Analyzing Wastewater Effluents for PAH’s and PBDE’s Using the Agilent 7000 Triple Quadrupole GC/MS

Significance of the Topic

Polyaromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs) are prioritized contaminants under European water quality legislation due to their persistence, bioaccumulation potential, and toxicity. Monitoring these substances in wastewater effluents is critical for assessing treatment performance, protecting aquatic life, and ensuring compliance with Environmental Quality Standards set by the EU Water Framework Directive and its daughter directives.

Objectives and Study Overview

This study aimed to develop and validate a streamlined analytical workflow for the simultaneous determination of 8 PAHs and 6 PBDEs in wastewater using a single liquid–liquid extraction, minimal cleanup, and triple quadrupole gas chromatography–mass spectrometry (GC/MS/MS). The method was designed to meet the stringent detection and reporting limits of the UK Chemical Investigations Programme (CIP) for both microgram and nanogram per liter concentrations.

Methodology and Instrumentation

Sample preparation involved:

• Collection of 500 mL wastewater samples in amber flasks
• Ammonia addition and dilution to optimize extraction pH
• Overnight rolling extraction with hexane for analyte partitioning
• Concentration of the organic phase under nitrogen to 250 µL

Instrumentation details:

• Agilent 7890A GC system with multimode inlet in solvent vent mode, 4 mm glass-bead liner
• HP-5 phenyl-methyl siloxane column (30 m × 0.25 mm, 0.25 µm)
• Carrier gas helium at constant velocity (30 cm/s)
• Oven program: 25 °C/min ramp to 300 °C, 8.4 min hold; total run time 20 min
• Agilent 7000B Triple Quadrupole MS in electron ionization, multiple reaction monitoring (MRM)
• Collision gas nitrogen; quench gas helium; source at 300 °C; quadrupoles at 230 °C

Main Results and Discussion

The method achieved baseline separation of most analytes in under 20 minutes, with two PAH isomers partially resolved. Calibration curves for all compounds showed excellent linearity (R2 > 0.999). Reporting limits ranged from 0.06 to 3.0 ng/L, surpassing CIP analytical quality control requirements. Chromatograms demonstrated clear quantifier and qualifier ion transitions, ensuring selectivity and sensitivity in complex effluent matrices.

Benefits and Practical Applications

The proposed approach offers:

• High throughput with a single extraction and no solvent exchange
• Minimal cleanup steps, reducing analysis time and solvent consumption
• Reproducible detection at ultra-trace levels suitable for regulatory monitoring
• Applicability to crude sewage, process streams, final effluents, and sludge extracts

Future Trends and Opportunities

Advances in GC/MS/MS technology and sample automation may further reduce detection limits and improve lab efficiency. Integration with high-resolution mass spectrometry could expand the scope to emerging contaminants. Automation of sample preparation and data processing will enhance reproducibility and throughput for large-scale monitoring programs.

Conclusion

The developed GC/MS/MS method on the Agilent 7000 series delivers sensitive, reliable, and efficient analysis of PAHs and PBDEs in wastewater effluents. Its single-step extraction and robust quantification meet or exceed regulatory requirements, supporting environmental monitoring and risk assessments.

References

• Pollutants in Urban Waste Water and Sewage Sludge, European Commission report on sludge pollutants summary