Liquid chromatography coupled to mass spectrometry (LC-MS)-based metabolomics and lipidomics offers invaluable tools to qualitatively and quantitatively study biological systems. Historically, unbiased (or discovery) analysis has been performed independently of targeted, quantitative analysis such as multiple reaction monitoring (MRM). These practices have been aptly carried out based on technical limitations of each assay. The wide mass scanning ranges typical of discovery approaches limit assay sensitivity, while targeted methods that improve analyte detection do not acquire data on ions not included in the targeted assay design. Recent improvements to quadrupole-Orbitrap technology have improved both scan speed as well as sensitivity, thus making these instruments more robust. By combining the improved robustness and coverage with stable isotope dilution (SID) techniques, advantages of the separate assays can now be realized in a single run, thereby improving the throughput of this type of analysis.
Keywords: Absolute quantification; Bile acids; Gradient; High-throughput; Mass spectrometry; Oxylipids; Untargeted metabolomics.