Analytical Sciences

Abstract − Analytical Sciences, 21(12), 1457 (2005).

Rapid Discrimination of Fatty Acid Composition in Fats and Oils by Electrospray Ionization Mass Spectrometry
Shoji KURATA,* Kazutaka YAMAGUCHI,* and Masatoshi NAGAI**
*Criminal Investigation Laboratory, Metropolitan Police Department, 2-1-1, Kasumigaseki, Chiyoda-ku, Tokyo 100-8929, Japan
**Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei, Tokyo 184-8588, Japan
Fatty acids in 42 types of saponified vegetable and animal oils were analyzed by electrospray ionization mass spectrometry (ESI-MS) for the development of their rapid discrimination. The compositions were compared with those analyzed by gas chromatography–mass spectrometry (GC-MS), a more conventional method used in the discrimination of fats and oils. Fatty acids extracted with 2-propanol were detected as deprotonated molecular ions ([M-H]-) in the ESI-MS spectra of the negative-ion mode. The composition obtained by ESI-MS corresponded to the data of the total ion chromatograms by GC-MS. The ESI-MS analysis discriminated the fats and oils within only one minute after starting the measurement. The detection limit for the analysis was approximately 10-10 g as a sample amount analyzed for one minute. This result showed that the ESI-MS analysis discriminated the fats and oils much more rapidly and sensitively than the GC-MS analysis, which requires several tens of minutes and approximately 10-9 g. Accordingly, the ESI-MS analysis was found to be suitable for a screening procedure for the discrimination of fats and oils.