A key step in metabolomics research is the identification of metabolites. Searching accurate-mass LC/MS data against metabolite databases is a powerful technique for identifying metabolites. Due to the presence of isobaric masses such as compound isomers and diastereomers, database searching by mass alone is generally insufficient for positive identification. Public databases do not contain retention time information and thus there is no way to resolve the issue of isobaric masses. However, with Agilent Technologies’ METLIN Personal metabolite database, empirically derived, method-specific retention times (RTs) can be added to compounds in the database, creating an accurate-mass retention time (AMRT) database. Retention times then provide a second match criterion orthogonal to, and independent of, compound mass. Searching an AMRT database provides a narrower, more focused list of possible metabolite identities. This technical note discusses the addition of retention times to the METLIN Personal metabolite database and provides a faster batch approach for creating an AMRT database.
Searching accurate-mass LC/MS data against metabolite databases is a powerful technique for identifying metabolites, but public databases do not contain retention time information. This document explains how to use the Agilent METLIN Personal metabolite database and empirically derived, method-specific retention times to create an accurate-mass retention time (AMRT) database.
The guide outlines a workflow using MassHunter Qualitative Analysis software and Mass Profiler software to preprocess data from metabolite standards. This batch approach simplifies the assignment of standard matches and allows for the faster addition or updating of retention times in the METLIN software, providing a second match criterion orthogonal to compound mass.
Database searching by mass alone is generally insufficient for positive identification due to the presence of isobaric masses such as compound isomers and diastereomers.
Retention times can be added in a manual process or via a faster batch approach using Agilent MassHunter Mass Profiler software.
The metabolite standards and experiment samples must be analyzed using the exact same chromatographic method.