Analysis of Polynuclear Aromatic Hydrocarbons (PAHs) in Wastewater by GC/MS

Importance of the Topic

Polynuclear aromatic hydrocarbons (PAHs) are widespread environmental contaminants with known toxic and carcinogenic properties. Monitoring their levels in municipal and industrial wastewater is crucial for regulatory compliance and protection of ecosystems. Gas chromatography coupled with mass spectrometry (GC/MS) remains a gold-standard approach for PAH analysis, but performance depends heavily on column chemistry and instrument parameters.

Objectives and Study Overview

This application note evaluates the suitability of the TraceGOLD™ TG-5SilMS GC column for analyzing 16 EPA-listed PAHs in wastewater samples. The aim is to demonstrate compliance with US EPA Method 610 and assess extension of the method to EPA Method 8100.

Methodology

Sample preparation and analysis were performed as follows:

• Standard solution: 1 ng/µL PAH mix in dichloromethane/benzene.
• Injection: 1 µL splitless injection using TriPlus autosampler.
• Oven program: 60 °C hold (5 min), ramp at 8 °C/min to 300 °C, hold (10 min).
• Carrier gas: Helium at 1.5 mL/min (constant flow).
• MS acquisition: Electron impact ionization at 70 eV, segmented scan 45–450 amu.

Instrumental Setup

• Gas chromatograph: Thermo Scientific TRACE GC Ultra.
• Column: TraceGOLD TG-5SilMS, 30 m × 0.25 mm × 0.25 µm; 2 m guard column.
• Mass spectrometer: Thermo Scientific Ion Trap MS (ITD 230LT).
• Autosampler: Thermo Scientific TriPlus.
• Data system: Thermo Scientific Xcalibur software.

Key Results and Discussion

The TG-5SilMS column achieved baseline separation of all 16 target PAHs with minimal peak tailing. The low-polarity silarylene phase minimized analyte interaction with active sites, ensuring sharp peaks and consistent retention times. The resulting total ion chromatogram demonstrates clear resolution suitable for both EPA Methods 610 and 8100.

Practical Benefits and Applications

The optimized method offers:

• High selectivity and sensitivity for regulatory monitoring.
• Reproducible retention times supporting quantitation.
• Compatibility with routine wastewater testing in QA/QC laboratories.

Future Trends and Opportunities

Advancements may include coupling GC/MS with high-resolution mass spectrometers, miniaturized sampling techniques, automated sample preparation workflows, and adoption of greener solvents. Real-time or on-site PAH monitoring platforms could further expand environmental surveillance capabilities.

Conclusion

The TraceGOLD TG-5SilMS column, combined with a Thermo Scientific GC/MS system, meets EPA requirements for PAH analysis in wastewater. It delivers reliable separation, robust performance, and seamless integration into environmental testing laboratories.

References

1. US EPA. Method 610: Polynuclear Aromatic Hydrocarbons in Water, 40 CFR 136.1.
2. US EPA. Method 8100: Polynuclear Aromatic Hydrocarbons by Gas Chromatography.