Volatiles by EPA Method 8260 on Rxi®-624Sil MS (30 m, 0.25 mm ID, 1.40 μm)

Significance of the topic

Volatile organic compounds (VOCs) are widespread environmental pollutants with major implications for public health and regulatory compliance. EPA Method 8260 is a reference procedure for detecting and quantifying trace-level VOCs in water, soil and air matrices. High resolution, low-bleed capillary columns and sensitive mass spectrometric detection are critical to reliably separate complex mixtures and meet stringent quality control requirements.

Objectives and Overview of the Study

This application note evaluates the performance of the Rxi®-624Sil MS column (30 m × 0.25 mm ID, 1.40 µm) for EPA Method 8260 analyses. Key goals are to demonstrate resolution of critical compound pairs, maintain baseline stability at low detection limits, and verify compatibility with purge-and-trap sampling. The study encompasses surrogate mixes, internal standards and calibration blends representative of regulatory protocols.

Methodology and Instrumentation

An OI Analytical 4660 purge-and-trap system was used to introduce aqueous samples spiked at 25 ppb into an Agilent 7890A GC coupled to a 5975C quadrupole MSD operated in full-scan mode (36–260 amu). Trap and desorption parameters were optimized (purge 11 min at 20 °C; desorb at 190 °C; bake 5 min at 210 °C). The GC oven program started at 35 °C (hold 5 min), ramped to 60 °C at 11 °C/min then to 220 °C at 20 °C/min (hold 2 min). Helium carrier gas flowed at 1.0 mL/min. Ion source and transfer line temperatures were maintained at 230 °C, with electron energy set to 70 eV. A BFB tune ensured robust mass calibration.

Main Results and Discussion

Chromatograms displayed clear baseline separation of over 100 target VOCs spanning light gases to semi-volatiles. Critical pairs such as cis-/trans-1,2-dichloroethene, 1,3-butadiene isomers and various chlorinated benzenes resolved with resolution factors above regulatory thresholds. The low-bleed characteristic of the 624Sil phase minimized background noise, enabling reliable quantification at sub-ppb levels. Retention time repeatability was better than 0.01 min, supporting high-throughput batch analyses.

Benefits and Practical Applications

• Enhanced separation of complex VOC mixtures improves accuracy in environmental and industrial QA/QC.
• Low bleed and inertness extend column lifetime and reduce maintenance.
• Compatibility with standard purge-and-trap systems streamlines method implementation.
• Reproducible retention times facilitate automated data processing and compliance reporting.

Future Trends and Potential Applications

Advances in stationary phase chemistries and ultrahigh-pressure GC promise further gains in speed and resolution. Coupling with tandem MS or high-resolution accurate mass spectrometers will enhance compound identification and trace-level quantification in emerging contaminants. Integration of automated data validation algorithms will accelerate regulatory workflows.

Conclusion

The Rxi-624Sil MS column paired with EPA Method 8260 purge-and-trap and mass spectrometric detection delivers a robust, sensitive platform for VOC analysis. Its superior resolution, low bleed and inertness meet the demands of environmental monitoring and industrial quality control, enabling confident detection of regulated compounds at trace levels.

Reference

• Restek Corporation. Application Note GC_EV1169: Volatiles by EPA Method 8260 on Rxi®-624Sil MS.