Análise do teor e da qualidade dos lipídeos presentes em sementes de oleaginosas por RMN de baixo campo
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Data
2013-02-27
Autores
Constantino, André Fazolo
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Universidade Federal do Espírito Santo
Resumo
In order to choose from the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different experiments of low-field 1H Nuclear Magnetic Ressonance (NMR) with varied pulse sequences, namely single pulse, spin-echo, CPMG and CWFP (Continuous Wave Free Precession). The experiments applying the first three sequences showed high correlation with each other and with the solvent extraction method. The best results were achieved through CPMG experiments. When the CWFP sequence was used, the correlation with the solvent extraction method was very low and the results were not compatible with those employing the other sequences. Quality of the vegetable oils was also evaluated. The study was based on the existing correlation between the T2 values of the oils obtained through 1H NMR signals achieved through CPMG and their properties, such as viscosity, iodine index and cetane index. These analyses were carried out using HCA and PCA chemometric tools. The results were significant enough to separate the oleaginous matrices according to their quality. The signals achieved using the CWFP and CP-CWFP (Carr-Purcell - Continuous Wave Free Precession) sequences were also used in the chemometric analyses. However, the study identified that the signals generated from these sequences depend both on T1 and T2. Therefore except for the most viscous oleaginous matrices, in HCA and PCA analyses, the matrices were not grouped according to their qualities. The experiments carried out through CP-CWFP were even more advantageous than those through CWFP because the former had higher signal amplitude variation in the quasi steady state (QSS). Thus, using the most adequate pulse sequence, the low-field 1H NMR technique was confirmed as an important tool to help selecting oleaginous matrices for biodiesel production.
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Palavras-chave
Low-field NMR , Biodiesel , Oil content , Oil quality , Oilseeds , Biofuel , Nuclear Magnetic magnetic resonance spectroscopy , Magnetic resonance imaging , Sementes oleaginosas , Biodiesel , Espectroscopia de ressonância magnética nuclear , Ressonância magnética , RMN de baixo campo , Biodiesel , Teor de óleo , Qualidade do óleo
Citação
CONSTANTINO, André Fazolo. Análise do teor e da qualidade dos lipídeos presentes em sementes de oleaginosas por RMN de baixo campo. 2013. 111 f. Dissertação (Mestrado em Mestrado em Química) – Universidade Federal do Espírito Santo, Vitória, 2013.