TO-15 65 Component Mix on Rxi®-5Sil MS (30 m, 1.5 mL/min)

Importance of the Topic

Volatile organic compounds (VOCs) play a critical role in environmental monitoring, occupational health and safety, and industrial process control. High‐resolution analysis of complex VOC mixtures ensures accurate assessment of air quality and regulatory compliance. The TO‐15 65‐component mix on an Rxi®‐5Sil MS column demonstrates a robust workflow for simultaneous determination of a wide range of halogenated and non‐halogenated compounds at low parts-per-billion levels.

Study Objectives and Overview

The primary goal was to evaluate chromatographic separation and detection of 65 target analytes under standardized EPA TO‐15 conditions. Key aims included:

• Assessing retention behavior on a 30 m × 0.32 mm ID, 1.0 µm Rxi®‐5Sil MS column.
• Validating preconcentration and cryofocusing performance using Nutech traps and Tenax® sorbent.
• Demonstrating reliable quantitation via electron impact mass spectrometry on an HP 6890 GC coupled to a 5973 MSD.

Methodology and Instrumentation

Sample introduction employed direct 400 mL injection into a dual‐trap cryofocusing system (Glass beads at –155 °C and Tenax® at –160 °C). Preconcentration used a Nutech 8900DS with nitrogen diluent at 10 ppbv. GC conditions:

• Carrier gas: Helium at 1.5 mL/min constant flow.
• Oven program: 32 °C (1 min) to 150 °C at 9 °C/min, then 230 °C at 33 °C/min.
• Column: Rxi®‐5Sil MS, 30 m, 0.32 mm ID, 1.00 µm film thickness.
• Detector: Quadrupole MS in full‐scan EI mode (69.9 eV, 230 °C source).

Key Results and Discussion

All 65 compounds were baseline–resolved with retention times spanning 1.57 to 14.89 minutes. Early eluters included light gases like propylene and chloromethane (<2 min), while heavier aromatics such as naphthalene and hexachlorobutadiene appeared beyond 14 min. Coelution challenges for compounds sharing m/z 43 (e.g., MEK and hexane) were addressed by unique ion ratios. The optimized temperature ramp and dual‐trap focusing yielded sharp peaks with excellent signal–to–noise ratios.

Benefits and Practical Applications

• Comprehensive VOC profiling in ambient air, indoor environments and process emissions.
• Regulatory compliance testing according to EPA Method TO‐15.
• Reliable trace‐level quantitation for QA/QC in environmental laboratories.

Future Trends and Opportunities

Advances may include integration of high‐resolution time‐of‐flight MS for improved compound identification, automated multi‐column switching for broader analyte coverage, and miniaturized preconcentration devices to reduce sample volume. Coupling with real‐time screening techniques and data analytics will further enhance throughput and decision‐making.

Conclusion

This study highlights a validated GC‐MS approach capable of separating and quantifying a diverse set of 65 VOCs with high sensitivity and reproducibility. The combination of cryofocusing, optimized temperature programming and quadrupole detection provides a versatile platform for environmental and industrial air monitoring.

Reference

None provided in the source document.