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Monitoring a natural autoxidation process of methyl linoleate by using GC-MS

Author

Ting Wang, University of the Pacific

Date of Award

2003

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Chemistry

First Advisor

Patrick R. Jones

First Committee Member

James W. Blankenship

Second Committee Member

Donald K. Wedegaertner

Abstract

The methyl ester of an unsaturated fatty acid, methyllinoleate was reacted with oxygen in a pressurized system at a controlled temperature. A natural autoxidation of methyl linoleate was observed without the addition of an initiating reagent. This autoxidation process could be used to mimic the course of lipid peroxidation, which is the major cause ofradical damage to living cells. The technology of GC-MS was employed to monitor the autoxidation of methyllinoleate.

Eight of the autoxidation products separated by GC column were identified by interpreting the corresponding EI ion mass spectra. The products from 9-alkoxy methyl linoleate radical were methyl octanate, 2,4-decadienal, nonanoic acid, 9-oxo-methyl ester, and its further oxidation product, nonanedioic acid, monomethyl ester. All of them formed through a pathway of beta-cleavage. The products from 13-alkoxy methyl linoleate radical were tridecanoic acid, 9, 11-diene-13-oxo-methyl ester, hex anal, and its further oxidation product, hexanoic acid. They were also formed through a mechanism of beta-cleavage. The fourth product from 13-alkoxy methyllinoleate radical was 13-keto-9, 11-octadecadienoic acid, methyl ester, which was obtained through a pathway of keto formation. Observation of their concentrations in the samples at different autoxidation periods revealed the time-course of formation of these products.

Pages

122

Recommended Citation

Wang, Ting. (2003). Monitoring a natural autoxidation process of methyl linoleate by using GC-MS. University of the Pacific, Thesis - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/586