Direct FTIR analysis of isolated trans fatty acids in edible oils using disposable polyethylene film

A new transmission-based Fourier transform infrared (FTIR) spectroscopy method has been developed to determine trans fatty acids (TFA) content in edible oils using disposable polyethylene (PE) film as a spectral acquisition accessory. Calibration standards were devised by gravimetrically adding TFA to TFA-free oil. The response was measured at 990-945 cm−1 against the baseline. A linear relationship between the areas in the spectral regions 1670-1625 cm−1 and 990-945 cm−1 in TFA-free oil samples was established to compensate for interference due to underlying triacylglycerol absorptions in the trans measurement region (990-945 cm−1). Subsequently, the area measured at 990-945 cm−1 was corrected for interference, using the linear equation obtained, to determine TFA content. Results indicated that the PE film-based FTIR method for analyzing TFA content in edible oils was simple and rapid, and could be used effectively as an alternative to gas chromatography and mass spectrometry methods.