Simultaneous eicosanoid profiling and identification by liquid chromatography and hybrid triple quadrupole-linear ion trap mass spectrometry for metabolomic studies in human plasma

Eicosanoids play a key role in many physiological and pathological processes and might therefore serve as interesting diagnostic targets. Methods for the analysis of arachidonic acid metabolites in cells and body fluids require high sensitivity and specificity because of the very low concentrations, similar chemical structures and short half-lives of these metabolites. We established a mass spectrometric method for the simultaneous identification and quantification of arachidonic acid metabolites in human plasma samples using solid phase extraction followed by liquid chromatography (LC) and hybrid triple quadrupole-linear ion trap (QqLIT) mass spectrometry. Quantitative analysis was performed using the 4000 QTrap tandem mass spectrometer in multiple reaction monitoring (MRM) mode. As part of an independent data acquisition experiment MRMs were used as survey scans, which dependently triggered enhanced product ion (EPI) scans. Compound identification was carried out by library search using a library based on EPI spectra of standard components (prostaglandins, thromboxanes, leukotrienes and isoprostanes). The newly developed compound library enables the verification of known and structural elucidation of unknown eicosanoid metabolites in human plasma. In conclusion, our mass spectrometric method allows the simultaneous identification and quantification of arachidonic acid metabolites in one single LC-MS/MS run.