Supercritical Fluid Chromatography of Free Fatty Acids with On-Line FTIR Detection

Abstract

The separation and detection of free fatty acids (FFAs) by supercritical fluid chromatography/Fourier transform infrared detection (SFC/FTIR) is demonstrated with an analytical-scale packed column method. FFAs in simple mixtures are separated by carbon number with supercritical CO₂ and Freon 23 on Hamilton PRP-1 packings. Components are detected easily by strong absorbances at approximately 1700, 3000, and 3550 cm^-1 infrared (IR) regions. FFAs extracted from butter, soap, soybean oil, and coconut oil samples could be easily identified. Retention time correlation to standard mixtures is necessary to differentiate between the different carbon number acids. The infrared spectra within each chromatographic peak provide information as to the extent of dimerization and the degree of unsaturation in the eluted component.