spectrometry can provide informative insights on the metabolic systems of various organisms. The detailed identification of carbon positions included in the fragment ions of dicarboxylic and tricarboxylic acids in central carbon metabolism is needed for precise interpretation of the metabolic states. In this study, fragment ions containing the carbon backbone cleavage of dicarboxylic and tricarboxylic in the Krebs cycle were investigated by using gas chromatography (GC)-electron ionization (EI)-MS and GC-EI-MS/MS. The positions of decarboxylation in the dicarboxylic and tricarboxylic acids were successfully identified by analyses using position-specific 13C-labeled standards prepared by in vitro enzymatic reactions. For example, carboxyl groups of C1 and C6 of trimethylsilyl (TMS)- and tert-butyldimethylsilyl (TBDMS)-derivatized malic and citric acids were primarily cleaved by EI. MS/MS analyses were also performed, and fragment ions of TBDMS-citric and α-ketoglutaric acids (αKG) with the loss of two carboxyl groups in collision-induced dissociation (CID) were observed.

著者

Kanako Sekimoto Motoshi Sakakura Hiroshi Hike Takatomo Kawamukai Teruhisa Shiota Mitsuo Takayama

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.8, no.1, pp.A0075, 2019-10-25 (Released:2019-10-25)

参考文献数

36

被引用文献数

1

---

Herein, a dark-current discharge state created by combining argon flow with a needle electrode in ambient air is described that has an ionization efficiency and mechanism comparable to those of conventional helium direct analysis in real time (DART), without requiring dopants and DART glow discharge. Using this method, polar compounds such as α-amino acids were ionized in the dark-current argon discharge via (de)protonation, molecular anion formation, fragmentation, (de)protonation with the attachment of oxygen, deprotonation with hydrogen loss and negative ion attachment. In contrast, nonpolar compounds (e.g., n-alkanes) were detected as positive ions via hydride abstraction and oxidation. Major background ions observed were H3O+(H2O)n, O2·+, O2·−(H2O)n and CO3·−. These results indicate that the present dark-current discharge efficiently generates resonance-state argon with an internal energy of ∼14.2 eV, higher than that of the well-known metastable state (∼11.6 eV). It is therefore suggested that ionization reactions occurring there can be attributed to the Penning ionization of atmospheric H2O and O2 by resonance-state argon, analogous to helium DART.

著者

Bui Kamihoriuchi Yoichi Otsuka Aya Takeuchi Futoshi Iwata Takuya Matsumoto

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.7, no.2, pp.S0078, 2019-03-06 (Released:2019-03-07)

参考文献数

22

被引用文献数

1 7

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Ambient sampling and ionization techniques based on direct liquid extraction and electrospray ionization are of great value for rapid analysis and mass spectrometry imaging. Scanning probe electrospray ionization (SPESI) enables the sampling and ionization of analyte molecules in a solid material using a liquid bridge and electrospray, respectively, from a single capillary probe. To further improve SPESI, it is essential to understand the dynamic behavior of nanoliter volumes of liquids during sampling and ionization. In this study, the dynamic formation and breakage of the liquid bridge and the subsequent electrospray ionization were investigated by measuring the displacement of the capillary probe using a new optical technique. Measurements revealed that both the time from the formation of the liquid bridge to its breakage and the time from the breakage of the liquid bridge to the detection of analyte ions were correlated with the physical properties of the solvent. It was also found that both of these times were positively correlated with the flow rate. These results will not only lead to the improvement of sampling and ionization efficiencies but also afford a greater understanding of the physicochemical properties of charged nanoliter volumes of liquids.

著者

Nobuyuki Okahashi Shuichi Kawana Junko Iida Hiroshi Shimizu Fumio Matsuda

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

pp.A0073, (Released:2019-08-01)

参考文献数

15

被引用文献数

18

---

Isotope labeling measurements using mass spectrometry can provide informative insights on the metabolic systems of various organisms. The detailed identification of carbon positions included in the fragment ions of dicarboxylic and tricarboxylic acids in central carbon metabolism is needed for precise interpretation of the metabolic states. In this study, fragment ions containing the carbon backbone cleavage of dicarboxylic and tricarboxylic in the Krebs cycle were investigated by using gas chromatography (GC)-electron ionization (EI)-MS and GC-EI-MS/MS. The positions of decarboxylation in the dicarboxylic and tricarboxylic acids were successfully identified by analyses using position-specific 13C-labeled standards prepared by in vitro enzymatic reactions. For example, carboxyl groups of C1 and C6 of trimethylsilyl (TMS)- and tert-butyldimethylsilyl (TBDMS)-derivatized malic and citric acids were primarily cleaved by EI. MS/MS analyses were also performed, and fragment ions of TBDMS-citric and α-ketoglutaric acids (αKG) with the loss of two carboxyl groups in collision-induced dissociation (CID) were observed.

著者

Toshihiro Suzuki Shuhei Sakata Yoshiki Makino Hideyuki Obayashi Seiya Ohara Kentaro Hattori Takafumi Hirata

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.7, no.1, pp.A0065-A0065, 2018-02-23 (Released:2018-03-01)

参考文献数

14

被引用文献数

37

---

We report on the development of a software program named iQuant2 which creates visual images from two-dimensional signal intensity data obtained by a laser ablation-ICP-mass spectrometry (LA-ICPMS) technique. Time-resolved signal intensity profiles can be converted to position resolved signal intensity data based on the rastering rate (μm s−1) of the laser ablation. Background signal intensities obtained without laser ablation (gas blank) are used as the background, and all of the blank-subtracted intensity data can be used for the imaging analysis. With this software, deformation of the created image can be corrected visually on a PC screen. The line profile analysis between the user-selected points can be observed using the iQuant2 software. To accomplish this, data points on the profile line were automatically calculated based on the interpolation between the analysis points. The resulting imaging data can be exported and stored as JPEG, BMP or PNG formats for further processing. Moreover, a semi-quantitative analysis can be made based on the coupling of the external correction of the RSF (relative sensitivity factor) using NIST SRM610 with normalization of the corrected signal intensity data being 100%. The calculated abundance data for major elements are in reasonable agreement with the values obtained by electron probe micro analyzer (EPMA). With the software developed in this study, both the rapid imaging and semi-quantitative determinations can be made.

著者

Tohru Yamagaki

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.6, no.3, pp.K0011-K0011, 2017-09-11 (Released:2017-09-15)

著者

Chi-Wei Lee Hung Su You-Da Cai Ming-Tsang Wu Den-Chyang Wu Jentaie Shiea

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.6, no.2, pp.S0056-S0056, 2017-03-31 (Released:2017-03-28)

参考文献数

18

被引用文献数

2 20

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Psychoactive drug overdoses are life-threatening and require prompt and proper treatment in the emergency room to minimize morbidity and mortality. Prompt identification of the ingested psychoactive drugs is challenging, since witness recall is unreliable and patients’ symptoms do not necessarily explain their loss of consciousness. Gas and liquid chromatography mass spectrometric analyses have been the traditionally employed methods to detect and identify abused substances; however, these techniques are time-consuming and labor-intensive. In this study, thermal desorption electrospray ionization mass spectrometry, an ambient mass spectrometric technique, was applied to rapidly characterize flunitrazepam, lysergic acid diethylamide, and 3,4-methylenedioxy-methamphetamine in drained gastric lavage fluid, and ketamine, cocaine, amphetamine and norketamine in whole blood samples. No pretreatment of the gastric lavage fluid specimens was required and the entire analytical process took less than 30 s per specimen. Liquid–liquid extraction, followed by centrifugation, was performed on the whole blood samples. The corresponding compounds were identified through matching the obtained mass spectrometric data with those provided by commercial databases. The limits-of-detection of the tested drugs in both drained gastric lavage fluid and whole blood samples are at sub ppm levels. This is sensitive enough for emergency medical application, since the quantities of medications ingested by overdosed abusers are much higher than the amounts that were tested.

著者

Fumio Matsuda

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.5, no.2, pp.S0052-S0052, 2016-11-23 (Released:2016-11-25)

参考文献数

105

被引用文献数

37

---

Metabolomics is a strategy for analysis, and quantification of the complete collection of metabolites present in biological samples. Metabolomics is an emerging area of scientific research because there are many application areas including clinical, agricultural, and medical researches for the biomarker discovery and the metabolic system analysis by employing widely targeted analysis of a few hundred preselected metabolites from 10–100 biological samples. Further improvement in technologies of mass spectrometry in terms of experimental design for larger scale analysis, computational methods for tandem mass spectrometry-based elucidation of metabolites, and specific instrumentation for advanced bioanalysis will enable more comprehensive metabolome analysis for exploring the hidden secrets of metabolism.

著者

Sayaka Nakamura Hiroaki Sato Reiko Tanaka Takashi Yaguchi

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.5, no.1, pp.A0049-A0049, 2016-11-10 (Released:2016-11-08)

参考文献数

28

被引用文献数

11

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We have previously proposed a rapid identification method for bacterial strains based on the profiles of their ribosomal subunit proteins (RSPs), observed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). This method can perform phylogenetic characterization based on the mass of housekeeping RSP biomarkers, ideally calculated from amino acid sequence information registered in public protein databases. With the aim of extending its field of application to medical mycology, this study investigates the actual state of information of RSPs of eukaryotic fungi registered in public protein databases through the characterization of ribosomal protein fractions extracted from genome-sequenced Aspergillus fumigatus strains Af293 and A1163 as a model. In this process, we have found that the public protein databases harbor problems. The RSP names are in confusion, so we have provisionally unified them using the yeast naming system. The most serious problem is that many incorrect sequences are registered in the public protein databases. Surprisingly, more than half of the sequences are incorrect, due chiefly to mis-annotation of exon/intron structures. These errors could be corrected by a combination of in silico inspection by sequence homology analysis and MALDI-TOF MS measurements. We were also able to confirm conserved post-translational modifications in eleven RSPs. After these verifications, the masses of 31 expressed RSPs under 20,000 Da could be accurately confirmed. These RSPs have a potential to be useful biomarkers for identifying clinical isolates of A. fumigatus.

著者

Joseph A. Loo Sabrina A. Benchaar Jiang Zhang

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.2, no.Special_Issue, pp.S0013-S0013, 2013-04-15 (Released:2013-05-03)

参考文献数

35

被引用文献数

2 5

---

Native protein mass spectrometry (MS), the measurement of proteins and protein complexes from non-denaturing solutions, with electrospray ionization (ESI) has utility in the biological sciences. Protein complexes exceeding 1 MDa have been measured by MS and ion mobility spectrometry (IMS), and the data yields information not only regarding size, but structural details can be revealed also. ESI-IMS allows the relative stability of protein–ligand binding to be measured. Top-down MS, the direct dissociation of the intact gas phase biomolecule, can generate sequence and identity information for monomeric (denatured) proteins, and topology information for noncovalent protein complexes. For protein complexes with small molecule ligands, i.e., drugs, cofactors, metals, etc., top-down MS with electron capture dissociation can be used to elucidate the site(s) of ligand binding. Increasing protein ESI charging, e.g., supercharging, enhances the efficiency for dissociation of protein complexes.

著者

Carlito B. Lebrilla

出版者

日本質量分析学会

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.2, no.Special_Issue, pp.S0016-S0016, 2013-04-15 (Released:2013-05-03)

参考文献数

18

被引用文献数

1 3

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The role of glycosylation and their biological functions whether as free oligosaccharides or glycoconjugates has been made possible by the recent advancements in the analyses of these compounds. The heterogeneity and the large structural diversity have made oligosaccharide analysis significantly more difficult than other biopolymers. The next stage of development is to achieve high throughput analysis. However, the structural elucidation of oligosaccharides remains an extremely difficult task. Recent reports reveal that the diversity of structures in a given biological system is finite and may not be large. It may be possible to create a database of structures that can be used to determine the identity of known compounds. This capability would therefore make high throughput glycomics possible. Achieving this task depends on the proper selection of chemical characteristics to identify the compound. In this presentation, nanoflow liquid chromatography retention times, accurate mass, and tandem MS is used to determine structure with a high degree of certainty. The method is used to determine the biological function of milk oligosaccharides as well as to discover glycan-based biomarkers for diseases.

著者

Hiroaki Sato Yoko Ishii Hikaru Momose Takafumi Sato Kanae Teramoto

出版者

The Mass Spectrometry Society of Japan

雑誌

Mass Spectrometry (ISSN:2187137X)

巻号頁・発行日

vol.2, no.1, pp.A0014, 2013-02-01 (Released:2013-01-31)

参考文献数

22

被引用文献数

10 13

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The structural characterization of copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) remains a challenging task, since their random comonomer distribution creates very complicated mass spectra. In this study, a high-resolution TOF mass spectrometer with a spiral ion trajectory was applied to the structural and compositional characterization of free radical copolymerized poly(methyl methacrylate-co-tert-butyl methacrylate), poly(MMA-co-tBMA)s in ethyl lactate acting as a chain transfer agent. Virtually complete peak assignments of the isobaric components within the poly(MMA-co-tBMA)s served to identify the end-group combinations and copolymer compositions of individual copolymer components, allowing the distributions of comonomer compositions and six types of end-group combinations to be evaluated.