Determination of iodine value of palm and palmkernel oil by carbon-13 nuclear magnetic resonance spectroscopy

High resolution carbon-13 nuclear magnetic resonance (C-13 NMR) can be used for characterization of palm oil and palmkernel oil in determining the iod ine value (IV) of the oil. It is only necessary to obtain the quantitative C-13 NMR spectrum of the oil in dilute CDCl3 solution in the region of delt a 30.0-delta 24.7 ppm, which pertains to the methylene carbons along the ac yl chain from the beta -carbonyl to the omega -4. From the peak areas in th e spectrum the average number of double bonds per triacylglycerol molecule and the average molecular weight can be calculated and hence the IV. The IV s of 18 samples of palm and palmkernel oil have been determined by C-13 NMR and by the Official Method of the American Oil Chemists' Society. There is good agreement between the two sets of IVs. Conditions for obtaining relia ble IVs by this C-13 NMR method are given.