Routine, robust analysis of PAHs and PCBs in soil by single quadrupole GC-MS

Significance of the Topic

Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that pose serious environmental and health risks. Their chemical stability and tendency to bioaccumulate necessitate reliable analytical methods for routine soil monitoring.

Study Objectives and Overview

This study demonstrates the performance of the Thermo Scientific™ ISQ™ 7000 single quadrupole GC-MS system with an ExtractaBrite EI source for robust, high-throughput analysis of PAHs and PCBs in soil using a modified QuEChERS extraction workflow.

Methodology and Instrumentation

A QuEChERS protocol was applied to soil samples spiked with native and 13C-labeled standards. Analysis was performed on a TRACE™ 1310 GC coupled to an ISQ™ 7000 MS with Vacuum Probe Interlock (VPI) and ExtractaBrite source. Key parameters and components:

• Column: TraceGOLD™ TG-5SilMS, 30 m × 0.25 mm × 0.25 µm
• Injection: 1 µL splitless with single-taper glass wool liner
• Detection: timed-SIM mode, m/z range 50–550
• Software: Chromeleon CDS for control, data processing, and reporting
• Calibration: twelve-level curve for 45 analytes; low-level QC at 40 pg/µL

Main Results and Discussion

• Peak area repeatability for 115 consecutive soil extract injections remained below 15% RSD, demonstrating five days of maintenance-free operation.
• Over a 320-injection sequence (including >250 soil samples), response factor RSDs for all target compounds were ≤11% without column trimming or source cleaning.
• Ion ratio deviations in low-level QC injections stayed within ±15% tolerance over two weeks of continuous analysis.
• Only septa replacement occurred every 100 injections; no MS tuning, liner changes, or additional maintenance were required.

Benefits and Practical Applications

• High throughput with minimal instrument downtime supports large-scale environmental monitoring.
• Robust performance reduces maintenance costs and increases laboratory productivity.
• Accurate trace-level quantification and stable ion ratios facilitate regulatory compliance.

Future Trends and Potential Uses

• Automated sample preparation to further enhance throughput and reproducibility.
• Integration of high-resolution or tandem MS for greater specificity in complex matrices.
• Field-deployable and real-time systems for on-site environmental screening.
• Adoption of green extraction solvents and microextraction techniques to reduce solvent consumption.

Conclusion

The Thermo Scientific ISQ 7000 VPI GC-MS platform, combined with a modified QuEChERS method, delivers consistent, long-term performance for routine PAH and PCB soil analysis. Its demonstrated stability and low maintenance requirements make it an ideal solution for high-volume environmental testing laboratories.

References

1. European Chemicals Agency. Guidance on information requirements and chemical safety assessment, Part C: PBT/vPvB. Available online; accessed May 8, 2018.
2. Lamb A, Ladak A, English C, Rattray C, Cojocariu C. Simultaneous routine GC-MS analysis of PCBs, PAHs, and derivatives in soil using modified QuEChERS methodology. Thermo Scientific Application Note 10720, 2019.