EAS: Analysis of PAHs and PCBs in multiple matrices using GC-MS and GC-MS/MS

Importance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are persistent environmental pollutants with high toxicity and bioaccumulative potential. Accurate and efficient analysis of these compounds is essential for environmental monitoring, regulatory compliance, and public health protection.

Objectives and Overview of the Study

• Assess a GC-MS method for quantifying PAHs in water and soil matrices according to EPA Method 8270E.
• Evaluate a GC-MS/MS approach for targeted PCB analysis using SRM on a TRACE TR-PCB column.
• Demonstrate robustness, sensitivity, and compliance-friendly workflows for high-throughput laboratories.

Methodology and Instrumentation

• Sample preparation involved spiking blank water and soil matrices at relevant concentration levels, followed by solvent extraction and clean-up protocols.
• PAH analysis used a gas chromatograph coupled to a single quadrupole mass spectrometer with in-sequence DFTPP tuning every 12 hours to meet EPA 8270E requirements.
• PCB analysis employed GC-MS/MS on a triple quadrupole system with a TRACE TR-PCB column, monitoring compound-specific SRM transitions and collision energies for 209 congeners and isotopically labeled standards.
• Calibration strategies covered wide dynamic ranges using single or multiple curves as needed, with routine QC checks and automated report generation for compliance.

Main Results and Discussion

• PAH method achieved baseline separation of target isomers within 14.5 minutes, minimal peak broadening (0.022–0.034 min), and avoided isobaric interferences through mass selectivity.
• Calibration linearity spanned 2.5–20 000 ng/mL with average relative response factor variation <15 % (R² >0.99), allowing trace to high-level quantitation on a single curve.
• Robustness tests showed %RSD <10 % for 133 consecutive injections over 52 hours without GC or MS maintenance; method detection limits ranged from 0.5 to 7.6 pg on column.
• PCB workflow separated critical pairs (e.g., PCB-123/118) in ~21 minutes with resolution Rs≈3 %, linearity over 0.1–2000 ng/mL (R² >0.99), and IDLs of 3–19 fg on column (LOQ=0.05 ng/mL).
• Extended robustness exceeded 100 injections without maintenance or re-tuning, and QC absolute peak area RSDs remained below 10 % across the sequence.

Benefits and Practical Applications

• High throughput analysis for environmental, QA/QC, and regulatory laboratories.
• Reduced instrument downtime via extended maintenance intervals and automated compliance reporting.
• Comprehensive quantitation over broad concentration ranges with single calibration schemes.
• Applicability to diverse matrices including water, soil, and other environmental samples.

Future Trends and Opportunities

• Integration of automated sample preparation and online extraction to further increase throughput.
• Expansion of targeted workflows to include emerging contaminants and transformation products.
• Adoption of high-resolution MS and advanced data processing for non-target screening.
• Implementation of real-time monitoring platforms and miniaturized GC-MS systems for field applications.

Conclusion

The described GC-MS and GC-MS/MS methods deliver fast, sensitive, and reproducible analysis of PAHs and PCBs, meeting stringent EPA requirements while minimizing maintenance and maximizing instrument uptime. These workflows offer robust solutions for environmental monitoring and compliance.