TO-15 65 Component Mix on Rtx®-VMS (30 m)

Importance of the Topic

Volatile organic compounds (VOCs) are critical indicators in environmental and industrial quality assessments. Comprehensive analysis of a broad VOC panel supports regulatory compliance, contamination tracking, and indoor/outdoor air quality monitoring. The TO-15 method with a 65-component target mix offers a standardized approach for sensitive and reliable VOC determination.

Objectives and Study Overview

This application demonstrates the separation and quantification of 65 VOCs using a Restek Rtx®-VMS column on a GC/MS system. The primary goals are to achieve baseline resolution of diverse compounds, establish robust retention times, and ensure accurate quantitation at low parts-per-billion levels.

Methodology and Instrumentation

• Column: Rtx®-VMS, 30 m × 0.32 mm ID, 1.8 µm film thickness.
• Carrier Gas: Helium at constant flow of 2.0 mL/min (linear velocity 51 cm/s at 32 °C).
• Oven Program: 32 °C hold 1 min; ramp to 150 °C at 11 °C/min; ramp to 230 °C at 33 °C/min.
• Sample Introduction: Direct 200 cc injection of 10 ppbv TO-15 mix in nitrogen, preconcentrated on a Tenax® trap with cryofocusing.
• Preconcentrator: Nutech 8900DS, Trap 1 (glass beads) cooled to –155 °C, Trap 2 (Tenax®) cooled to –35 °C, thermal desorption at 190 °C for 30 s.
• Detection: HP 6890 GC coupled to 5973 MSD, electron ionization at 69.9 eV, scan range 35–250 amu at 3.32 scans/sec.

Main Results and Discussion

All 65 analytes eluted within a 13.5-minute run, with retention times spanning 1.42 min for propylene to 13.42 min for naphthalene. The Rtx-VMS column provided sharp, symmetrical peaks and resolved critical isomer pairs such as o-, m-, and p-xylenes, as well as chlorobenzene isomers. Chromatographic resolution met TO-15 specifications, with minimal coelution observed.

Benefits and Practical Applications

• Rapid, high-throughput VOC screening for environmental laboratories.
• Compliance with EPA TO-15 protocols for air quality and contamination studies.
• Sensitive detection at low ppbv levels ensuring traceability.
• Applicability to indoor air, soil gas, water headspace, and workplace monitoring.

Future Trends and Opportunities

Advances may include ultrafast temperature programming, improved cryogenic focusing for trace analytes, and automated multi-column switching to broaden analyte ranges. Integration with real-time data analytics and machine learning could enhance identification confidence and method throughput.

Conclusion

The described method effectively separates and quantifies a comprehensive 65-component VOC mixture using an Rtx-VMS column and GC/MS. It delivers robust, sensitive, and reproducible results, supporting regulatory and research applications in environmental and industrial monitoring.