Simultaneous Target Quantitation and Suspect Screening ofEnvironmental Contaminants in Sewage Sludge

Significance of Topic

Proper management of sewage sludge is critical due to its complex mixture of persistent environmental contaminants. Many toxicants originating from consumer products and their transformation products remain unregulated and insufficiently monitored, posing potential risks to ecosystems when biosolids are land applied.

Study Objectives and Overview

This work aimed to establish a combined targeted quantitation and suspect screening workflow for environmental contaminants in sewage sludge. Using an Agilent 1290 Infinity II LC coupled to a 6546 Q-TOF MS, 23 representative compounds were quantified while thousands of additional suspects were screened simultaneously in a single analysis.

Methodology and Instrumentation

Sample Preparation:

• A nonselective extraction protocol was applied to sludge samples collected from a California treatment plant to preserve a broad contaminant range.

Target Preparation:

• Twenty-three analytes—including pharmaceuticals, hormones, and pesticides—were spiked at calibration levels from 0.1 to 1000 µg/L in 20 % methanol–water.

Instrumentation:

• Fast LC gradients on the 1290 Infinity II system delivered high chromatographic resolution and throughput.
• The 6546 Q-TOF provided extended dynamic range, high mass resolution, and All Ions MS/MS acquisition.
• MassHunter Workstation with SureMass technology automated quantitation and suspect screening workflows.

Key Results and Discussion

Target Quantitation:

• Calibration exhibited linear or power-law responses down to low ppb levels.
• Retention time alignment, accurate mass measurement (<5 ppm), and isotope pattern matching provided high confidence quantitation.

Suspect Screening:

• Up to 4 856 compounds were monitored using a retention time prediction model derived from an environmental water PCDL.
• SANTE guidelines were applied to classify identifications as verified, requiring at least two ions, accurate mass, coelution, and isotope fidelity.

Benefits and Practical Applications

This integrated DIA workflow enables rapid quantitation of known priority contaminants while concurrently screening for emerging pollutants without additional runs. Retrospective data mining supports regulatory compliance, risk assessment, and management of biosolid applications.

Future Trends and Opportunities

Advancements in data-independent acquisition, expansion of high-resolution spectral libraries, and refined retention time prediction will enhance suspect identification. Machine learning integration may further streamline data review and reduce false positives, while retrospective analysis will remain valuable as new contaminants emerge.

Conclusion

The combination of high-throughput LC/Q-TOF instrumentation and automated DIA software provides a robust platform for simultaneous quantitation and suspect screening of sewage sludge contaminants. This approach increases analytical efficiency, expands contaminant coverage, and informs environmental monitoring and regulatory decision making.

References

1. Agilent Technologies. Endocrine-active contaminants in sludge, 2017.
2. Black et al. Sample preparation protocol review, in review.
3. Pyke et al. Agilent 6546 LC/Q-TOF configuration note, 2019.
4. SANTE/11813/2017 guidelines for pesticide analysis.
5. Agilent Technologies. PCDL library curation, 2017.
6. Berset et al. Environmental water screening method, 2016.