Identification of LC-HRMS nontarget signals in groundwater after source related prioritization

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Hydrogeology

Background:

• Groundwater is a critical drinking water source.
• The presence and impact of organic micropollutants (MPs) in groundwater are not fully understood.
• Comprehensive assessment of MPs in groundwater is essential for water quality management.

Purpose of the Study:

• To comprehensively investigate organic micropollutants in Swiss groundwater.
• To identify and quantify MPs originating from urban and agricultural sources.
• To develop and apply advanced analytical methods for MP detection and identification.

Main Methods:

• Liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS) was employed.
• Samples from 60 sites were classified by urban/agricultural influence using 498 target compounds.
• Nontarget and suspect screening, coupled with automated structure elucidation (MetFrag, SIRIUS4/CSI:FingerID), were utilized.

Main Results:

• A significant fraction of MP concentrations could not be attributed to known targets.
• Twelve novel nontargets and eleven suspects were unequivocally identified, including 13 previously unreported groundwater pollutants.
• Thirteen new pollutants were identified in groundwater, such as 2,5-dichlorobenzenesulfonic acid and transformation products of amlodipine and metolachlor.
• One site showed significantly higher contamination, with identified site-specific MPs including chlorendic acid.

Conclusions:

• Source-related prioritization is an effective strategy for identifying MPs in groundwater.
• Advanced analytical techniques reveal a wider range of MPs than previously known.
• The study identified previously unreported pollutants in groundwater, underscoring the need for ongoing monitoring and risk assessment.