Semivolatile Organics US EPA Method 8270 - Rxi®-5Sil MS

Importance of the Topic

Semivolatile organic compounds (SVOCs) encompass a broad range of environmentally significant pollutants including phenols, phthalates, nitroaromatics, and polycyclic aromatic hydrocarbons. Accurate and reproducible measurement of these analytes is essential for environmental monitoring, regulatory compliance, and risk assessment. US EPA Method 8270D provides a standardized framework for the analysis of SVOCs by gas chromatography–mass spectrometry (GC–MS).

Goals and Study Overview

This application note demonstrates the performance of the Restek Rxi®-5Sil MS GC column for the separation and detection of a representative SVOC mixture following EPA Method 8270D. A total of 93 compounds, spanning low–molecular-weight nitrosamines to high–molecular-weight polycyclic aromatics, were evaluated for chromatographic resolution, sensitivity, and reproducibility.

Methodology and Instrumentation

The SVOC standard mix (10 µg/mL of each analyte, 40 µg/mL internal standards) was injected at 1 µL (10 ng on column) using a pulsed splitless inlet (30 psi pulse for 0.3 min, 40 mL/min carrier purge at 0.25 min). Key GC–MS parameters included:

• Column: Rxi-5Sil MS, 30 m × 0.25 mm ID, 0.5 µm film
• Carrier gas: Helium, constant flow at 1.2 mL/min
• Oven program: 40 °C (1 min) to 280 °C at 25 °C/min, then to 320 °C at 5 °C/min (3.5 min hold)
• Inlet temperature: 250 °C with a drilled Uniliner®
• Mass spectrometer: Electron ionization, scan range 35–550 amu, transfer line at 280 °C

Instrumentation Used

• Gas chromatograph with pulsed splitless inlet and drilled Uniliner® sleeve
• Restek Rxi-5Sil MS capillary column (0.5 µm film thickness)
• Single quadrupole mass spectrometer operated in full-scan EI mode

Main Results and Discussion

The extracted ion chromatogram (EIC) demonstrated baseline resolution of all 93 target compounds, including critical pairs such as 2,4-dinitrophenol/2-nitrophenol and high-boiling PAHs. Retention times were reproducible with relative standard deviations below 0.2%. The silarylene phase and 0.5 µm film thickness contributed to sharp peak shapes and minimal bleed at high temperatures. Sensitivity at 10 ng on column provided clear detection of nitrosamines and halogenated phenols.

Benefits and Practical Applications

The optimized method supports routine analysis of SVOCs in environmental matrices (soil, water, air) and quality control of industrial products. Key advantages include:

• Comprehensive coverage of priority pollutants in a single run
• Robust performance across a wide volatility range
• High throughput with rapid temperature programming
• Enhanced column longevity using the Uniliner® and low-bleed phases

Future Trends and Opportunities

Emerging directions in SVOC analysis include two-dimensional GC for complex mixtures, hyphenation with high-resolution MS for increased specificity, and miniaturized/portable systems for field deployment. Advances in stationary phase chemistries may further improve selectivity for isomeric analytes and reduce analysis time.

Conclusion

The Restek Rxi-5Sil MS column, combined with pulsed splitless injection and optimized temperature programming, reliably separates and detects a broad suite of 93 semivolatile organic compounds in accordance with US EPA Method 8270D. The method offers high sensitivity, excellent reproducibility, and operational robustness for environmental and industrial applications.

References

• US EPA Method 8270D: Semivolatile Organic Compounds by GC–MS
• Restek Corporation. Rxi-5Sil MS GC Column Product Information