Volatile Organics US EPA Method 8260B - Rtx®-VMS

Importance of the Topic

The reliable measurement of trace volatile organic compounds (VOCs) in water is essential for environmental monitoring, public health protection, and regulatory compliance. EPA Method 8260B provides a standardized approach for the quantification of a broad range of VOCs at low nanogram-per-liter levels, ensuring data comparability across laboratories and jurisdictions.

Objectives and Study Overview

This application note evaluates the performance of a 20 m × 0.18 mm ID, 1.00 µm Rtx-VMS capillary column for the rapid separation and detection of 97 target VOCs in aqueous samples. The primary goals are to demonstrate chromatographic resolution, sensitivity, and robustness when combined with a dual purge-and-trap concentrator and mass spectrometric detection.

Methodology

Aqueous standards containing 10 ppb of most analytes (with higher spiking levels for certain alcohols, ketones, and internal standards) were processed using a Tekmar LSC-3100 purge-and-trap system. Samples underwent an 11-minute purge at 40 mL/min, followed by a 1-minute dry purge. Thermal desorption occurred at 250 °C for 2 minutes, with trap bake at 260 °C for 8 minutes. Chromatographic separation was achieved on the Rtx-VMS column under the following oven program: 50 °C hold for 4 minutes, ramp to 100 °C at 18 °C/min, then to 230 °C at 40 °C/min (3-minute final hold). Helium was used as carrier gas at ~1.0 mL/min constant flow. Mass detection (Agilent 5973 MSD) scanned 35–300 amu.

Used Instrumentation

• Tekmar LSC-3100 Purge and Trap concentrator with Vocarb 3000 trap (type K).
• Agilent 6890 gas chromatograph equipped with 20 m, 0.18 mm ID, 1.00 µm Rtx-VMS column (cat. # 49914).
• Agilent 5973 mass selective detector (scan mode, 35–300 amu).
• 0.53 mm ID Silcosteel® transfer line, 1 mm ID inlet liner, 1:40 split injection.

Key Results and Discussion

The Rtx-VMS column achieved baseline separation of 97 volatile compounds—including halogenated methanes, chlorinated ethanes, aromatic hydrocarbons, ketones, alcohols, and ethers—within a 10-minute run time. Retention times spanned from 1.03 minutes (dichlorodifluoromethane) to under 10 minutes (higher-boiling aromatics). The method provided sharp, symmetric peaks and reproducible quantitation at or below the 10 ppb reporting limit. Internal standards and surrogate recoveries met EPA performance criteria, demonstrating reliable accuracy and precision across the analyte panel.

Benefits and Practical Applications

• Rapid throughput: complete GC run in under 12 minutes improves laboratory efficiency.
• Comprehensive scope: 97 compounds cover common environmental VOCs and process-related contaminants.
• Robust sensitivity: detection limits in the low-µg/L to ng/L range support regulatory and research needs.
• High resolution: excellent peak shape and separation reduce interferences and simplify data analysis.

Future Trends and Potential Applications

Ongoing developments in column stationary phases and mass spectrometer sensitivity will further reduce analysis time and detection limits. Emerging applications include in-field mobile purge-trap GC-MS systems, automated high-throughput screening for wastewater monitoring, and integration with data-driven platforms for real-time environmental risk assessment.

Conclusion

The combination of EPA Method 8260B, the Rtx-VMS column, and a dual purge-and-trap GC-MS setup offers a fast, reliable, and sensitive solution for multi-component VOC analysis in water. The optimized method meets stringent performance requirements, facilitating regulatory compliance and high-quality environmental data.

References

A.L. Hilling and G. Smith, Environmental Testing & Analysis, 10(3):15–19, 2001.