Improved metabolite characterization by liquid chromatography- Tandem mass spectrometry through electron impact type fragments from adduct ions

Using a chimeric collision cell mounted on a quadrupole time-of-flight platform, collision induced dissociation (CID) and electron induced dissociation (EID) were investigated for the LC-MS analysis of low molecular weight compounds including drugs and endogenous metabolites. Compared to CID, EID fragmentation of the [M+H](+) species (10-20 eV) from standard compounds resulted in additional specific and informative fragments, mostly due to neutral losses and, in some cases due to ring openings. Some analytes, for example reserpine and vinpocetine, provided characteristic [M broken vertical bar H]center dot(2+) species. For most analytes for sodium and potassium adducts and multimers a radical cation M center dot(+)thorn and electron impact type fragments were observed in the EID spectra, providing the opportunity to use EI libraries to support metabolite identification. EID opens the possibility to get structural information from adduct ions which is often not the case with CID. EID enabled the putative characterization of two metabolites in rat urine as glucuronides of 5,6-dihydroxyindole based on EID fragmentation of the potassium adducts. (C) 2021 The Author(s). Published by Elsevier B.V.

Automated summary

The study investigated CID and EID fragmentation mechanisms in LC-MS analysis, revealing that EID is superior to CID in generating specific and informative fragments for metabolite identification. EID also has the capability to provide structural information from adduct ions, offering the possibility for new metabolite characterization.