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| Author(s): |
Mario Benassi Neto
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2010-06-16 |
| Examining board members: |
Marcos Nogueira Eberlin;
Luiz Alberto Beraldo de Moraes;
Gilberto Alves Romeiro;
Fábio Cesar Gozzo;
Paulo José Samenho Moran
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| Advisor: | Marcos Nogueira Eberlin |
| Abstract | |
Herein, it¿s described an absolute method for structure assignment of constitutional isomers exploring the gas phase behavior of a structurally diagnostic fragment ion (SDFI) generated by each one of the precursor molecules within an isomeric set. This method allows the unequivocally assigning of the configuration of a precursor isomer with only one mass spectrum. To prove the principle the following isomeric sets were tested: acetonaphthone, alkylanilines, carbetoxypiperidines, methylthiophenes, cyclohexene carboxylic acids and methylpiperidines. All of the precursor isomers were submitted to 70 eV electron ionization (EI) with the intent of identifying the proper SDFI for each of the isomeric sets. Ideally, the SDFI should have the following characteristics: i) must be formed by all the isomers within the isomeric set, ii) retain the structural information of the precursor molecule, iii) be stable (long lifetime) and iv) the SDFI generated from different precursors must have different structures and must not interconvert into one another. The m/z of the SDFI is selected and then submitted to collision induced dissociation, hoping that the dissociative behavior is different depending on the precursor molecule, and ion/molecule reactions, hoping the bimolecular chemistry is different due to the formation of different ion products. For all the experiments it was used a pentaquadrupole mass spectrometer that allows MS/MS/MS, therefore allowing characterization of the ion products generated by ion/molecule reactions through collision induced dissociation. (AU) | |