Poster Presentation HUPO 2019 - 18th Human Proteome Organization World Congress

Creating unique fragmentation in a flash:  small molecule structural elucidation using UVPD (#502)

Scott Peterman 1 , Seema Sharma 1 , Romain Huguet 1 , Vlad Zabrouskov 1 , Christopher Mullen 1 , Jean-Jacques Dunyach 1
  1. Thermo Fisher Scientific, San Jose, CA, USA

Structural elucidation of unknown small molecules using LC-MSn presents significant challenges due to the overwhelming structural diversity, and biotransformations.  Collision based methods generally results preferential dissociation, limiting the formation of structurally informative product ions.  This issue is particularly common for conjugated metabolites or fused-ring structures.  Recently, 213 nm UVPD sources were made commercially available on Orbitrap Tribrid mass spectrometers and used to dissociate a mixture of small molecule standards of varying structural classes on an LC-timescale.  The experiment consisted of standard data dependent acquisition with dynamic exclusion methods with both MS and UVPD MS/MS data acquired in the Orbitrap detector.  The standard mixture was analyzed using the same method except activation was done using HCD and CID for comparisons.  For those structures with increasing numbers of aryl rings and Pi bonds, UVPD significantly outperformed HCD/CID in both the number of product ions, and structural coverage and uniqueness.   To further evaluate the benefit of UVPD for small molecule structural elucidation, a series of flavonoids were extracted from commercial fruit smoothies and analyzed using the competitive dissociation methods.  The juice extract contained around 129 previously characterized flavonoids and conjugated metabolites from five different structural classes.  All data processing was automated based on database matching for known flavonoids, and prediction based on in silico fragmentation assumptions.