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177 results on '"Caprioli, R. M."'

1. Spatial mapping of protein composition and tissue organization : a primer for multiplexed antibody-based imaging

Author

Hickey, J. W., Neumann, E. K., Radtke, A. J., Camarillo, J. M., Beuschel, R. T., Albanese, A., McDonough, E., Hatler, J., Wiblin, A. E., Fisher, J., Croteau, J., Small, E. C., Sood, A., Caprioli, R. M., Angelo, R. M., Nolan, G. P., Chung, K., Hewitt, S. M., Germain, R. N., Spraggins, J. M., Lundberg, Emma, Snyder, M. P., Kelleher, N. L., Saka, S. K., Hickey, J. W., Neumann, E. K., Radtke, A. J., Camarillo, J. M., Beuschel, R. T., Albanese, A., McDonough, E., Hatler, J., Wiblin, A. E., Fisher, J., Croteau, J., Small, E. C., Sood, A., Caprioli, R. M., Angelo, R. M., Nolan, G. P., Chung, K., Hewitt, S. M., Germain, R. N., Spraggins, J. M., Lundberg, Emma, Snyder, M. P., Kelleher, N. L., and Saka, S. K.

Abstract

Tissues and organs are composed of distinct cell types that must operate in concert to perform physiological functions. Efforts to create high-dimensional biomarker catalogs of these cells have been largely based on single-cell sequencing approaches, which lack the spatial context required to understand critical cellular communication and correlated structural organization. To probe in situ biology with sufficient depth, several multiplexed protein imaging methods have been recently developed. Though these technologies differ in strategy and mode of immunolabeling and detection tags, they commonly utilize antibodies directed against protein biomarkers to provide detailed spatial and functional maps of complex tissues. As these promising antibody-based multiplexing approaches become more widely adopted, new frameworks and considerations are critical for training future users, generating molecular tools, validating antibody panels, and harmonizing datasets. In this Perspective, we provide essential resources, key considerations for obtaining robust and reproducible imaging data, and specialized knowledge from domain experts and technology developers., QC 20220608

Published
2022
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7. Activation of heme biosynthesis by a small molecule that is toxic to fermenting Staphylococcus aureus

Author

Skaar, E. P., Reid, P. R., Kehl-Fie, T. E., DuBois, J. L., Mike, L. A., Aranmolate, O., Caprioli, R. M., Stauff, D. L., Vitko, N. P., Sullivan, S., Richardson, A. R., Dutter, B. F., Moore, J. L., and Sulikowski, G. A.

Abstract

Staphylococcus aureus is a significant infectious threat to global public health. Acquisition or synthesis of heme is required for S. aureus to capture energy through respiration, but an excess of this critical cofactor is toxic to bacteria. S. aureus employs the heme sensor system (HssRS) to overcome heme toxicity; however, the mechanism of heme sensing is not defined. Here, we describe the identification of a small molecule activator of HssRS that induces endogenous heme biosynthesis by perturbing central metabolism. This molecule is toxic to fermenting S. aureus, including clinically relevant small colony variants. The utility of targeting fermenting bacteria is exemplified by the fact that this compound prevents the emergence of antibiotic resistance, enhances phagocyte killing, and reduces S. aureus pathogenesis. Not only is this small molecule a powerful tool for studying bacterial heme biosynthesis and central metabolism; it also establishes targeting of fermentation as a viable antibacterial strategy.

Published
2013
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8. Variations in the expressed antimicrobial peptide repertoire of northern leopard frog (Rana pipiens) populations suggest intraspecies differences in resistance to pathogens

Author

Tennessen, J A, Woodhams, D C, Chaurand, P, Reinert, L K, Billheimer, D, Shyr, Y, Caprioli, R M, Blouin, M S, Rollins-Smith, L A, University of Zurich, and Rollins-Smith, L A

Subjects
2403 Immunology, Temporin, Mass spectrometry, Rana pipiens, Lithobates, Rana palustris, Aeromonas hydrophila, 1309 Developmental Biology, 10127 Institute of Evolutionary Biology and Environmental Studies, Staphylococcus epidermidis, 570 Life sciences, biology, 590 Animals (Zoology), Antimicrobial peptides, Brevinin, Peptidomics, Batrachochytrium dendrobatidis, Ranatuerin
Published
2009
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12. Posters * Endometriosis, Endometrium and Implantation

Author

Jiang, Y., primary, Zhao, J., additional, Hua, M., additional, Zhen, X., additional, Yan, G., additional, Hu, Y., additional, Sun, H., additional, Selvaggi, L., additional, Zannoni, G. F., additional, Tagliaferri, V., additional, De Cicco, S., additional, Vellone, V. G., additional, Romualdi, D., additional, Lanzone, A., additional, Guido, M., additional, Fassbender, A., additional, Vodolazkaia, A. V., additional, Bossuyt, X. B., additional, Kyama, M. K., additional, Meuleman, C. M., additional, Peeraer, K. P., additional, Tomassetti, C. T., additional, D'Hooghe, T. M., additional, Lumini, A., additional, Nanni, L., additional, Manna, C., additional, Pappalardo, S., additional, Melin, A., additional, Lundholm, C., additional, Malki, N., additional, Swahn, M. L., additional, Sparen, P., additional, Bergqvist, A., additional, Crescenzi, F., additional, Farrag, A., additional, Sallam, H. N., additional, Zou, L., additional, Ding, G., additional, Zhang, R., additional, Sheng, J., additional, Huang, H., additional, von Kleinsorgen, C., additional, Wilson, T., additional, Thiel-Moder, U., additional, Ebert, A. D., additional, Reinfandt, M., additional, Papadopolous, T., additional, Melo, A. S., additional, Rodrigues, J. K., additional, Dib, L. A., additional, Andrade, A. Z., additional, Donabela, F. C., additional, Ferriani, R. A., additional, Navarro, P. A., additional, Tocci, A., additional, Royo, P., additional, Lucchini, C., additional, Ramos, P., additional, Alcazar, J. L., additional, Habara, T., additional, Terada, S., additional, Yoshioka, N., additional, Hayashi, N., additional, Haouzi, D., additional, Assou, S., additional, Monzo, C., additional, Anahory, T., additional, Dechaud, H., additional, De Vos, J., additional, Hamamah, S., additional, Gonzalez-Ramos, R., additional, Rojas, C., additional, Rocco, J., additional, Poch, A., additional, Sovino, H., additional, Kohen, P., additional, Munoz, A., additional, Devoto, L., additional, Aygen, M. A., additional, Atakul, T., additional, Oner, G., additional, Ozgun, M. T., additional, Sahin, Y., additional, Ozturk, F., additional, Li, R., additional, Qiao, J., additional, Zhylkova, I., additional, Feskov, A., additional, Feskova, I., additional, Somova, O., additional, Chumakova, N., additional, Bontekoe, S., additional, Blake, D., additional, Heineman, M. J., additional, Williams, E. C., additional, Johnson, N. P., additional, Motta, A., additional, Colaci, D., additional, Horton, M., additional, Faut, M., additional, Bisioli, C., additional, Kopcow, L., additional, de Zuniga, I., additional, Wiener-Megnazi, Z., additional, Khaytov, M., additional, Lahav - Baratz, S., additional, Shiloh, H., additional, Koifman, M., additional, Oslander, R., additional, Dirnfeld, M., additional, Sundqvist, J., additional, Andersson, K. L., additional, Scarselli, G., additional, Gemzell-Danielsson, K., additional, Lalitkumar, P. G. L., additional, Tokushige, N., additional, Markham, R., additional, Crossett, B., additional, Ahn, S., additional, Nelaturi, V., additional, Khan, A., additional, Fraser, I. S., additional, Van Vaerenbergh, I., additional, Fatemi, H. M., additional, Blockeel, C., additional, Van Lommel, L., additional, In't Veld, P., additional, Schuit, F., additional, Kolibianakis, E. M., additional, Devroey, P., additional, Bourgain, C., additional, Sugino, N., additional, Tamura, I., additional, Lee, R., additional, Maekawa, R., additional, Gelbaya, T., additional, Gordts, S., additional, D'Hooghe, T. N., additional, Gergolet, M., additional, Nardo, L. G., additional, Yu, H., additional, Wang, H., additional, Lee, C., additional, Soong, Y., additional, Kremenska, Y., additional, Masliy, Y., additional, Goncharova, Y., additional, Kremenskoy, M., additional, Veselovskyy, V., additional, Zukin, V., additional, Sudoma, I., additional, Delgado-Rosas, F., additional, Gomez, R., additional, Tamarit, S., additional, Abad, A., additional, Simon, C., additional, Pellicer, A., additional, Racicot, M., additional, Dean, N. L., additional, Antaki, R., additional, Menard, S., additional, Kadoch, I. J., additional, Garcia-Guzman, R., additional, Cabrera Romero, L., additional, Hernandez, J., additional, Palumbo, A., additional, Marshall, E., additional, Lowry, J., additional, Maybin, J. A., additional, Collins, F., additional, Critchley, H. O. D., additional, Saunders, P. T. K., additional, Chaudhury, K., additional, Jana, S. K., additional, Banerjee, P., additional, Mukherjee, S., additional, Chakravarty, B. N., additional, Allegra, A., additional, Marino, A., additional, Lama, A., additional, Santoro, A., additional, Agueli, C., additional, Mazzola, S., additional, Volpes, A., additional, Delvoux, B., additional, de Graaff, A. A., additional, Kyama, C. M., additional, Dunselman, G. A. J., additional, Romano, A., additional, Caccavo, D., additional, Pellegrino, N. M., additional, Totaro, I., additional, Panzarino, M., additional, Nardelli, C., additional, Depalo, R., additional, Flores, R., additional, Montanana, V., additional, Monzo, A., additional, Polo, P., additional, Garcia-Gimeno, T., additional, Cabo, A., additional, Rubio, J. M., additional, Beets, G. L., additional, van Lankveld, J. J., additional, Kim, H. Y., additional, Lee, B. S., additional, Cho, S. H., additional, Choi, Y. S., additional, Seo, S. K., additional, Lee, K. E., additional, Yang, H. I., additional, Abubakirov, A., additional, Vacheyshvili, T., additional, Krechetova, L., additional, Ziganshina, M., additional, Demura, T., additional, Nazarenko, T., additional, Fulop, I., additional, Rucz, A., additional, Herczegh, S. Z., additional, Ujvari, A., additional, Takacs, S. Z., additional, Szakonyi, T., additional, Lopez - Muniz, A., additional, Zamora, L., additional, Serra, O., additional, Guix, C., additional, Lopez-Teijon, M., additional, Benadiva, C., additional, Alvarez, J. G., additional, Goudakou, M., additional, Karkanaki, A., additional, Kalogeraki, A., additional, Mataliotakis, I., additional, Kalogiannidis, I., additional, Prapas, I., additional, Hosie, M., additional, Thomson, K. J., additional, Penny, C. B., additional, Penny, C., additional, Hosie, M. J., additional, McKinnon, B., additional, Klaeser, B., additional, Bersinger, N., additional, Mueller, M. D., additional, Horcajadas, J. A., additional, Martinez-Conejero, J. A., additional, Montesinos, M., additional, Morgan, M., additional, Fortuno, S., additional, Yi, K. W., additional, Shin, J. H., additional, Park, H. T., additional, Kim, T., additional, Kim, S. H., additional, Hur, J. Y., additional, Chan, R. W. S., additional, Chan, Y. Y., additional, Ng, E. H. Y., additional, Yeung, W. S. B., additional, Santulli, P., additional, Borghese, B., additional, Chopin, N., additional, Marcellin, L., additional, de Ziegler, D., additional, Chapron, C., additional, Elnashar, A., additional, Badawy, A., additional, Mosbah, A., additional, Tzioras, S., additional, Polyzos, N. P., additional, Messini, C. I., additional, Papanikolaou, E. G., additional, Valachis, A., additional, Patavoukas, E., additional, Mauri, D., additional, Messinis, I. E., additional, Acar, N., additional, Hirota, Y., additional, Tranguch, S., additional, Daikoku, T., additional, Burnum, K. E., additional, Xie, H., additional, Kodama, A., additional, Osuga, Y., additional, Ustunel, I., additional, Friedman, D. B., additional, Caprioli, R. M., additional, Dey, S. K., additional, Mitra, A., additional, Sahu, R., additional, Pal, M., additional, Bhattachrayya, A. K., additional, Bhattachrya, J., additional, Ferrero, S., additional, Remorgida, V., additional, Rollandi, G. A., additional, Biscaldi, E., additional, Cho, S., additional, Arena, E., additional, Morando, A., additional, Tomazevic, T., additional, Ban-Frangez, H., additional, Virant-Klun, I., additional, Verdenik, I., additional, Pozlep, B., additional, Vrtacnik-Bokal, E., additional, Valenzano Menada, M., additional, Morotti, M., additional, Venturini, P. L., additional, Dimitriadis, E., additional, Salamonsen, L. A., additional, Hannan, N., additional, O'Connor, O., additional, Rombauts, L., additional, Stoikos, C., additional, Mahmoudi, M., additional, Shaikh, A., additional, Mousavifar, N., additional, Rastin, M., additional, Baharara, J., additional, Tabasi, N., additional, Takemura, Y., additional, Fujimoto, A., additional, Tsutsumi, R., additional, Ooi, N., additional, Yano, T., additional, Taketani, Y., additional, Panagiotidis, I., additional, Prapas, Y., additional, Zhang, D., additional, Lv, P. P., additional, Ding, G. L., additional, Zhang, R. J., additional, Zou, L. B., additional, Xu, G. F., additional, Gao, H. J., additional, Zhu, Y. M., additional, Sheng, J. Z., additional, Huang, H. F., additional, Labarta, E., additional, Alama, P., additional, and Bosch, E., additional

Published
2010
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17. Energy-dispersive X-ray fluorescence determination of platinum in plasma, urine, and cerebrospinal fluid of patients administered cis-dichlorodiammineplatinum(II).

Author

Seifert, William, Stewart, David, Benjamin, Robert, Caprioli, Richard, Seifert, W E Jr, Stewart, D J, Benjamin, R S, and Caprioli, R M

Subjects
BODY fluid analysis, CISPLATIN, PLATINUM, SPECTROPHOTOMETRY, X-ray spectroscopy
Abstract

A method involving the use of an energy-dispersive X-ray fluorescence spectrometer was developed for assaying total platinum concentrations in body fluids of patients treated with the antitumor drug cis-dichlorodiammineplatinum(II). Sample preparation by this procedure is simple, consisting in adding an internal standard (Zr) to 1 ml of biological fluid or tissue homogenate, pipetting 20 microliter of the sample onto a Mylar sample holder, and drying. This produces a thin-film sample, which effectively eliminates absorption enhancement effects due to other elements in the specimen. Standard addition studies were found to be linear in the concentration range of interest (0.1-10.0 micrograms/ml), with correlation coefficients exceeding 0.99. Minimum detection limits range from 0.10 to 0.25 micrograms Pt per ml, depending on the body fluid, which is adequate for routine patient monitoring after normal chemotherapeutic doses of cis-dichlorodiammineplatinum(II). In preliminary studies with mammalian liver, standard addition experiments were found to be linear and the minimum detection limit was found to be 1.4 micrograms/g dry weight. [ABSTRACT FROM AUTHOR]

Published
1983
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22. [C]+· and [CH]+ from doubly charged ions formed from malononitrile.

Author

Beynon, J. H., Caprioli, R. M., Cooks, R. G., Nibbering, N. M. M., and Molenaar-Langeveld, T. A.

Abstract

The metastable ions [M]2+, [M - H]2+· and [M - H2]2+ from malononitrile fragment by loss of [CH]+, [C]+· and [C]+·, respectively. The reaction of the molecular ion involves the methylene and nitrile carbon atoms in the statistical probability ratio, while that of [M - H]2+· involves exclusively the nitrile carbon and that of [M  H2]2+ involves an approximately equal contribution, from both sources. It is suggested that the metastable molecular ion fragments through a bipyrimidal intermediate. [ABSTRACT FROM AUTHOR]

Published
1975
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23. The enolic [C5H10O]+· and [C3H6O]+· ions formed from aliphatic ketones.

Author

Beynon, J. H., Caprioli, R. M., and Cooks, R. G.

Abstract

The structures of reactive and nonreactive ions formed by McLafferty rearrangement in a variety of ketones are studied using metastable ion abundances and the kinetic energy released in metastable ion fragmentations. The loss of methyl radicals is studied in [C5H10O]+. ions and the mechanism delineated for ions formed in an initial configuration corresponding both to ketonic and enolic forms; the major mechanism in both cases appears to involve a common intermediate. Partial scrambling of hydrogen atoms on the C-1 and C-5 carbons and on the oxygen precedes methyl elimination. Loss of neutral ethylene from [C5H10O]+. ions is also studied and again the major mechanism occurs via a common species, intermediate in structure between a ketone and an enol; scrambling of hydrogen is much faster for ions that lose ethylene than for those which lose a methyl radical. Keto ions of formula [C3H6O]+. show no unimolecular loss of methyl. The stable [C3H6O]+. ions generated in the keto and enol forms are shown to preserve their initial structures, confirming the results of ion cyclotron resonance experiments. Reactive [C3H6O]+. ions formed from 2-pentanone molecular ions by McLafferty rearrangement are shown to have the same structures as reactive ions originally generated as enolic structures from 1-methylcyclobutanol. The paper highlights the relationship between hydrogen scrambling and keto-enol isomerization reactions in aliphatic ketones. [ABSTRACT FROM AUTHOR]

Published
1974
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24. Genomic and Proteomic Analysis of Mammary Tumors Arising in Transgenic Mice

Author

Xie, L., Xu, B. J., Gorska, A. E., Shyr, Y., Schwartz, S. A., Cheng, N., Levy, S., Bierie, B., Caprioli, R. M., and Moses, H. L.

Abstract

Transforming growth factor-β (TGF-β) is the prototype of a large family of signaling molecules. TGF-β signaling profoundly influences tumor development as demonstrated in several engineered mouse models. The present study was designed to identify differences by cDNA microarray and MALDI-TOF MS analyses in mammary carcinomas with and without TGF-β signaling. The results demonstrate a significant potential for combination of profiling technologies to further understand the molecular mechanisms of breast cancer. Keywords: microarray • MALDI-TOF mass spectrometry • mammary tumor • transgenic mouse

Published
2005

25. Identification of Protein Fragments as Pattern Features in MALDI−MS Analyses of Serum

Author

Zimmerman, L. J., Wernke, G. R., Caprioli, R. M., and Liebler, D. C.

Abstract

The use of matrix-assisted laser desorption ionization mass spectrometry (MALDI−MS) to acquire spectral profiles has become a common approach to detect proteomic biomarkers of disease. MALDI−MS signals may represent both intact proteins as well as proteolysis products. Liquid chromatography-tandem mass spectrometry (LC−MS/MS) analysis can tentatively identify the corresponding proteins Here, we describe the application of a data analysis utility called FragMint, which combines MALDI−MS spectral data with LC−MS/MS based protein identifications to generate candidate protein fragments consistent with both types of data. This approach was used to identify protein fragments corresponding to spectral signals in MALDI−MS analyses of unfractionated human serum. The serum also was analyzed by one-dimensional SDS-PAGE and bands corresponding to the MALDI−MS signal masses were excised and subjected to in-gel digestion and LC−MS/MS analysis. Database searches mapped all of the identified peptides to abundant blood proteins larger than the observed MALDI−MS signals. FragMint identified fragments of these proteins that contained the MS/MS identified sequences and were consistent with the observed MALDI−MS signals. This approach should be generally applicable to identify protein species corresponding to MALDI−MS signals. Keywords: serum • MALDI • LC−MS/MS • bioinformatics • proteolysis

Published
2005

26. MALDI Mass Spectrometry for Direct Tissue Analysis:  A New Tool for Biomarker Discovery

Author

Reyzer, M. L. and Caprioli, R. M.

Abstract

The direct analysis of tissue sections by MALDI mass spectrometry holds tremendous potential for biomarker discovery. This technology routinely allows many hundreds of proteins to be detected over a mass range of ~2000−70 000 Da while maintaining the spatial localization of the proteins detected. This technology has been applied to a wide range of tissue samples, including human glioma tissue and human lung tumor tissue. In many cases, biostatistical analyses of the resulting protein profiles revealed patterns that correlated with disease state and/or clinical endpoints. This work serves as a review of recent applications and summarizes the current state of technology. Keywords: MALDI MS • imaging • tissues • comparative proteomics

Published
2005

27. Increased Levels of Ubiquitin in the 6-OHDA-Lesioned Striatum of Rats

Author

Pierson, J., Svenningsson, P., Caprioli, R. M., and Andren, P. E.

Abstract

Multiple genetic deficits have linked impaired ubiquitin-conjugation pathways to various forms of familiar Parkinson's disease. We therefore examined the possible role of 6-hydroxydopamine, a dopaminergic neurotoxin used in Parkinson's disease experimental models, in causing protein degradation and its association with the ubiquitin proteasome system. Using unilaterally 6-hydroxydopamine-denervated rats and mass spectrometry profiling directly on brain tissue sections, we here report for the first time an increased level of unconjugated ubiquitin specifically in the dorsal striatum of the dopamine depleted hemisphere. No similar changes were found in the intact hemisphere or in the ventral striatum of the dopamine depleted hemisphere. The lesioning of the dopamine innervation to the striatum was confirmed by a strongly reduced dopamine transporter binding in the striatum, indicating an abundant loss of dopamine neurons. These results suggest that denervation of dopamine neurons per se is implicated in the regulation of ubiquitin pathways, at least in a classical animal model of Parkinson's disease. This study adds additional information regarding the involvement of the ubiquitin−proteasome system in Parkinson's disease. Keywords: Parkinson's disease • profiling mass spectrometry • proteomics • neurotoxin • proteasome • 6-OHDA • rat • MALDI • brain

Published
2005

28. Molecular Profiling of Experimental Parkinson's Disease:  Direct Analysis of Peptides and Proteins on Brain Tissue Sections by MALDI Mass Spectrometry

Author

Pierson, J., Norris, J. L., Aerni, H.-R., Svenningsson, P., Caprioli, R. M., and Andren, P. E.

Abstract

Direct molecular profiling of biological samples using matrix-assisted laser desorption ionization mass spectrometry is a powerful tool for identifying phenotypic markers. In this report, protein profiling was used for the first time to generate peptide and protein profiles of brain tissue sections obtained from experimental Parkinson's disease (unilaterally 6-hydroxydopamine treated rats). The mass spectrometer was used to map the peptide and protein expression directly on 12 μm tissue sections in mass-to-charge (m/z) values, providing the capability of mapping specific molecules of the original sample, that is, localization, intensity and m/z ratio. Several protein expression profile differences were found in the dopamine depleted side of the brain when compared to the corresponding intact side, for example, calmodulin, cytochrome c, and cytochrome c oxidase. An increased ratio of post-translational modifications such as acetylations were found in the striatum of proteins in the dopamine depleted side of the brain. These modifications were decreased after subchronic administration of l-Dopa. The present study shows that unique protein profiles can be obtained in specific brain regions (and subregions) directly on brain tissue sections and allows for the study of complex biochemical processes such as those occurring in experimental Parkinson's disease. Keywords: Parkinson's disease • striatum • cortex • post-translational modifications • l-Dopa • MALDI

Published
2004

29. Assessing Protein Patterns in Disease Using Imaging Mass Spectrometry

Author

Chaurand, P., Schwartz, S. A., and Caprioli, R. M.

Abstract

Direct tissue profiling and imaging mass spectrometry (MS) provides a detailed assessment of the complex protein pattern within a tissue sample. MALDI MS analysis of thin tissue sections results in over of 500 individual protein signals in the mass range of 2 to 70 kDa that directly correlate with protein composition within a specific region of the tissue sample. To date, profiling and imaging MS has been applied to multiple diseased tissues, including human gliomas and nonsmall cell lung cancer. Interrogation of the resulting complex MS data sets has resulted in identification of both disease-state and patient-prognosis specific protein patterns. These results suggest the future usefulness of proteomic information in assessing disease progression, prognosis, and drug efficacy. Keywords: mass spectrometry • MALDI • profiling • imaging • cancer

Published
2004

30. Rearrangement of the benzyl benzoate molecular ion to lose H2O.

Author

Beynon, J. H., Caprioli, R. M., Shapiro, R. H., Tomer, K. B., and Chang, C. W. J.

Abstract

The molecular ion of benzyl benzoate undergoes several decompositions, two of which are the loss of H 2O and COOH·. To study these processes, the mass and IKE spectra of benzyl benzoate together with various deuterated benzyl benzoates and some of its isomers were studied. Evidence is presented to support the rearrangement processes of the molecular ion. A decomposition scheme is proposed to explain the observed transitions. [ABSTRACT FROM AUTHOR]

Published
1972
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31. Charge localization: The ion kinetic energy spectra of pyrazine, pyrimidine and pyridazine.

Author

Beynon, J. H., Caprioli, R. M., and Ast, T.

Abstract

The ion kinetic energy (IKE) spectra of pyrazine, pyrimidine, pyridazine, pyrazine- d4, pyrimidine- d4 and pyridazine- d4 have shown that these compounds can more readily be distinguished on the basis of IKE spectra than mass spectra. Studies of the fragmentation of various doublycharged ions have given information about the localization of charge on the heteroatoms and on the structures of the ions themselves. Transition states from which fragmentation occurs for doublycharged ions with loss of either [H]+ or [D]+ have shown large differences of the order 1 Å between the intercharge distances in the two cases. [ABSTRACT FROM AUTHOR]

Published
1972
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32. The structure of the product ion of a 'McLafferty' rearrangement.

Author

Beynon, J. G., Caprioli, R. M., and Shannon, T. W.

Abstract

A series of alkylphenylketones has been examined. Whenever the alkyl chain is three or more carbon atoms long, the well-known McLafferty rearrangement occurs with elimination of the elements of a neutral olefin. The further fragmentation of the ion formed in this rearrangement reaction has been studied using the technique of ion kinetic energy (IKE) spectroscopy. The measured release of kinetic energy has been used to show that the rearrangement ion has an enolic type structure. [ABSTRACT FROM AUTHOR]

Published
1971
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33. The fragmentation of aliphatic ketones in the mass spectrometer: A detailed study of nonan-4-one using ion kinetic energy spectroscopy.

Author

Eadon, George, Djerassi, Carl, Beynon, J. H., and Caprioli, R. M.

Abstract

The ion kinetic energy (IKE) spectra of nonan-4-one, 7,7-d2-nonan-4-one and 1,1,1-d3-nonan-4-one have been recorded and interpreted. The various fragmentations observed in the IKE spectra have been confirmed and some new fragmentations found by carrying out high voltage scans with the magnetic field set successively to collect ions at each mass to charge ratio throughout the mass spectrum. Several new fragmentation modes have been discovered, and their significance is discussed. [ABSTRACT FROM AUTHOR]

Published
1971
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34. Charge localization-I The ion kinetic energy spectra of ortho-, meta- and para-phenylenediamine.

Author

Caprioli, R. M., Beynon, J. H., and Ast, T.

Abstract

The ion kinetic energy spectra of o-, m-and p-phenylendiamine are presented. Decompositions of doubly-charged ions are given for the three isomers. From the width of the peaks, the energy released is measured and the equivalent intercharge distance is calculated. The results are discussed in terms of possible structures of the various ions. Also, metastable transitions which could give rise to peaks corresponding to energies below that of the mainion beam are listed and the results discussed. Significant differences were observed among the energy spectra of the three isomers. [ABSTRACT FROM AUTHOR]

Published
1971
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35. The effect of deuterium labeling on the width of a 'metastable peak'.

Author

Beynon, J. H., Caprioli, R. M., and Ast, T.

Abstract

Studies have been made of the energy release during the decomposition of metastable ions in the mass spectra of pyrazine, pyrazine-d4, pyrimidine, pyrimidine-d4, pyridazine and symmtriazine. In all the compounds except pyridazine very small amounts of energy have been measured in some processes. The recorded energy release of 187 μeV for a transition of the symmtriazine molecular ion is the smallest energy release yet recorded. In the case of pyrazine and pyrimidine the energy release in one transition was found to be smaller than in the corresponding transition in the -d4 analogues. [ABSTRACT FROM AUTHOR]

Published
1971
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36. The expulsion of OH˙ from the [M  C2H4]+˙ ion from ethyl benzoate: Ring-deuterated compounds.

Author

Shapiro, R. H., Tomer, K., Beynon, J. H., and Caprioli, R. M.

Abstract

Mass spectra and ion kinetic energy (IKE) spectra of o-, m- and p-d1 ethyl benzoates have given further information on the loss of OH˙ and OD˙ from the [M  C2H4]+˙ ions. The 'metastable peaks' in the mass spectra give information on fragmentations in the field-free region following the electric sector; the IKE spectra give information on fragmentations in the field-free region preceding this sector. Transfer of hydrogen and deuterium from the ortho-positions on the ring to the carboxyl group can occur, but scrambling of ring hydrogens does not take place. A sample of o-d1 benzoic acid was also examined and confirmed that similar transfer reactions occur in this compound too. [ABSTRACT FROM AUTHOR]

Published
1970
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37. The 'preference factor' and isotope effect in the loss of hydrogen or deuterium from labeled toluenes.

Author

Beynon, J. H., Corn, J. E., Baitinger, W. E., Caprioli, R. M., and Benkeser, R. A.

Abstract

Metastable ion decompositions involving the loss of hydrogen and deuterium from partially deuterated toluene ions were studied using a double focusing mass spectrometer. The electric sector voltage was adjusted so that the only ions transmitted were those which lost a particular fraction of their kinetic energy in decompositions taking place in front of the electric sector. Transitions involving loss of mass 1 or mass 2 from the molecular ions of toluene-α- d3 and toluene-2,3,4,5,6- d5 were studied. The results showed that in these slow reactions, the 'preference factor' defined as the ratio of the probability of loss of a hydrogen atom from a side-chain position to loss of a hydrogen atom from a ring position was 1.00. The 'isotope factor,' defined as the ratio of the probability of loss of a hydrogen atom from any position to that for the loss of a deuterium atom from the same position was found to be 3·50. [ABSTRACT FROM AUTHOR]

Published
1970
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39. The decomposition of a triply-charged metastable positive ion of biphenyl.

Author

Beynon, J. H., Caprioli, R. M., Baitinger, W. E., and Amy, J. W.

Abstract

The transition, [C12H10]+3→[C11H7]+2 + [CH3]+, has been detected both in the ion kinetic energy spectrum and in the mass spectrum of biphenyl. The width of a resulting 'metastable peak' has been measured by setting the magnetic field to accept [C11H7]+2 ions and scanning the high voltage at fixed electric sector voltage. The kinetic energy released in the decomposition, calculated from the peak width, amounted to 4.5 eV. With the assumption that this energy release is due entirely to charge separation, the charge distribution in [C12H10]+3 is discussed. The derivation of the equations used to calculate the energy released is given in the Appendix. [ABSTRACT FROM AUTHOR]

Published
1970
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40. Metastable ions of methane and their use in calibrating a low mass scale.

Author

Beynon, J. H., Caprioli, R. M., Baitinger, W. E., and Amy, J. W.

Abstract

The decomposition of metastable positive ions of methane formed by electron bombardment is discussed. Some new collision-induced decompositions involving the formation of H+, H2+˙ and H3+ have been found in the ion kinetic energy spectrum as well as in the mass spectrum of methane. In the latter case, the 'metastable peaks' occur below mass 1 on the mass scale and can be used for mass calibration in this region of the mass spectrum. [ABSTRACT FROM AUTHOR]

Published
1970
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41. The ion kinetic energy spectra of some aromatic hydrocarbons.

Author

Beynon, J. H., Caprioli, R. M., Baitinger, W. E., and Amy, J. W.

Abstract

The technique of ion kinetic energy spectroscopy has been applied to the study of the aromatic hydrocarbons benzene, toluene, naphthalene, 2-methyl naphthalene, biphenyl and anthracene. The method is illustrated by a complete study of naphthalene in which transitions of metastable doubly- and singly-charged ions are listed, including reactions in which singly-charged ions are formed by collision induced charge-exchange reactions of doubly-charged ions and by the double process of charge-exchange and metastable decomposition with loss of one or two hydrogen atoms. Decompositions of doubly-charged ions into two singly-charged ions, together with the kinetic energies released in these decompositions, are also given for all the compounds studied. [ABSTRACT FROM AUTHOR]

Published
1970
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