Estimation of Glycerides and Free Fatty Acid in Oils Extracted From Various Seeds from the Indian Region by NMR Spectroscopy

Abstract

The present study is focused on the quantification of glycerides and free fatty acid in oils extracted from various seeds for biodiesel production from Indian territory. A new method based on 1 H-and 13 C-NMR spectroscopic techniques was developed in order to estimate triglycerides (TG), diglycerides, monoglycerides, free fatty acids (FFA) and various other components such as para-substituted phenols, silylated methyl esters, aromatic acids, naphthalenes, etc. Iodine values of the extracted oils were estimated using the developed 1 H-NMR spectroscopic method, which was correlated with the TG content present in the sample. Results by the NMR method were validated by the blend preparation, fatty acid composition determined by the GC and from the iodine value of the samples. The developed method is direct, rapid and no sample treatment is required. The results from these comprehensive studies indicated that NMR spectroscopic technique is useful for the quantification of extracted oils and can be used effectively for the development and monitoring of biodiesel production and determining the fuel quality.

NMR Determination of Free Fatty Acids in Vegetable Oils

“…Despite the potential spectral overlap, the 1 H NMR method found several applications. It was exploited, for instance, to estimate the FFA content in non-edible oils extracted from thirteen seeds from India [47], to follow the change in the amount of FFA and other components in different developmental stages of a non-edible oilseed, Jatropha curcas L. [48], or to detect and quantify all the different constituents, including FFA, coming from the hydrolysis of triglycerides during lipolysis [49]. More recently 1 H NMR was also applied to assess the quality especially in terms of the FFA content of biodiesel produced by transesterification of oil from J. curcas L. seeds [50].…”

“…The strong discriminating power of the 13 C NMR method in the carbonyl region was demonstrated, for instance, in the estimation of the amount of FFA in non-edible oils extracted from various seeds from India [47], or in oil extracted from commercial samples of grated mullet roe (bottarga) [55].…”

A method based on 1H NMR spectral data useful to evaluate the hydrolysis level in complex lipid mixtures

“…It has to be noted that in other 1 H NMR studies on biodiesel, edible oils and fats with a low degree of hydrolysis, the area of the signal centered at near 2.344 ppm is used to determine exclusively the content of FA (Kumar et al, 2011;Satyarthi, Srinivas, & Ratnasamy, 2009). However, due to the overlapping in this spectral region among signals of TG, DG, MG and FA, this quantification of FA would lead to an overestimation if the formers are also present in the sample.…”

comparison of oil extraction methods for algae by NMR and Chromatographic techniques

“…Detailed chemical composition of algae biomass is essential to understand the chemistry of neutral and polar lipids to explore their biodiesel and high value product potential as well as help in the prediction of quality, yield and physio-chemical properties of the algae derived fuels. Therefore, analytical methods based on NMR [7,8,14,24,[29][30][31][32][33][34][35][36][37][38][39] , GC/GC-MS [7,8,40,41] , IR [24,42] and HPLC [43] techniques are used to characterize and determine the neutral lipids content and their fatty acids composition of the algal oils. The importance of solvent polarity in the extraction of lipids and their composition, fatty acid profile, and yield has been reported from critical analyses of extracted oils obtained by different solvents by GC-MS and gravimetric methods [21] .…”