title: Quantitation of isomeric ethyl pyridine mixtures by multivariate calibration applied to ion-molecule reaction/collision-induced dissociation triple-stage mass spectra.
abstract: In reactions of the distonic ion (+)CH(2)OCH(2) with the three isomeric ethyl pyridines, ionized methylene transfer occurs readily yielding distonic N-methylene-ethylpyridinium ions. On-line mass selection and 10 eV collision-induced dissociation (CID) of the CH(2)(+) transfer products yields characteristic fragment ions, which are formed via processes greatly influenced by the ortho, meta or para location of the ethyl substituent in the pyridine ring. Quantitation of mixtures of isomeric 2-, 3-, and 4-ethyl pyridines of varying compositions was then performed by multivariate calibration in the form of the partial least square (PLS) model applied to both single-stage (MS) 70 eV electron ionization (EI) and pentaquadrupole triple-stage sequential ion-molecule reaction/CID product ion mass spectra. The results exemplify the superior ability of combined chemometric analysis and sequential mass spectrometric techniques, which benefits from both characteristic ion chemical reactivity and dissociation behavior, for rapid and accurate quantitation of complex isomeric mixtures.
authors.affiliation: Instituto de Quimica, Universidade Estadual de Campinas, UNICAMP, Caixa Postal 6154, CEP 13083-970 Campinas, São Paulo, Brazil.
authors.forename: Cleidiane G
authors.initials: CG
authors.lastname: Zampronio
authors.forename: Luis Alberto B
authors.initials: LA
authors.lastname: Moraes
authors.forename: Marcos N
authors.initials: MN
authors.lastname: Eberlin
authors.forename: Ronei J
authors.initials: RJ
authors.lastname: Poppi