Large-scale generation of in silico based spectral libraries to annotate dark chemical space features in non-target analysis.

In this study, we develop and present an open-access LC-electrospray-HRMS/MS forward in silico fragmentation spectral library, based on the NORMAN Suspect List Exchange containing 120,514 chemicals, that can be used for level 3 annotations to support elucidation of the dark molecular features detected in environmental, exposomic, food safety, and forensic investigations. Using these forward generated in silico spectral libraries, several pollutants previously unreported in non-targeted workflows were discovered in groundwater for the first time through retrospective non-targeted screening analysis. Among these are xenobiotics such as hexafluoroacetone, hexazinone metabolites A, B, and C, and transformation products of triflusulfuron, fluazifop-butyl, triallate, and propiconazole. The generated in silico spectral libraries are freely available at https://doi.org/10.5281/zenodo.14854025 .