Development of a sensitive and quantitative method for the identification of two major furan fatty acids in human plasma

This paper focuses on the establishment of an accurate and sensitive quantitation method for analysis of furan fatty acids. Particularly, the sensitivity of GC-MS and UPLC-ESI-MS/MS was compared for the identification and quantification of furan fatty acids. Different methylation methods were tested with respect to GC-MS analysis. Special attention needs to be paid to the methylation of furan fatty acids as acidic catalysts might lead to the degradation of furan ring. GC-MS analysis in full scan mode demonstrated that the limit-of-quantitation (LOQ) was 10 muM. UPLC-ESI-MS/MS in multiple reaction monitoring (MRM) mode displayed a higher detection sensitivity than GC-MS. Moreover, identification of furan fatty acids with charge-reversal derivatization was tested in positive mode with two widely used pyridinium salts. Unexpectedly, significant oxidation was observed using N-(4-aminomethylphenyl) pyridinium (AMPP) as a derivatization agent. The formed 3-acyl-oxymethyl-1-methylpyridinium iodide (AMMP) derivatized by 2-bromo-1-methylpyridinium iodide and 3-carbinol-1-methylpyridinium iodide improved the sensitivity more than 2000 fold, compared with non-derivatization in negative mode by UPLC-ESI-MS/MS. This charge reversal derivatization enabled the targeted quantitation of furan fatty acids in human plasma. Thus, it is anticipated that this protocol could greatly contribute to the clarification of pathological mechanisms related to furan fatty acids and their metabolites.