Reproducible trace analysis of PCBs in environmental matrices using triple quadrupole GC-MS/MS

Importance of the Topic

Polychlorinated biphenyls (PCBs) are persistent organic pollutants known for their chemical stability, lipophilicity, and toxicity. Their resistance to degradation and tendency to bioaccumulate pose significant environmental and human health risks, making sensitive and selective analytical methods critical for monitoring.

Objectives and Study Overview

This application note evaluates the performance of the Thermo Scientific TSQ 9610 triple quadrupole GC-MS/MS system, coupled with the TRACE 1610 GC and AI/AS 1610 autosampler, for trace-level determination of 30 PCB congeners in environmental water and soil matrices. Key aims include verifying chromatographic separation, calibration linearity, instrument detection limits, and long-term robustness.

Instrumentation Used

• Gas chromatograph: Thermo Scientific TRACE 1610 GC with instant-connect injector and detector modules
• Mass spectrometer: Thermo Scientific TSQ 9610 triple quadrupole with NeverVent Advanced EI ion source and XLXR detector
• Autosampler: Thermo Scientific AI/AS 1610 liquid sampler
• Column: TRACE TR-PCB 8 MS capillary column (50 m × 0.25 mm × 0.25 μm)
• Data system: Thermo Scientific Chromeleon 7.3 CDS supporting advanced isotope dilution quantitation

Applied Methodology

• Sample preparation: Aqueous (1 L) and solid samples (10 g dry weight) were extracted, cleaned via acid/base silica and alumina chromatography, and concentrated to 10–50 μL nonane
• Chromatographic conditions: Splitless injection at 280 °C, helium carrier at 1.2 mL/min, oven ramp from 90 °C to 330 °C over 25.2 min
• Detection mode: Timed-SRM using specific precursor-product ion transitions for each congener
• Calibration: Six-level 13C-labeled standard series (0.1–2000 ng/mL) with triplicate injections and isotope dilution quantitation
• Robustness evaluation: SmartTune performance checks and duplicate QC injections (1.0 ng/mL) every ten samples over 100 injections

Main Results and Discussion

• Chromatographic separation: Complete resolution in 21 min, including critical PCB-123/118 with 3% valley height; Gaussian peak shapes (As=1.2) for high-boiling congeners
• Linearity: Coefficients of determination (R²) >0.990 and AvCF %RSD <20% across the full 0.1–2000 ng/mL range
• Detection limits: Instrument detection limits of 3–19 fg on-column (equivalent to 0.15–0.95 pg/L in water and 0.015–0.095 ng/kg in soil); LOQ set at 0.05 ng/mL with ion ratios within ±15%
• Robustness: QC peak area RSDs <11% over 100 diverse environmental injections without maintenance or re-tuning

Benefits and Practical Applications

The demonstrated method offers high sensitivity and selectivity for routine monitoring of PCBs in environmental media, supporting regulatory compliance, risk assessment, and quality assurance in high-throughput laboratories.

Future Trends and Opportunities

Expansion of this approach may include analysis of additional persistent organic pollutants, integration with automated sample workflows, and coupling with high-resolution mass spectrometry for broader contaminant screening.

Conclusion

The Thermo Scientific TSQ 9610 GC-MS/MS, in combination with the TRACE 1610 GC and AI/AS 1610 autosampler, provides a robust, reliable, and highly sensitive platform for trace PCB analysis in environmental samples, meeting stringent detection, selectivity, and reproducibility requirements.

References

1. United States Environmental Protection Agency. (2022). Learn about Polychlorinated Biphenyls (PCBs).
2. Stockholm Convention on Persistent Organic Pollutants. (2001). Overview: Polychlorinated Biphenyls.
3. United States Environmental Protection Agency. (2010). Method 1668C: Chlorinated Biphenyl Congeners in Water, Soil, Sediment, Biosolids, and Tissue by HRGC/HRMS.