The METLIN Metabolite and Chemical Entity Database[1][2][3] is the largest repository of experimental tandem mass spectrometry[4] and neutral loss[5] data acquired from standards.
[11] All tandem mass spectrometry data comes from the experimental analysis of standards at multiple collision energies and in both positive and negative ionization modes.
Since its initial implementation in the early 2000s,[2] the freely available METLIN website has collected comments and suggestions for improvements from users in the biotechnology, pharmaceutical and academic communities ultimately resulting in functionally useful technology for metabolomics as well as hundreds of thousands of other molecular entities.
Also, METLIN has been used to create a novel multiple reaction monitoring (MRM) library of precursor to fragment ion transitions.
[13] The METLIN-MRM transition repository for small-molecule quantitative tandem mass spectrometry was designed to facilitate data sharing across different instruments and laboratories.