質量分析、質量スペクトル分析

関: mass spectrometric、mass spectrometry、mass spectroscopy、MS

WordNet

join together into a mass or collect or form a mass; "Crowds were massing outside the palace"
the property of a body that causes it to have weight in a gravitational field
a body of matter without definite shape; "a huge ice mass"
an ill-structured collection of similar things (objects or people)
an investigation of the component parts of a whole and their relations in making up the whole
the abstract separation of a whole into its constituent parts in order to study the parts and their relations (同)analytic thinking
a branch of mathematics involving calculus and the theory of limits; sequences and series and integration and differentiation
a form of literary criticism in which the structure of a piece of writing is analyzed
the use of closed-class words instead of inflections: e.g., `the father of the bride instead of `the brides father
an ordered array of the components of an emission or wave
a broad range of related objects or values or qualities or ideas or activities
(Roman Catholic Church and Protestant Churches) the celebration of the Eucharist
a musical setting for a Mass; "they played a Mass composed by Beethoven"
a sequence of prayers constituting the Christian Eucharistic rite; "the priest said Mass"
informal terms for a mother (同)mama, mamma, mom, momma, mommy, mammy, mum, mummy

PrepTutorEJDIC

Mississippi
〈C〉(一定の形をもたない物に用いて)…の)『固まり』,集まり《+『of』+『名』》 / 〈C〉『多数』,多量(の…)《+『of』+『名』》 / 〈C〉《the ~》『大部分』(の…),(…の)主要部《+『of』+『名』》 / 〈U〉(物体の)大きさ,かさ / 《the masses》『一般大衆』,庶民 / 〈U〉質量(物体の基本的性質を表す量) / 〈人・物〉‘を'集める,一団にする / 〈人・物が〉一かたまりになる,一団となる / 大衆の,一般に付及した / 大規模な
(内容・状況などの)『分析』,分解;(詳細な)検討 / (化学・物理で)分析;《米》(心理学で)[精神]分析;(数学で)解析
スペクトル(光がプリズムを通過するとき生じる色の帯) / (電磁波・音波などの)範囲,スペクトル / (多様だが関連あるものの)連続[範囲]《+『of』+『名』》
《M-》《話》おかあちゃん(mamma)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/03/02 01:05:21」(JST)

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[Wiki en表示]

Mass-spectrum analysis is an integral part of mass spectrometry.^[1]^[2] Organic chemists obtain mass spectra of chemical compounds as part of structure elucidation and the analysis is part of every organic chemistry curriculum.

Basic peaks

Electron ionization mass spectra have several distinct sets of peaks: the molecular ion, isotope peaks, fragmentation peaks,metastable peaks.

In the mass spectra the molecular ion peak is often most intense, but can be weak or missing. The molecular ion is a radical cation (M+.) as a result of removing one electron from the molecule. Identification of the molecular ion can be difficult. Examining organic compounds, the relative intensity of the molecular ion peak diminishes with branching and with increasing mass in a homologous series. In the spectrum for toluene for example, the molecular ion peak is located at 92 m/z corresponding to its molecular mass. Molecular ion peaks are also often preceded by a M-1 or M-2 peak resulting from loss of a hydrogen radical or dihydrogen.

The peak with the highest intensity is called the base peak which is not necessarily the molecular ion.

More peaks may be visible with m/z ratios larger than the molecular ion peak due to isotope distributions, called isotope peaks. The value of 92 in the toluene example corresponds to the monoisotopic mass of a molecule of toluene entirely composed of the most abundant isotopes (1H and 12C). The so-called M+1 peak corresponds to a fraction of the molecules with one higher isotope incorporated (2H or 13C) and the M+2 peak has two higher isotopes. The natural abundance of the higher isotopes is low for frequently encountered elements such as hydrogen, carbon and nitrogen and the intensity of isotope peaks subsequently low. In halogens on the other hand, higher isotopes have a large abundance which results in a specific mass signature in the mass spectrum of halogen containing compounds.

Peaks with mass less than the molecular ion are the result of fragmentation of the molecule. Many reaction pathways exist for fragmentation, but only newly formed cations will show up in the mass spectrum, not radical fragments or neutral fragments.

Metastable peaks are broad peaks with low intensity at non-integer mass values. These peaks result from ions with lifetimes shorter than the time needed to traverse the distance between ionization chamber and the detector.

Fragmentation

The fragmentation pattern of the spectra beside the determination of the molar weight of an unknown compound also suitable to give structural information, especially in combination with the calculation of the degree of unsaturation from the molecular formula (when available). Neutral fragments frequently lost are carbon monoxide, ethylene, water, ammonia, and hydrogen sulfide.

fragmentations arise from:

homolysis processes. An example is the cleavage of carbon-carbon bonds next to a heteroatom

In this depiction single-electron movements are indicated by a single-headed arrow.

Rearrangement reactions, for example a retro Diels-Alder reaction extruding neutral ethylene:

or the McLafferty rearrangement. As it is not always obvious where a lone electron resides in a radical cation a square bracket notation is often used.

Some general rules:

A useful aid is the nitrogen rule: if the m/z ratio is an even number, the compound contains no nitrogen or an even number of nitrogens.
Cleavage occurs at alkyl substituted carbons reflecting the order generally observed in carbocations.
Double bonds and arene fragments tend to resist fragmentation.
Allylic cations are stable and resist fragmentation.
the even-electron rule stipulates that even-electron species (cations but not radical ions) will not fragment into two odd-electron species but rather to another cation and a neutral molecule.

Toluene example

The mass spectrum for toluene has around 30 signals. Several peaks can be rationalized in this fragmentation pattern.

Isotope effects

Isotope peaks within a spectra can help in structure elucidation. Compounds containing halogens (especially chlorine and bromine) can produce very distinct isotope peaks. The mass spectrum of methylbromide has two prominent peaks of equal intensity at m/z 94 (M) and 96 (M+2) and then two more at 79 and 81 belonging to the bromine fragment.

Even when compounds only contain elements with less intense isotope peaks (carbon or oxygen), the distribution of these peaks can be used to assign the spectrum to the correct compound. For example, two compounds with identical mass of 150 Da, C₈H₁₂N₃⁺ and C₉H₁₀O₂⁺, will have two different M+2 intensities which makes it possible to distinguish between them.

Natural abundance of some elements

The next table gives the isotope distributions for some elements. Some elements like phosphorus and fluorine only exist as a single isotope, with a natural abundance of 100%.

**Natural abundance of some elements** ^[3]
Isotope	% nat. abundance	atomic mass
¹H	99.985	1.007825
²H	0.015	2.0140
¹²C	98.89	12 (definition)
¹³C	1.11	13.00335
¹⁴N	99.64	14.00307
¹⁵N	0.36	15.00011
¹⁶O	99.76	15.99491
¹⁷O	0.04
¹⁸O	0.2	17.99916
²⁸Si	92.23	27.97693
²⁹Si	4.67	28.97649
³⁰Si	3.10	29.97376
³²S	95.0	31.97207
³³S	0.76	32.97146
³⁴S	4.22	33.96786
³⁷Cl	24.23
³⁵Cl	75.77	34.96885
⁷⁹Br	50.69	78.9183
⁸¹Br	49.31	80.9163

References

^ Spectrometric identification of organic compounds Silverstein, Bassler, Morrill 4th Ed.
^ Organic spectroscopy William Kemp 2nd Ed.ISBN 033342171
^ Lide, D. R., ed. (2002). CRC Handbook of Chemistry and Physics (83rd ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0483-0.

UpToDate Contents

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English Journal

Systematic analysis of silver nanoparticle ionic dissolution by tangential flow filtration: toxicological implications.

Maurer EI, Sharma M, Schlager JJ, Hussain SM.Author information 711 Human Performance Wing/RHDJ, Human Effectiveness Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base , Dayton, Ohio , USA.AbstractAbstract In the field of toxicology of nanomaterials, scientists have not clearly determined if the observed toxicological events are due to the nanoparticles (NPs) themselves or the dissolution of ions released into the biophysiological environment or both phenomenon participate in combination based upon their bioregional and temporal occurrence during exposure conditions. Consequently, research involving the toxicological analysis of silver NPs (Ag-NPs) has shifted towards assessment of 'nanosized' silver in comparison to its solvated 'ionic' counterpart. Current literature suggests that dissolution of ions from Ag-NPs may play a key role in toxicity; however, the present assessment methodology to separate ions from NPs still requires improvement before a definitive cause of toxicity can be determined. Recently, centrifugation-based techniques have been employed to obtain solvated ions from the NP solution, but this approach leads to NP agglomeration, making further toxicological analysis difficult to assess. Additionally, extremely small NPs are retained in the supernatant even after ultracentrifugation, leading to incomplete separation of ions from their respective NPs. To address these complex toxicology issues we applied enhanced separation techniques with the aim to study levels of ions originating from the Ag-NP using separation by a recirculating tangential flow filtration system. This system uses a unique diffusion-driven filtration method that retains large particles within the continuous flow path, while allowing the solution (ions) to pass through molecular filters by lateral diffusion separation. Use of this technique provides reproducible NP separation from their solvated ions which permits for further quantification using an inductively coupled plasma mass spectrometry or comparison use in bioassay exposures to biological systems. In this study, we thoroughly characterised NPs in biologically relevant solutions to understand the dissolution of Ag-NPs (10 and 50 nm) over time. Our results suggest that the ion dissolution from Ag-NPs is dependent on parameters such as exposure time, chemical composition and temperature of the exposure solution. Further, the well-characterised separated ionic and NP solutions were exposed to a lung epithelial cell line (A549) to evaluate the toxicity of each fraction. Results suggest that although Ag-NPs (unseparated) show concentration-dependent toxicity, dissolution of ions appears to exacerbate the toxicological effect. This finding adds data to the set of probable toxic exposure mechanisms elicited by metallic nanomaterials and provides important consideration when assessing findings of key cell function modulation.
Nanotoxicology.Nanotoxicology.2014 Nov;8:718-27. doi: 10.3109/17435390.2013.824127. Epub 2013 Aug 1.
Abstract In the field of toxicology of nanomaterials, scientists have not clearly determined if the observed toxicological events are due to the nanoparticles (NPs) themselves or the dissolution of ions released into the biophysiological environment or both phenomenon participate in combination base
PMID 23848466

Using gold nanorods core/silver shell nanostructures as model material to probe biodistribution and toxic effects of silver nanoparticles in mice.

Meng J, Ji Y, Liu J, Cheng X, Guo H, Zhang W, Wu X, Xu H.Author information Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College , Beijing , P. R. China.AbstractAbstract The aim of this work was to probe the biodistribution and toxic effects of silver nanoparticles (NPs) with powerful anti-bacterial and anti-virus activities. For this purpose, novel silver NPs with gold nanorod (NR) core and silver shell (Au@Ag NRs) were developed and employed as a model material. The inner gold core provided an excellent internal reference for tracking the NRs in vivo. After subcutaneous injection of Au@Ag NRs, silver and gold contents in the subcutis and organs were examined by inductively coupled plasma mass spectrometry at different time points within 28 days. Histological analysis, physiological function and complement faction 3 (C3) and 5a (C5a) measurement were performed over time to reveal the toxic effect of Au@Ag NRs in vivo. Experimental results showed that majority of the Au@Ag NRs remained in the injection site except for a small amount migrating into the lymph nodes. The silver shell was dissolved in the subcutaneous tissue and released silver ions rapidly, which resulted in detectable silver accumulation in most of the organs. The accumulated silver ions in the kidney not only interacted with the kidney cells membrane but also induced a rapid increase of complement fraction C3 followed by a significant consumption and C3a and C5a production significantly in the serum, which resulted in kidney oxidative damage and eventually led to the morphological changes and filtration function impairment of the glomerulus. The released silver ions also caused oxidative injury of subcutaneous tissue in the injection site.
Nanotoxicology.Nanotoxicology.2014 Sep;8:686-96. doi: 10.3109/17435390.2013.822593. Epub 2013 Jul 29.
Abstract The aim of this work was to probe the biodistribution and toxic effects of silver nanoparticles (NPs) with powerful anti-bacterial and anti-virus activities. For this purpose, novel silver NPs with gold nanorod (NR) core and silver shell (Au@Ag NRs) were developed and employed as a model ma
PMID 23837638

Oral, short-term exposure to titanium dioxide nanoparticles in Sprague-Dawley rat: focus on reproductive and endocrine systems and spleen.

Tassinari R, Cubadda F, Moracci G, Aureli F, D'Amato M, Valeri M, De Berardis B, Raggi A, Mantovani A, Passeri D, Rossi M, Maranghi F.Author information Istituto Superiore di Sanità , Rome , Italy.AbstractAbstract The study explored possible reproductive and endocrine effects of short-term (5 days) oral exposure to anatase TiO2 nanoparticles (0, 1, 2 mg/kg body weight per day) in rat. Nanoparticles were characterised by scanning electron microscopy (SEM) and transmission electron microscopy, and their presence in spleen, a target organ for bioaccumulation, was investigated by single-particle inductively coupled plasma mass spectrometry and SEM/energy-dispersive X-ray. Analyses included serum hormone levels (testosterone, 17-β-estradiol and triiodothyronine) and histopathology of thyroid, adrenals, ovary, uterus, testis and spleen. Increased total Ti tissue levels were found in spleen and ovaries. Sex-related histological alterations were observed at both dose levels in thyroid, adrenal medulla, adrenal cortex (females) and ovarian granulosa, without general toxicity. Altered thyroid function was indicated by reduced T3 (males). Testosterone levels increased in high-dose males and decreased in females. In the spleen of treated animals TiO2 aggregates and increased white pulp (high-dose females) were detected, even though Ti tissue levels remained low reflecting the low doses and the short exposure time. Our findings prompt to comprehensively assess endocrine and reproductive effects in the safety evaluation of nanomaterials.
Nanotoxicology.Nanotoxicology.2014 Sep;8:654-62. doi: 10.3109/17435390.2013.822114. Epub 2013 Jul 25.
Abstract The study explored possible reproductive and endocrine effects of short-term (5 days) oral exposure to anatase TiO2 nanoparticles (0, 1, 2 mg/kg body weight per day) in rat. Nanoparticles were characterised by scanning electron microscopy (SEM) and transmission electron microscopy, and thei
PMID 23834344

Japanese Journal

強い内皮依存性血管弛緩作用をもつ新たな赤ワインポリフェノールの特性

山崎理美,岩田宏紀,村田恵理,片野由美,石幡明
山形大学紀要. 医学 : 山形医学 29(2), 45-56, 2011-08-15
【背景】赤ワインに含まれる多種類のポリフェノール化合物(RWPCs)は強い血管弛緩作用を有する。RWPCs中の血管弛緩作用を有するポリフェノールはいくつか報告されているが、RWPCsにはそれら以外にも未知の成分が多数存在することが知られている。本研究では、血管弛緩作用を有する新たな赤ワインポリフェノールを探索し、その特性を検討することを目的に、RWPCsの比較的親水性の高い成分を分離・分画 …
NAID 110008614765

Breaking Tri-Bimaximal Mixing and Large θ_<13>(Particles and Fields)

SHIMIZU Yusuke,TANIMOTO Morimitsu,WATANABE Atsushi
理論物理学の進歩 126(1), 81-90, 2011-07-25
… We discuss breaking the tri-bimaximal mixing by adding a simple mass matrix, which could be derived from some non-Abelian discrete symmetries. … It is found that sinθ_<13>=0.1-0.2 is expected in our model independent analysis of the generalized mass matrix for the normal or inverted hierarchical neutrino mass spectrum. …
NAID 110008712967

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★リンクテーブル★

リンク元	「質量分析」「mass spectroscopy」「mass spectrometric」「質量スペクトル分析」
関連記事	「analysis」「spectrum」「mass」「mass spectrum」