Vibrational structure of the polyunsaturated fatty acids eicosapentaenoic acid and arachidonic acid studied by infrared spectroscopy

The spectroscopic discrimination of the two structurally similar polyunsaturated C-20 fatty acids (PUFAs) 5,8,11,14,17-eicosapentaenoic acid and 5,8,11,14-eicosatetraenoic acid (arachidonic acid) is shown. For this purpose their vibrational structures are studied by means of attenuated total reflection (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The fingerprint regions of the recorded spectra are found to be almost identical, while the C-H stretching mode regions around 3000 cm(-1) show such significant differences as results of electronic and molecular structure alterations based on the different degree of Saturation that both fatty acids can be clearly distinguished from each other. (C) 2009 Elsevier B.V. All rights reserved.