Uso da pirólise acoplada à cromatografia gasosa e à espectrometria de massas na determinação da relação siringil/guaiacil em ligninas de clones de Eucalyptus spp

• Autor(a) principal: Nunes, Cleiton Antônio
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2046
• topic: Eucalyptus; Lignina; Pirólise analítica; Eucalyptus; Lignins; Analytical pyrolysis; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA

The syringyl/guaiacyl ratio (S/G) was determined in wood of six different Eucalyptus clones cultivated in four regions of Minas Gerais Brazilian state. The determinations were accomplished by pyrolysis coupled with gaseous chromatography and mass spectrometry (Py-GC/MS) and the obtained results were compared to reference values obtained by alkaline nitrobenzene oxidation method. The S/G ratio calculations were accomplished considering all the lignin compounds derived identified in the pyrograms and through two markers groups. The first group considered the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, trans-isoeugenol, syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-propenylsyringol as markers. The second group considered as markers, the compounds guaiacol, 4- methylguaiacol, 4-vinhylguaiacol, vanilin, 4-ethylsyringol, 4- vinylsyringol, homovanilin, syringaldehyde, syringylcetone and trans-4-propenylsyringol. Through the t test, it was verified that the values obtained through the markers compounds didn't differ significantly from the reference values, unlike the determinations witch all were considered the lignin compounds derived. The second markers group was shown to be more suitable for presenting more defined picks in the pyrograms. The Principal Component Analysis showed that the compounds trans-4-propenylsyringol, the 4-vinylsyringol and the syringol were responsible for promoting distinctions among the samples and that the S/G ratio values came with little variation among the several clones cultivated in the different regions.