Screening Environmental Samples for a Diverse Range of Compounds With Accurate Mass LC-MS and an Integrated Scientific Information System

Significance of the Topic

The widespread presence of pharmaceuticals and personal care products (PPCPs) in environmental water demands screening methods capable of detecting a diverse array of trace contaminants in a single analysis run. High-resolution mass spectrometry (HRMS) with comprehensive data acquisition addresses limitations of targeted tandem MS by enabling the detection of unlimited compound lists with reduced false positives.

Objectives and Study Overview

• Demonstrate screening of local well water samples for over 1000 PPCPs, pesticides, and drugs of abuse using HRMS and an integrated informatics platform.
• Evaluate a mixed-mode solid phase extraction (SPE) protocol for acidic, basic, and neutral analytes.
• Assess the impact of retention time and fragment ion criteria on false detection rates.

Methodology and Instrumentation

A mixed-mode SPE protocol (Oasis MAX and MCX) provided a 1000-fold enrichment from 1 L water samples. Separation employed UPLC on an ACQUITY UPLC I-Class System with an HSS C18 column (2.1×150 mm, 1.8 µm) at 50 °C and a 15 min gradient. Detection used a Xevo G2-S QTof Mass Spectrometer in ESI+ mode, collecting low and elevated collision energy data (MSE) for simultaneous precursor and fragment information. Data processing and compound identification utilized UNIFI with a Toxicology Library of over 1000 entries, applying mass accuracy (5 ppm), retention time (±0.5 min), and fragment ion criteria.

Main Results and Discussion

• Of 35 spiked PPCPs, none were present as incurred residues; four unexpected compounds were identified using combined retention time and fragment ion criteria.
• Calibration curves for analytes (e.g., cocaine) demonstrated reliable quantification at ng/L levels.
• Incorporating retention time tolerance and fragment ion matching reduced false positives by over 65%, while maintaining low false negative rates.

Benefits and Practical Applications

• High-throughput, non-targeted screening of a large compound library in routine laboratory settings.
• Accurate mass and fragment data in a single injection improve detection confidence.
• Customizable identification parameters in UNIFI streamline data review and reduce analyst workload.

Future Trends and Applications

• Expansion of chemical libraries to include emerging contaminants and metabolites.
• Advanced chromatographic techniques and higher resolution instruments for enhanced separation.
• AI-driven data analysis to further decrease false detections and automate interpretation.

Conclusion

The integration of HRMS with UPLC/MSE and an informatics platform enables comprehensive, reliable screening of environmental water for diverse trace contaminants. The approach demonstrated efficient detection and quantification with minimized false positives, supporting robust environmental monitoring workflows.

References

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