METLIN-MRM/XCMS-MRM

METLIN-MRM (http://metlin.scripps.edu/), is a public multiple-reaction monitoring (MRM) transition repository for small-molecule quantitative tandem mass spectrometry. This platform provides MRM transitions for thousands of molecular standards and facilitates data sharing across different instruments and laboratories. It is coupled with XCMS-MRM (http://xcmsonline-mrm.scripps.edu/) to facilitate targeted lipidomic and metabolomic analyses. METLIN-MRM library is a compendium of small-molecule transitions for MRM MS. Three different types of transitions are available: (i) traditional experimentally optimized (EO) transitions, (ii) computationally optimized (CO) experimental transitions and (iii) public repository (PR) transitions. . XCMS-MRM focuses on the information from all the transitions for a given compound and uses this information to detect the peak of interest efficiently. Unimodality through an isotonic regression is applied to the final chromatographic-peak profile to improve the quality of the extracted peak, to ensure that only one peak is integrated and thus minimize the interference of noise and low-concentration and co-eluted peaks.