Mass spectrometry-based metabolomics

untargeted. Targeted metabolomics focuses on a subset of metabolites involved in one or more pathways; the chemical identities of metabolites to be measured are known, authentic standards are available in these studies. The goal of untargeted metabolomics is to observe global metabolite profiling differences between sample types, experiments are designed to maximise the coverage of metabolites. A significant bottleneck in this approach is the identification of metabolites. Here, we provide a brief overview of the gas chromatography mass spectrometry (GC-MS) and liquid chromatography mass spectrometry (LC-MS) instrumentation platforms used in untargeted metabolomics studies. Two other mass spectrometry based techniques, direct infusion mass spectrometry (DIMS) and capillary electrophoresis mass spectrometry (CE-MS), have been reviewed elsewhere and will not be discussed here.