Simple Methods via Mid-IR or¹H NMR Spectroscopy for the Determination of the Iodine Value of Vegetable Oils

Abstract

Two methods for determining the iodine value in vegetable oils are described. One employs mid-infrared (mid-IR) spectroscopy and the other uses hydrogen nuclear magnetic resonance ( 1 H NMR). The determination of the iodine value is based on either the transmittance intensity of mid-IR signals or on the 1H NMR signal integration and multivariate calibration. Both of the methods showed adequate coefficients of determination (r 2 = 0.9974 and 0.9978, respectively) when compared to Wijs method, which is recommended by the norm EN 14111. A statistical comparison between the results from the proposed methods and from Wijs method shows that both instrumental methods offer equivalent results and greater precisions compared to Wijs method. The regressions obtained from the constructed models were considered statistically significant and useful for making predictions. The proposed methods present several advantages compared to Wijs method because they significantly reduce analysis time, reagent consumption and waste generation. Furthermore, an analyst can choose between the mid-IR or 1 H NMR to determine the iodine value. ]]>

Experimental Investigation of Stability of Vegetable Oils Used as Dielectric Fluids for Electrical Discharge Machining

“…After machining, the oils' spectra showed the same tendency of variation as that of the sunflower oil, as shown in Figure 2b- The FTIR spectra registered for the sunflower oil revealed that there were no appreciable differences in the spectral features before and after processing, as well as between different working regimes, apart from changes in the intensity of some absorption bands; the most relevant change was within the range of 1465-721 cm −1 , where an increase in the absorbance of the oil corresponding to the middle intensive working regime (E1181) and a slight decrease of the absorbance of the oil corresponding to the most intensive working regime (E1191), were recorded. The obtained spectra are in very good agreement with those presented in the literature [32].…”

Salvia hispanica L. (Chia) Oil as a Potential Renewable Raw Material for the Production of Air-Dry Alkyd Resins

“…In the spectrum of chia oil in Figure A, the assigned numbers 3, 4, 6, 7, 9, and 10 correspond to the olefinic signals from the hydrogens on the fatty acid tails . These signals are evident in both the linolenic and linoleic fatty acid tails.…”

Incorporation of astrocaryum vulgare (tucuma) oil into PCL electrospun fibers

“…The FTIR-ATR spectrum of tucuma oil, PCL and PCL + tucuma oil are shown in Figure 2 and it contains characteristics bands of a vegetable oil [42][43][44][45] . These bands are described in Table 2, according to the findings of Leonardi et al [42] , Ali et al [44] and Gomez et al [45] .…”