LIQUID-CHROMATOGRAPHIC MASS-SPECTROMETRIC ANALYSIS OF CONJUGATED DIENE FATTY-ACIDS IN A PARTIALLY HYDROGENATED FAT

A commercially available partially hydrogenated fat was analyzed for f atty acids containing conjugated dienes. The fatty acids were isolated by high-performance liquid chromatography (HPLC), and analyzed with a photodiode array detector and an atmospheric-pressure ionization mass spectrometer. Conventional and second-derivative ultra-violet (UV) sp ectra of the peaks eluting from the HPLC were recorded with the photod iode array detector, and peaks displaying second-derivative UV spectra characteristic of the conjugated diene chromophore were analyzed by m ass spectrometry. The UV and mass spectra of the fatty acids with conj ugated dienes, present in the partially hydrogenated fat, were identic al to those of reference preparations of linoleic acid isomers with co njugated dienes. The results obtained emphasize that care must be exer cised in the interpretation of clinical and experimental data concerni ng the detection of conjugated dienes in tissues or body fluids of hum ans and experimental animals. The conjugated dienes may not reflect an ongoing process of lipid peroxidation, but may be of dietary origin.