Abstract
Infrared spectrophotometric methods for the determination of isolated trans isomers in fats and oils were studied collaboratively, using methyl elaidate, methyl stearate, and methyl esters of partially hydrogenated vegetable oils. A study was made to compare the AOCS tentative method with the IUPAC standard method. As the results of the collaborative tests, the IUPAC method was found to be more accurate than the AOCS tentative method. More accureate results, however, could be attainable by using a modified base line from 1050cm-1 to 940cm-1 in the AOCS tentative method. Furthermore, the influence of the methods of preparing methyl esters on the determination of isolated trans isomers was studied. Both the BF3-and H2SO4-methanol methods were consequently suitable for the preparation of methyl esters on the determinatiton of isolated trans isomers in fats and oils.
