TO-15 65 Component Mix on Rtx®-VMS (30 m, 2.0 mL/min)

Importance of TO-15 Analysis

TO-15 is a fundamental EPA method for quantifying 65 volatile organic compounds in air matrices. Its robust sensitivity and broad compound coverage make it indispensable for environmental monitoring, indoor air quality assessment, and regulatory compliance.

Objectives and Overview

This application note illustrates the chromatographic separation and detection of a 65-component TO-15 standard on an Rtx®-VMS column coupled to a quadrupole GC/MS system. The goal is to showcase retention behavior, resolution performance, and method parameters for rapid, reliable VOC analysis.

Methodology and Instrumentation

The analysis employed a 30 m × 0.25 mm ID, 1.40 µm Rtx®-VMS column with helium at 2.0 mL/min. A 400 mL injection of a 10 ppbv TO-15 mixture was preconcentrated on a Tenax® trap (Nutech 8900DS), cooled to –160 °C. GC oven programming began at 32 °C (1 min), ramped at 11 °C/min to 150 °C, then at 33 °C/min to 230 °C. The transfer line was held at 230 °C. MS detection used EI at 69.9 eV, scanning 35–250 amu at 3.32 scans/sec.

• Column: Rtx®-VMS, 30 m × 0.25 mm ID, 1.40 µm
• Preconcentrator: Nutech 8900DS with Tenax® trap
• GC/MS: Agilent HP6890 GC & 5973 MSD, quadrupole analyzer
• Carrier Gas: He, constant flow 2.0 mL/min
• Oven Program: 32 °C→150 °C (11 °C/min)→230 °C (33 °C/min)

Key Results and Discussion

The chromatogram resolved 71 peaks in under 14 minutes, covering aliphatic, halogenated, and aromatic VOCs. Early eluters such as propylene and Freon® components appeared between 1.5–2.8 min. Mid-range solvents and chlorinated species eluted from 3.0–6.0 min, while aromatic isomers and heavier halogenated compounds appeared from 6.0–13.4 min. Critical isomer separations—xylenes, dichlorobenzenes, trimethylbenzenes—achieved baseline resolution. The retention time reproducibility was within ±0.05 min across replicate runs.

Benefits and Practical Applications

This method offers rapid throughput, high sensitivity, and excellent isomer discrimination. It is well suited for ambient air monitoring, leak detection in industrial settings, indoor air quality surveys, and compliance testing under regulatory frameworks (e.g., EPA TO-15, ISO standards). Preconcentration enhances detection limits in the low-ppbv range.

Future Trends and Opportunities

Advancements in column technology may enable even faster ramp rates and shorter analysis times. High-resolution MS and ion mobility spectrometry coupling can improve compound identification in complex matrices. Field-deployable preconcentrators and real-time monitoring platforms will facilitate on-site VOC analysis. Machine-learning–driven deconvolution algorithms promise enhanced data processing for coeluting species.

Conclusion

The TO-15 methodology on an Rtx®-VMS column coupled with GC/MS delivers comprehensive separation of 65 key VOCs within 14 minutes, providing a robust, high-throughput solution for environmental and industrial air analysis.

References

• Restek Corporation. TO-15 65 Component Mix on Rtx®-VMS (30 m, 2.0 mL/min). Application Note.