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1.
Maw-Rong Lee Sue-Tsing Liou Ru-Jen Cheng 《Journal of the American Society for Mass Spectrometry》1997,8(1):62-67
Mass spectra of meso-phenyl-substituted tetrabenzoporphyrins were investigated by fast-atom bombardment mass spectrometry and tandem mass spectrometry. A cluster of adduct ions with mass-to-charge ratio values higher than the corresponding molecular ions of the porphyrins has been observed. The mass number differences among the series of cluster ions are constant depending on the para-phenyl substituents. Under certain conditions, dimers or trimers of molecular ions with low abundances have been detected. To trace the origin of the adduct ions, a series of experiments based on mass spectrometry have been carried out. The mass spectrum of tetrabenzoporphyrin showed no adduct ions with mass number differences of 90 even with the addition of phenylacetic acid. The mass spectrum of meso-tetraphenylte-trabenzoporphyrin 13C-labeled at the meso carbons showed adduct ions with mass number differences of 91. Product spectra of [2M + H]+ or [3M + H]+ of porphyrins exhibited adduct ions. All these results suggest that fragmentations of [2M + H]+ or [3M + H]+ may be one of the many possible routes to form the adduct ions, and the mass number differences among the series of these cluster ions should correspond to the benzyl group from the meso positions of meso-phenyl-substituted tetrabenzoporphyrins. 相似文献
2.
Angelo Liguori Loredana Maiuolo Antonio De Nino Antonio Procopio Giovanni Sindona 《Journal of the American Society for Mass Spectrometry》1999,10(10):975-982
Rules for the gas-phase fragmentation mechanism of the negative ions of lipophilic phosphotriester molecules of biological interest have been established by fast-atom bombardment mass spectrometry/mass spectrometry. The mass-analyzed ion kinetic energy spectra of the [M ? H]? of dinucleoside (1–4) and nucleoside glucopyranoside (5–9) phosphotriesters show that in the absence of charges on the phosphate bridge, the availability of acidic protons on the 5′-end nucleobase drives a preferred reaction path which leads to 5′-O-nucleotide or 6-O-glucopyranoside monophosphate anions. 相似文献
3.
Mitsuo Takayama 《Journal of the American Society for Mass Spectrometry》1995,6(2):114-119
Japan The mechanism for the formation of molecular ions M+· under fast-atom bombardment (FAB) conditions with a liquid matrix is discussed on the basis of the mass spectra of pyrene, coronene, and fullerene C60 obtained by using electron impact, gas-phase fast-atom bombardment, and gas-phase fast-molecule bombardment techniques. The obtained results suggest that formation of the M+· ions under FAB conditions is not due to direct collisions between analytes M and fast atoms A, but is due to collision interactions between M and recoiling matrix molecules B or matrix ions. It has been confirmed, furthermore, that the FAB conditions with a liquid matrix are sufficient in energy for formation of singly charged ions M+· and insufficient for the formation of multiply charged ions M z+ (z=2, 3) of pyrene, coronene, and C60. 相似文献
4.
A new technique using negative-ion fast atom bombardment mass spectrometry for the analysis of xanthates and related compounds is described. Electron impact and positive-ion fast atom bombardment mass spectrometry produced no structurally related fragment ions or observable molecular ions at the expected m/z values. It was demonstrated that negative-ion fast atom bombardment ionization was the most suitable method of ionization for structure elucidation studies for the compounds described. 相似文献
5.
Kathleen A. Kayganich-Harrison Robert C. Murphy 《Journal of the American Society for Mass Spectrometry》1994,5(3):144-150
A method employing stable isotope labeling and fast-atom bombardment (FAB) tandem mass spectrometry has been developed to directly assess events of biosynthesis and metabolism of arachidonic acid containing phospholipid molecular species by cells carried in culture. Mast cells, cultured with [13C]linoleic acid, converted this precursor into arachidonic acid which was then incorporated into cellular phospholipids. Over a 24 hour period, the extent of label enrichment in each arachidonate-containing phospholipid molecular species was monitored by using negative FAB ionization with selected reaction monitoring. Specific incorporation of [13C17] labeled arachidonate was determined from the ratio of the carboxylate anions at m/z 320 and 303, which correspond to [13C17]arachidonate and unlabeled arachidonate, respectively, produced by collision-induced dissociation of each specific molecular anion. The use of [13C]linoleic acid as a precursor of arachidonic acid avoids the problem of changing the endogenous pool size by directly adding labeled arachidonic acid. Measurement of the [13C17]label also avoids interferences from endogenous isobaric fatty acids that are naturally present at low levels. 相似文献
6.
Fast atom bombardment mass spectrometry (FAB-MS) is applied to distinguish N-terminal series ions from C-terminal series ions of a peptide by on-probe acetylation, it providesvaluable information about the sequence of an unknown peptide. The FAB mass spectra containa number of characteristic ions at low-mass region in addition to the sequence ions at high-massregion. It was found that the ions below m/z 200 are characteristic of the amino acid composition ofthe peptide, from which the amino acid composition of the peptide could be estimated. Additionally,mixture analysis is also discussed. 相似文献
7.
Vincent Stroobant Edmond de Hoffmann Raymond Libert François Van Hoof 《Journal of the American Society for Mass Spectrometry》1995,6(7):588-596
Fragmentation of negative ions produced by fast-atom bombardment (FAB) from 14 tauroconjugated bile acids and some of their deuterated analogs has been studied by mass spectrometry and by collision-induced dissociation (CED) tandem mass spectrometry at low energy. Low energy collision-induced dissociation of the deprotonated molecules [M - H]? of these tauroconjugated bile acids leads to both charge-driven and charge-remote fragmentations (CRF). The former yields neutral loss from the side chain with charge migration during the fragmentation process. These fragments dominate the CID spectra, but are absent from the FAB spectra. Their relative abundances are dependent on the number and the positions of the hydroxyl groups in the steroid nucleus and thus permit distinction among some positional isomers. The CRF fragments correspond to cleavages in the side chain up to fragmentations across the steroid rings with charge retention on the sulfonate group. These CRF fragments, which also are useful for structural identification, are less intense in CID than in FAB spectra. It appears that these charge-remote fragments are favored by unsaturation in the steroid rings, either as keto groups or as endocyclic double bonds. Tandem mass spectrometry combined with the use of deuterated analogs demonstrates that the structures of the survivor pseudomolecular ions and of the CRF fragments are not rearranged. 相似文献
8.
Lambert Ngoka Carlito B. Lebrilla 《Journal of the American Society for Mass Spectrometry》1993,4(3):210-215
Unimolecular metastable decomposition of cucyclodextrin cations is observed in a fast-atom bombardment Fourier transform mass spectrometry instrument. Cleavage reactions occur at the glycosidic bonds to produce oligomeric fragment ions. The first-order rate constant for the decay of the protonated parent was measured and found to be (4.2 ± 1.0) × 102s?1. 相似文献
9.
Christopher M. Benton Chang Kee Lim Caje Moniz Donald J. L. Jones 《Biomedical chromatography : BMC》2013,27(12):1782-1787
Biological and clinical samples for porphyrin and porphyrinogen analyses by liquid chromatography–tandem mass spectrometry (LC‐MS/MS) are often contaminated with poly(ethylene)glycol (PEG), which complicates the interpretation of mass spectra and characterisation of new porphyrin metabolites. Two contaminating PEG molecules (m/z 833 and m/z 835) were completely separated from uroporphyrin I (m/z 831) by travelling wave ion mobility spectrometry and characterised by tandem mass spectrometry. One of the PEG species (m/z 835) also co‐eluted with uroporphyrinogen I (m/z 837) and was unresolvable by travelling wave ion mobility spectrometry/MS, therefore contaminating the MS/MS mass spectra owing to isotope distribution. These PEG species, with the [M + H]+ ions at m/z at 833 and/or m/z 835, co‐eluted with uroporphyrin I and uroporphyrinogen I by LC‐MS/MS and could be wrongly identified as uroporphomethenes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
10.
Carl F. Ijames Charles L. Wilkins 《Journal of the American Society for Mass Spectrometry》1990,1(3):208-216
A differentially pumped external secondary ion source for Fourier transform mass spectrometry is described. Installation does not interfere with other experiments such as laser desorption or photodissociation. Spectra of cesium iodide clusters (with ions up to m/z 8187), polyethylene glycol 1000, and histidine from both glycerol and dithiothreitol-dithioerythritol matrices are reported. The ion with m/z 156 from histidine was recorded with mass resolution of 160,000. 相似文献
11.
Gerardo M. Caballero Eduardo G. Gros Osvaldo Teme Centurión Lydia R. Galagovsky 《Journal of the American Society for Mass Spectrometry》1997,8(3):270-274
Positive ion fast-atom bombardment mass spectra of brassinosteroid analogs have been systematically obtained for the first time. The spectra of six brassinosteroid analogs and their corresponding 22S,23S isomers included the protonated molecule in medium to high relative intensity. The fragmentation pattern is dominated by side chain cleavage. There is a marked preferential loss of acetic acid from the [M + H]+ ion of 5α-hydrogen-3β-acetylated derivatives compared to the 5α-hydroxy-3β-acetylated analogs. 相似文献
12.
Jürgen H. Gross 《Analytical and bioanalytical chemistry》2013,405(26):8663-8668
Direct analysis in real-time mass spectrometry (DART-MS) is normally applied for small-molecule analysis up to about m/z 1,000. Here, for the analysis of polydimethylsiloxanes, high-mass capabilities expanding beyond m/z 3,000 are demonstrated. In addition, polydimethylsiloxanes provide an ideal mass calibration standard for positive-ion DART-MS. A mass reference list has been compiled to cover ions from m/z 200 up to m/z 2,600. Species with more than 20 silicon atoms exhibit increasingly broader isotopic patterns with decreasing abundances of the monoisotopic ions. The use of the first isotopic peaks for analyte ions above m/z 2,000 serves as a work-around and ensures easy and reproducible recognition of the reference peaks by the instrument data system. Here, the positive-ion DART mass spectra of polydimethylsiloxanes and the corresponding experimental procedures are described, and the mass reference list is provided. 相似文献
13.
Hsu FF Turk J Stewart ME Downing DT 《Journal of the American Society for Mass Spectrometry》2002,13(6):680-695
We applied electrospray ionization (ESI) tandem quadrupole mass spectrometry to establish the fragmentation pathways of ceramides under low energy collisional-activated dissociation (CAD) by studying more than thirty compounds in nine subclasses. The product-ion spectra of the [M + Li]+ ions of ceramides contain abundant fragment ions that identify the fatty acyl substituent and the long-chain base (LCB) of the molecules, and thus, the structure of ceramides can be easily determined. Fragment ions specific to each ceramide subclasses are also observed. These feature ions permit differentiation among different ceramide subclasses. The ion series arising from the classical C-C bond cleavages that were reported in the fast-atom bombardment (FAB)-high energy tandem mass spectrometry is not observable; however, the product-ion spectra contain multiple fragment ions informative for structural characterization and isomer identification. We also investigated the tandem mass spectra of the fragment ions generated by in-source CAD (pseudo-MS3) and of the deuterium-labeling molecular species obtained by H/D exchange to support the ion structure assignments and the proposed fragmentation pathways that lead to the ion formation. 相似文献
14.
Michael J. Huddleston Roland S. Annan Mark F. Bean Steven A. Carr 《Journal of the American Society for Mass Spectrometry》1993,4(9):710-717
A mass spectrometry-based method that does not involve the use of radiolabeling was developed for selective detection of phosphopeptides in complex mixtures. Mixtures of phosphorylated and nonphosphorylated peptides at the low picomole level are analyzed by negative ion electrospray liquid chromatography/mass spectrometry using C-18 packed fused-silica columns (≤320-μm i.d.). Peptides and phosphopeptides in the chromatographic eluant undergo collision-induced dissociation in the free-jet expansion region prior to the mass analyzing quadrupole. Using relatively high collisional excitation potentials, phospho|peptides containing phosphoserine, phosphothreonine, and phosphotyrosine fragment to yield diagnostic ions at m/z 63 and 79 corresponding to PO2 ?; and PO3 ?, respectively. Chromatographic peaks containing phosphopeptides are indicated where these diagnostic ions maximize. The highest sensitivity for phosphopeptide detection is obtained using selected-ion monitoring for m/z 63 and 79. Full-scan mass spectra that exhibit the diagnostic phosphopeptide fragment ions, together with pseudomolecular ions, may be obtained by stepping the collisional excitation potential from a high value during the portion of each scan in which the low-mass-to-charge ratio diagnostic marker ions are being detected to a lower value while the upper mass-to-charge ratio range is being scanned. Good sensitivity for phosphopeptide detection was achieved using standard trifluoroacetic acid containing mobile phases for reversed-phase high-performance liquid chromatography. Data illustrating the selectivity and sensitivity of the approach are presented for mixtures of peptides and phosphopeptides containing the three commonly phosphorylated amino acids. 相似文献
15.
Zhaohui Du Terry N. Olney D. J. Douglas 《Journal of the American Society for Mass Spectrometry》1997,8(12):1230-1236
An inductively coupled plasma mass spectrometer system is described in which the quadrupole mass filter is operated in the third stability region with Mathieu parameters (a, q)=(3, 3). Operation at the upper tip of this region is found to give generally better sensitivity and resolution than operation at the lower tip. A limiting resolution at half height of 4000 at m/z 59 is possible with operation at the upper tip. This resolution is insufficient to separate atomic ions from molecular ions of the same nominal mass except in favorable cases. However, operation at moderate resolution (R 1/2=500 to 1000) is found to give very high abundance sensitivity (>107). The results suggest that the third stability region may be advantageous for specialized applications of inductively coupled plasma mass spectrometry. 相似文献
16.
Roger Guevremont Randy W. Purves 《Journal of the American Society for Mass Spectrometry》1999,10(6):492-501
High field asymmetric waveform ion mobility spectrometry (FAIMS) provides atmospheric pressure, room temperature, low-resolution separation of gas-phase ions. The FAIMS analyzer acts as an ion filter that can continuously transmit one type of ion, independent of m/z. The combination of FAIMS with electrospray ionization and mass spectrometry (ESI-FAIMS-MS) is a powerful technique and is used in this study to investigate the cluster ions of leucine enkephalin (YGGFL). Separation by FAIMS of leucine enkephalin ions having the same m/z (m/z 556.5), [M + H]+ and [2M + 2H]2+, was observed. In addition, four complex ions of leucine enkephalin, [2M + H]+, [4M + 2H]2+, [6M + 3H]3+, and [8M + 4H]4+, all having m/z 1112, were shown to be separated in FAIMS. Fragmentation of ions as the result of harsh conditions within the mass spectrometer interface (FAIMS-MS) was shown to provide similar information to that obtained from MS/MS experiments in conventional ESI-MS. 相似文献
17.
L. P. Brüll W. Heerma J. Thomas-Oates J. Haverkamp V. Kovácik P. Kovác 《Journal of the American Society for Mass Spectrometry》1997,8(1):43-49
The fragmentation behavior of [M + H]+ ions of a series of underivatized and per-O-methylated trisaccharides having 1 → 6 linked residues, of which one or two is a deoxy-fluoro or deoxy residue and thus has a unique mass, has been studied by using collision-induced dissociation fast-atom bombardment mass spectrometry. In addition to the usual fragment ions resulting from glycosidic bond cleavage, fragment ions were observed which must have been generated following an unusual rearrangement process which can be rationalized in terms of the loss of an internal monosaccharide residue. 相似文献
18.
Wisut Wichitnithad Terence J. McManus Patrick S. Callery 《Rapid communications in mass spectrometry : RCM》2010,24(17):2547-2553
Isobaric product ions cannot be differentiated by exact mass determinations, although in some cases deuterium labeling can provide useful structural information for identifying isobaric ions. Proposed fragmentation pathways of fentanyl were investigated by electrospray ionization ion trap mass spectrometry coupled with deuterium labeling experiments and spectra of regiospecific deuterium labeled analogs. The major product ion of fentanyl under tandem mass spectrometry (MS/MS) conditions (m/z 188) was accounted for by a neutral loss of N‐phenylpropanamide. 1‐(2‐Phenylethyl)‐1,2,3,6‐tetrahydropyridine (1) was proposed as the structure of the product ion. However, further fragmentation (MS3) of the fentanyl m/z 188 ion gave product ions that were different from the product ion in the MS/MS fragmentation of synthesized 1, suggesting that the m/z 188 product ion from fentanyl includes an isobaric structure different from the structure of 1. MS/MS fragmentation of fentanyl in deuterium oxide moved one of the isobars to 1 Da higher mass, and left the other isobar unchanged in mass. Multistage mass spectral data from deuterium‐labeled proposed isobaric structures provided support for two fragmentation pathways. The results illustrate the utility of multistage mass spectrometry and deuterium labeling in structural assignment of isobaric product ions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
Lara Fornai Annalisa Angelini Ivo Klinkert Frans Giskes Andras Kiss Gert Eijkel Erika A. Amstalden-van Hove Leendert A. Klerk Marny Fedrigo Giuseppe Pieraccini Gloriano Moneti Marialuisa Valente Gaetano Thiene Ron M. A. Heeren 《Analytical and bioanalytical chemistry》2012,404(10):2927-2938
Cardiovascular diseases are the world’s number one cause of death, accounting for 17.1 million deaths a year. New high-resolution molecular and structural imaging strategies are needed to understand underlying pathophysiological mechanism. The aim of our study is (1) to provide a molecular basis of the heart animal model through the local identification of biomolecules by mass spectrometry imaging (MSI) (three-dimensional (3D) molecular reconstruction), (2) to perform a cross-species validation of secondary ion mass spectrometry (SIMS)-based cardiovascular molecular imaging, and (3) to demonstrate potential clinical relevance by the application of this innovative methodology to human heart specimens. We investigated a MSI approach using SIMS on the major areas of a rat and mouse heart: the pericardium, the myocardium, the endocardium, valves, and the great vessels. While several structures of the heart can be observed in individual two-dimensional sections analyzed by metal-assisted SIMS imaging, a full view of these structures in the total heart volume can be achieved only through the construction of the 3D heart model. The images of 3D reconstruction of the rat heart show a highly complementary localization between Na+, K+, and two ions at m/z 145 and 667. Principal component analysis of the MSI data clearly identified different morphology of the heart by their distinct correlated molecular signatures. The results reported here represent the first 3D molecular reconstruction of rat heart by SIMS imaging. Figure
Workflow of the 3D reconstruction. A Tissue section, B gold deposition is done by sputter coating, C, C1 SIMS-ToF mass analyzer, C, C2 mass spectral peaks, C, C3 datacube images; D, E Reconstruction of the heart showing 3D-spatial distributions of three different ions 145 m/z (red), 23 m/z (green), and 39 m/z (blue); F coregistration of 40 individual MS imaging 相似文献
20.
Loreen C. Zeller John T. Farrell Hilkka I. Kenttämaa Tuula Kuivalainen 《Journal of the American Society for Mass Spectrometry》1993,4(2):125-134
Multiple-stage mass spectrometry involving consecutive collision-activated dissociation reactions was used to examine the structures of fragment ions commonly formed on electron ionization of organophosphorus esters. The compounds studied include several aryl thiophosphates, some of which are analogs of common pesticides. Energy-resolved collisionactivated dissociation experiments allow the dissociation of the molecular ions of these compounds in such a manner that only a few fragment ions dominate the spectrum. An abundant fragment ion of m/z 109, formed from all of the compounds studied, can have at least four different stable structures: (CH3O)2PO+, CH3CH2OP(O)OH+, CH2 =CHOP(H)(OH)2 +, and (CH2O)2P(H)OH+. The structure of the fragment ion of m/z 109 was found to reflect the phosphorus-containing part of the compounds studied. Another abundant fragment ion obtained for all the aryl esters studied is structurally characteristic of the aromatic moiety of the molecule. This fragment ion is the result of a complex rearrangement involving transfer of an alkylene group to the aromatic ring from the phosphoruscontaining part of the molecular ion. The utility of these fragment ions in the structural characterization of unknown organophosphorus esters is discussed. 相似文献