Polyaromatic hydrocarbon analysis by gas chromatography mass spectrometry using HeSaver-H2Safer technology

Importance of the Topic

Polyaromatic hydrocarbons (PAHs) are widespread environmental pollutants formed by incomplete combustion of organic materials. Many PAHs are potent carcinogens or endocrine disruptors at low concentrations, requiring highly sensitive and reliable analytical methods to comply with environmental regulations and safeguard public health.

Objectives and Study Overview

This study evaluates the performance of the Thermo Scientific HeSaver-H2Safer carrier gas saving technology integrated into an iConnect SSL injector for PAH analysis by GC-MS. The goal was to compare injection repeatability, sensitivity, linearity, and peak shape with a standard SSL injector under U.S. EPA Method 8270E conditions, while dramatically reducing helium consumption.

Methodology and Instrumentation

• Instrumentation: Thermo Scientific TRACE 1610 gas chromatograph with HeSaver-H2Safer-enabled iConnect SSL injector; Thermo Scientific ISQ 7610 single quadrupole mass spectrometer.
• Column: Thermo Scientific TG-PAH capillary column (30 m × 0.25 mm × 0.10 µm).
• Carrier gas strategy: Helium limited to column flow; inexpensive gas (nitrogen or argon) used for inlet pressurization and analyte transfer.
• Method: U.S. EPA Method 8270E for semivolatile organic compounds.

Key Results and Discussion

• Injection repeatability: Peak area RSD < 7% (split) and < 15% (splitless) at the lowest calibration level (2.5 ng/mL).
• Linearity: Calibration curves for 18 PAHs showed R² > 0.997 across four orders of magnitude.
• Instrument detection limits: Comparable to standard SSL injector, ranging from 0.22 to 0.84 ng/mL.
• Peak shape: Asymmetry maintained within acceptable limits (e.g., fluoranthene asymmetry 1.15 after 200 injections).
• Helium savings: Estimated helium cylinder life extended threefold versus standard injector; significant cost reduction.

Benefits and Practical Applications

• Maintains existing validated methods without reoptimization.
• Reduces helium consumption dramatically during operation and idle periods.
• Preserves GC-MS performance in terms of sensitivity, linearity, and chromatographic resolution.
• Enables rapid gas replacement in the column inlet, facilitating easier maintenance and protecting column integrity.
• Offers cost savings and enhanced operational continuity amid global helium supply constraints.

Future Trends and Potential Applications

Broader adoption of carrier gas saving technologies is expected across environmental, food safety, and industrial laboratories. Integration with laboratory information systems and further optimization for alternative gases (e.g., hydrogen) may expand applications to other semi-volatile compounds. Development of predictive tools and real-time monitoring could further enhance resource efficiency.

Conclusion

The HeSaver-H2Safer technology provides a straightforward upgrade to existing GC-MS systems, cutting helium usage by up to two thirds while maintaining analytical performance for PAH analysis. Laboratories can preserve validated methods, achieve cost savings, and mitigate helium supply risks without compromising data quality.

References

1. Scollo G, Parry I, Cavagnino D. Thermo Fisher Scientific Technical Note 001218: Addressing Gas Conservation Challenges When Using Helium or Hydrogen as GC Carrier Gas; 2022.
2. United States Environmental Protection Agency. Method 8270E: Semivolatile Organic Compounds by Gas Chromatography/Mass Spectrometry, Revision 6; June 2018.
3. Calaprice C, Pike B, Riccardino G, Ladak A, Silcock P. Thermo Fisher Scientific Application Note 000455: Analysis of Multiple Matrices with a Single Calibration Curve for PAHs Using ISQ 7610 GC-MS Following EPA Method 8270; 2021.
4. Thermo Fisher Scientific. Helium Saver Calculator Tool; 2022.