Environmental analysis of polychlorinated biphenyls (PCBs) at reduced running costs using hydrogen as carrier gas

Significance of the Topic

Polychlorinated biphenyls (PCBs) are highly persistent organic pollutants that pose health and environmental risks due to their toxicity and bioaccumulation. Reliable, cost-effective analytical methods are essential to monitor PCB contamination in water, soil, sediment and biota. Switching from helium to hydrogen carrier gas can reduce laboratory operating costs and address current helium supply challenges.

Objectives and Overview

This study evaluates the performance of a Thermo Scientific TRACE 1610 GC coupled to a TSQ 9610 triple quadrupole mass spectrometer for PCB analysis using hydrogen versus helium carrier gas. Acceptance criteria were based on US EPA Method 1668. Key aims include assessment of chromatographic resolution, detection limits, ion ratio stability and method linearity under both carrier gas conditions.

Methodology and Instrumentation

The GC-MS/MS method was adapted from a previous application note with minor changes summarized in the following list

• Carrier gas flow set at 1.2 mL/min for hydrogen or equivalent helium flow
• Splitless injection with HeSaver-H2Safer inlet and 50 mL/min split flow of nitrogen
• TRACE TR-PCB 8 MS column, 50 m × 0.25 mm, 0.25 μm film thickness
• Oven program unchanged from the original method to enable direct comparison

Used Instrumentation

• Thermo Scientific TRACE 1610 gas chromatograph
• Thermo Scientific TSQ 9610 triple quadrupole mass spectrometer
• HeSaver-H2Safer splitless injector module
• Thermo Scientific TRACE TR-PCB 8 MS capillary column
• AEI source operated at 350 °C and emission current of 10 μA

Main Results and Discussion

Chromatographic resolution of the critical PCB-123 and PCB-118 pair was maintained with hydrogen carrier gas, achieving baseline separation. Instrumental detection limits for most congeners were below 20 fg on-column with hydrogen, matching helium performance. Ion ratio reproducibility at 0.05 ppb showed deviations under 12 percent for all analytes. The method demonstrated excellent linearity from 0.1 to 2000 ppb, with R2 ≥ 0.9998 and average response factor RSD below 3 percent.

Benefits and Practical Applications

• Significant reduction in carrier gas costs by using hydrogen instead of helium
• Safe hydrogen operation without additional oven sensors via HeSaver-H2Safer technology
• Comparable sensitivity, selectivity and robustness for PCB monitoring
• Compatibility with regulatory methods such as US EPA Method 1668

Future Trends and Potential Applications

Adoption of hydrogen carrier gas is expected to expand across environmental laboratories, supported by on-site hydrogen generators. The approach may be extended to other persistent organic pollutants and complex matrices, leveraging advanced GC-MS/MS systems for high-throughput monitoring and compliance testing.

Conclusion

Hydrogen carrier gas, in combination with a HeSaver-H2Safer inlet and a TSQ 9610 triple quadrupole mass spectrometer, provides a viable alternative to helium for PCB analysis. This configuration maintains analytical performance while reducing operational costs and reliance on helium supply.

References

• US EPA Method 1668 Chlorinated Biphenyl Congeners in Water, Soil, Sediment, Biosolids, and Tissue by HRGC/HRMS, 2010
• Stockholm Convention on Persistent Organic Pollutants, PCB Overview, 2001
• Thermo Fisher Scientific Application Note AN000561 Reproducible Trace Analysis of PCBs in Environmental Matrices using GC-MS/MS
• Thermo Fisher Scientific Application Note AN002549 Environmental Analysis of PCBs with Reduced Running Costs