Using suspect and non-targeted analysis (NTA) by high-resolution mass spectrometry to gain deeper insight into organic contamination of freshwater sediments

Synthetic organic micropollutants produced and used worldwide ultimately find their way into aquatic ecosystems through wastewater discharge and surface runoff. This contamination can migrate into sediment, where it forms archives. The potential toxicity and persistency of these micropollutants makes it crucial to monitor them. Monitoring efforts have historically used GC-MS to study well-known molecules like polychlorinated biphenyls (PCBs) or organochlorine pesticides. However, growing concern around emerging contaminants has spurred efforts to use LC-HRMS analysis to detect and identify a broader panel of small synthetic molecules via non-targeted analysis (NTA). Here we compared several sample preparation methods using accelerated solvent extraction (ASE) and ultrasound-assisted extraction (UAE) for non-targeted analysis. UAE was applied on suspended particulate matter from the Rhône River, followed by LC-ESI-QTOF analysis. The dual complexity of HRMS data and sediment matrix poses a challenge for data processing. We developed, combined and discussed open-source software programs (MZmine3, jHRMSToolBox and HaloSeeker 2.0). Even though most of identified molecules are natural and produced by plants or animals, suspect and non-target approaches allowed identifying pharmaceuticals, hormones, personal care products, pesticides, plastic and rubber additives, PFAS, flame-retardants, and other industrial molecules. This work demonstrates valuable insight gained by exploring emerging micropollutants in sediments.