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

## TL;DR

This paper introduces a large in silico spectral library to help identify unknown chemicals in environmental and other non-targeted analyses.

## Contribution

A novel open-access in silico fragmentation spectral library for non-targeted analysis of dark chemical space features.

## Key findings

- The library enabled the discovery of previously unreported pollutants in groundwater.
- Xenobiotics like hexafluoroacetone and transformation products of several chemicals were identified for the first time.
- The library supports level 3 annotations in environmental, exposomic, food safety, and forensic investigations.

## Abstract

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.

The online version contains supplementary material available at 10.1007/s00216-025-06034-4.