¹H NMR and Multivariate Calibration for the Prediction of Biodiesel Concentration in Diesel Blends

Abstract

In this work, the use of 1 H-NMR spectroscopy and a statistical approach to the analysis of biodiesel concentrations in blends with conventional diesel is described. For this, we performed 1 H-NMR analyses using distinct mixtures of biodiesel from soybean and castor oil in mineral diesel, in concentrations ranging from 0.5 to 30%, and then we applied partial least squares regression (PLS) and principal components regression (PCR) to such data. So, six models were designed and they were evaluated through statistical parameters and through the analysis of four samples prepared in the laboratory. Briefly, a PLS model, obtained through the selection of aromatic, aliphatic and methoxy spectral regions, was quite suitable for the prediction of biodiesel concentrations greater than 2.0%. Deviations of real and predicted values were found to B2 commercial blends, indicating that this model can only be applied to blends exceeding a 2.0% level of biodiesel in petroleum diesel. In conclusion, the 1 H-NMR-PLS method is fairly useful for the quality control of biodiesel-diesel blends, whose commercialisation has increased in the last few years.

Molecular Properties of Fatty Acid Mixtures Estimated by Online Time-Domain NMR

“…High-resolution nuclear magnetic resonance (NMR) spectroscopy is a standard technique for molecular structure and molecular mobility investigations of different substances and is well established in the chemical analysis of liquid fuels [3,[6][7][8][9][10]. However, traditional high-resolution NMR spectrometers are hardly applied to industrial process control due to their open magnetic field, large size and high price and the required cryogen use.…”

Análise De Amostras De Combustíveis Por Fotometria, Nir Portátil E RMN De 1 H – Uma Comparação Com Os Resultados Encontrados Por Técnicas Normatizadas

“…15 Na análise de combustíveis, as principais regiões de interesse são as referentes aos grupos de hidrogênios alifáticos, aromáticos e olefínicos, cujos deslocamentos químicos são consolidados na literatura. 10,[16][17][18][19] Outra técnica bastante empregada no estudo de combustíveis devido principalmente ao seu baixo custo e simplicidade é a espectroscopia na região do infravermelho próximo (NIR). A capacidade do NIR em obter informações sobre ligações químicas distintas permite estudar os compostos constituintes da gasolina, etanol e óleo diesel a partir de grupos funcionais moleculares do tipo C-H, S-H, N-H e O-H que absorvem frequências na faixa de 4.000-14.000 cm -1 .…”

“…Estes resultados são considerados satisfatórios quando comparados aos obtidos pelos métodos especificados na ANP 309. 8,9 Monteiro et al 10 utilizaram a espectroscopia de ressonância magnética nuclear de próton (RMN de 1 H) associada à métodos quimiométricos (regressão por mínimos quadrados parciais (PLS)…”

Medium Resolution NMR at 20 MHz: Possibilities and Challenges

“…Detailed studies of compositions, for example in food and oil industries [1][2][3][4] , are of great importance to guarantee a high and constant quality and well defined properties of a product. Many applications still need expensive analytical techniques like high resolution NMR (Nuclear Magnetic Resonance) to determine each component"s concentration like the marginal amounts of acids, colorants or polyphenols 5 in wine analysis 6 or small amounts of special fatty acids in virgin olive oils 7 .…”