Diffusion Coefficient-Formula Weight Correlation Analysis via Diffusion-Ordered Nuclear Magnetic Resonance Spectroscopy (DOSY NMR) To Examine Acylglycerol Mixtures and Biodiesel Production
نویسندگان
چکیده
Biodiesel, fatty acid methyl esters derived from vegetable oils, is a well-established alternative to petroleum diesel. We have developed a rapid H diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY NMR)method to resolve mixtures of mono-, di-, and triacyglycerols alongwith their methyl esters. Because of the differences in diffusion coefficients between the starting materials (triglycerides), intermediates (monoand diglycerols), and products (methyl esters), we were able to accurately predict the formula weights of these species in solution. This techniquewas used tomonitor transesterification reactions of virgin andwaste vegetable oils. In addition to proving its utility to assess conversion of startingmaterials, we found that 1,3-diacylglycerol is the major intermediate formed during alkali-catalyzed biodiesel production.
منابع مشابه
Directly Decoupled Diffusion-Ordered NMR Spectroscopy for the Analysis of Compound Mixtures
For the analysis of compound mixtures by NMR spectroscopy, it is important to assign the different peaks to the individual constituents. Diffusion-ordered spectroscopy (DOSY) is often used for the separation of signals based on their self-diffusion coefficient. However, this method often fails in the case of signal overlap, which is a particular problem for (1)H-detected DOSY spectra. Herein, a...
متن کاملDiffusion-Ordered (DOSY) NMR of Solute Exchange Across the Human Erythrocyte Membrane: including an application of Post- Widder Laplace inversion
Nuclear magnetic resonance (NMR) spectroscopy was used to study exchange of three distinctly different molecules across the membranes of human red blood cells (RBCs). In studying water, t-butanol, and dimethyl sulfoxide we exploited the marked differences in the apparent diffusion coefficients of these species inside and outside the cells in suspensions. The measurements were made with diffusio...
متن کاملAssessment of techniques for DOSY NMR data processing
Diffusion-ordered spectroscopy (DOSY) NMR is based on a pulse-field gradient spin-echo NMR experiment, in which components experience diffusion. Consequently, the signal of each component decays with different diffusion rates as the gradient strength increases, constructing a bilinear NMR data set of a mixture. By calculating the diffusion coefficient for each component, it is possible to obtai...
متن کاملDiffusion ordered spectroscopy as a complement to size exclusion chromatography in oligosaccharide analysis.
A series of N-acetyl-chitooligosaccharides (GlcNAc)(1-6) have been studied by a nuclear magnetic resonance (NMR) method, diffusion ordered spectroscopy (DOSY). DOSY has also been applied to two additional synthetic related oligosaccharides [GlcNH(2)-(GlcNAc)(4) and GlcNH(2)-(GlcNAc)(2)-GlcNAcSO(3)Na]. A plot of the log of the determined diffusion coefficients (logD) of (GlcNAc)(n) versus the lo...
متن کاملThe 2D-J-DOSY experiment: resolving diffusion coefficients in mixtures.
Many diffusion-ordered spectroscopy (DOSY) NMR techniques have recently been developed to aid in the deconvolution of complex mixtures. Spectroscopic separation based on chemical and physical properties facilitates the identification of mixture components while eliminating time-consuming separation steps and preserving the chemical environment. One way to improve resolution in such experiments ...
متن کامل