Simultaneous Targeted Quantitation and Suspect Screening of Environmental Contaminants in Sewage Sludge

Significance of the topic

This study addresses the growing need for comprehensive analysis of persistent and emerging contaminants in sewage sludge, a complex matrix used in land applications. Combining targeted quantitation with suspect screening helps laboratories meet stringent environmental regulations and uncover new toxicants that may impact ecosystems.

Objectives and study overview

The aim is to develop and validate a workflow using the Agilent 6546 LC/Q-TOF system for simultaneous high-accuracy quantitation of regulated compounds and wide-scope suspect screening of thousands of emerging environmental contaminants in sewage sludge samples, enabling both real-time monitoring and retrospective data mining.

Methodology and instrumentation

Sample preparation was deliberately nonselective to retain a broad range of analytes. Seventeen target compounds were spiked into sludge matrix at levels from 0.1 to 1,000 ppb. Instrumentation included an Agilent 1290 Infinity II UHPLC with a Poroshell EC-C18 column (2.1 × 100 mm, 1.9 µm), 0.4 mL/min gradient (0.1% formic acid or 1 mM ammonium fluoride mobile phase depending on ionization mode), 1 µL injection. The Agilent 6546 LC/Q-TOF operated with Jet Stream source, All Ions DIA from 50 to 1,050 m/z at 8 Hz, collision energies 0/10/20/40 V. Data were acquired in MassHunter Acquisition and processed with SureMass and MassHunter Quantitative Analysis including the LC Screener tool.

Main results and discussion

Quantitation of 23 spiked surrogates demonstrated linear dynamic ranges up to 1,000 ppb (R2 > 0.99), limits of detection down to 0.1 ppb, and accurate calibration with weighted regression. Calibration curves for all targets showed consistent response and fit. Suspect screening against a library of 4,856 curated compounds yielded 18 verified positives, 159 requiring review, and 3,998 negatives in positive mode; 8 verified, 47 review, and 1,267 not detected in negative mode. Retention time prediction models further refined the suspect list, reducing false positives and review workload.

Benefits and practical applications of the method

This unified workflow enables high-throughput environmental monitoring laboratories to obtain regulatory-grade quantitative data for known toxins while concurrently screening for thousands of potential contaminants in a single injection, saving time, resources, and enhancing response to emerging threats.

Future trends and applications

Expanding compound databases with predicted retention times and MS/MS spectra, integrating QSAR toxicity predictions, and enhancing retrospective data analysis will further strengthen non-target screening capabilities. Adoption of similar workflows across water, soil, and biota matrices will support proactive environmental risk assessments.

Conclusion

The combined targeted quantitation and suspect screening approach using the Agilent 6546 LC/Q-TOF delivers sensitive, accurate measurement of regulated compounds and broad surveillance of emerging contaminants in sewage sludge, streamlining environmental analysis and enabling discovery of new toxicants.

Reference

• Agilent Technologies. SureMass Technical Overview; publication 5991-8048EN, 2017.
• European Commission Directorate-General for Health and Food Safety. SANTE/11813/2017, 2017.
• Berset J. D.; Rennie E. E.; Glauner T. Agilent Technologies; publication 5991-6627EN, 2016.
• Rennie E. E. et al. Personal Compound Database and Library Guide; Agilent Technologies publication 5991-8580EN, 2017.
• Black G. P.; Anumol T.; Young T. M. Analytical methods for endocrine disruptors in sewage sludge; in preparation, 2019.