title: Consensus structure elucidation combining GC/EI-MS, structure generation, and calculated properties.
abstract: This article explores consensus structure elucidation on the basis of GC/EI-MS, structure generation, and calculated properties for unknown compounds. Candidate structures were generated using the molecular formula and substructure information obtained from GC/EI-MS spectra. Calculated properties were then used to score candidates according to a consensus approach, rather than filtering or exclusion. Two mass spectral match calculations (MOLGEN-MS and MetFrag), retention behavior (Lee retention index/boiling point correlation, NIST Kovat's retention index), octanol-water partitioning behavior (log K(ow)), and finally steric energy calculations were used to select candidates. A simple consensus scoring function was developed and tested on two unknown spectra detected in a mutagenic subfraction of a water sample from the Elbe River using GC/EI-MS. The top candidates proposed using the consensus scoring technique were purchased and confirmed analytically using GC/EI-MS and LC/MS/MS. Although the compounds identified were not responsible for the sample mutagenicity, the structure-generation-based identification for GC/EI-MS using calculated properties and consensus scoring was demonstrated to be applicable to real-world unknowns and suggests that the development of a similar strategy for multidimensional high-resolution MS could improve the outcomes of environmental and metabolomics studies.
authors.affiliation: UFZ-Helmholtz Centre for Environmental Research, Department of Effect-Directed Analysis, Permoserstrasse 15, D-04318 Leipzig, Germany. emma.schymanski@eawag.ch
authors.forename: Emma L
authors.initials: EL
authors.lastname: Schymanski
authors.forename: Christine M J
authors.initials: CM
authors.lastname: Gallampois
authors.forename: Martin
authors.initials: M
authors.lastname: Krauss
authors.forename: Markus
authors.initials: M
authors.lastname: Meringer
authors.forename: Steffen
authors.initials: S
authors.lastname: Neumann
authors.forename: Tobias
authors.initials: T
authors.lastname: Schulze
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wolf
authors.forename: Werner
authors.initials: W
authors.lastname: Brack
mesh_terms: D004785:Environmental Pollutants / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D048088:Informatics / Q000379:methods*; D008968:Molecular Conformation; D013816:Thermodynamics
chemical_list: D004785:Environmental Pollutants