Submitted on September 11, 2006
Revised on October 3, 2006
Accepted on October 4, 2006
Rapid measurement of deuterium labeled long-chain fatty acids in plasma by HPLC-ESI-MS
Sébastien Gagné, Sheldon Crane, Zheng Huang, Chun Sing Li, Kevin P. Bateman, and Jean-François Lévesque
Medicinal Chemistry, Merck Frosst Canada Ltee, Kirkland, Quebec H9H 3L1
Corresponding Author: sebastien_gagne{at}merck.com
Imbalanced fatty acid metabolism contributes significantly to the increased incidents of metabolic disorders. Isotopes labeled fatty acids (2H, 13C) provide efficient means to trace the fatty acid metabolism in vivo. This study reports a new and rapid method for the quantification of deuterium labeled fatty acid in plasma by HPLC-MS. The sample preparation protocol developed required only hydrolysis, neutralization and quenching steps followed by HPLC-ESI-MS analysis in negative ion mode using single ion monitoring. d7-stearic acid (d7-C18:0) was synthesized in order to reduce matrix interference observed with d5 analogue, which improved LOD significantly, depending on the products analyzed. Linearity over 0.999 between LOD (100 nM) and 30 µM, accuracy over 90%, precision over 88% and adequate recovery in the dynamic range were obtained for d7-C18:0 and d7-C18:1. Upon the oral dosing of d7-C18:0 in rats, the parent compound and its desaturation and -oxidation products, d7-C18:1 and d7-C16:0, were circulating with a Cmax ranging from 0.6 to 2.2 µM with significant levels of d7-fatty acids detected up to 72h.