title: Differently saturated fatty acids can be differentiated by 31P NMR subsequent to derivatization with 2-chloro-4,4,5,5-tetramethyldioxaphospholane: a cautionary note.
abstract: The analysis of free fatty acid (FFA) mixtures is a very important but, even nowadays, challenging task. This particularly applies as the so far most commonly used technique-gas chromatography/mass spectrometry (GC/MS)-is tedious and time-consuming. It has been convincingly shown ( Spyros, A.; Dais, P. J. Agric. Food Chem. 2000, 48, 802 - 5) that FFA may be analyzed by (31)P NMR subsequent to derivatization with 2-chloro-4,4,5,5-tetramethyldioxaphospholane (CTDP). However, it was also indicated that differently unsaturated FFAs result in the same (31)P NMR chemical shift and cannot be differentiated. Therefore, only the overall fatty acid content of a sample can be determined by the CTDP assay. In contrast, we will show here by using high-field NMR (600 MHz spectrometer, i.e., 242.884 MHz for (31)P) that the CTDP assay may be used to differentiate FFAs that have pronounced differences in their double bond contents: saturated fatty acids (16:0), moderately unsaturated (18:1, 18:2), highly unsaturated (20:4), and extremely unsaturated fatty acids (22:6) result in slightly different chemical shifts. The same applies for oxidized fatty acids. Finally, it will also be shown that the CTDP derivatization products decompose in a time-dependent manner. Therefore, all investigations must adhere to a strict time regime.
authors: Medical Faculty, Institute of Medical Physics and Biophysics, University of Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany.
authors: Mandy
authors: M
authors: Eibisch
authors: Thomas
authors: T
authors: Riemer
authors: Beate
authors: B
authors: Fuchs
authors: Jürgen
authors: J
authors: Schiller
mesh_terms: D005227:Fatty Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009943:Organophosphorus Compounds / Q000737:chemistry
chemical_list: C548759:2-chloro-4,4,5,5-tetramethyldioxaphospholane; D005227:Fatty Acids; D009943:Organophosphorus Compounds