Measurement of VOCs in Vehicle Interiors withNitrogen as the Carrier Gas

Importance of the Topic

Volatile organic compounds (VOCs) released from materials inside vehicle cabins can affect indoor air quality and occupant comfort. Monitoring these compounds is essential for automotive manufacturers to ensure compliance with health and safety regulations and to meet consumer expectations for odor and air purity. Implementing robust analytical methods supports quality control, material selection and environmental certification processes.

Objectives and Study Overview

This work demonstrates a thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) method using nitrogen as an alternative carrier gas. The primary goals were to optimize sampling and separation conditions for nine representative VOCs and to assess whether nitrogen can replace helium without compromising analytical performance.

Methodology and Instrumentation

• Instrumentation: Shimadzu GCMS-QP2020 NX coupled with TD-30R thermal desorption unit.
• Desorption parameters: Tube desorb at 280 °C for 10 min, flow 60 mL/min; trap cooled at –20 °C then desorbed at 280 °C for 10 min.
• GC conditions: SH-5MS column (30 m × 0.25 mm, 0.25 µm), split injection (ratio 50:1), carrier gas N₂ at linear velocity 40 cm/s.
• Oven program: 40 °C (1 min) ramp 10 °C/min to 100 °C, then 40 °C/min to 200 °C followed by 20 °C/min to 300 °C (hold 5 min).
• MS detection: Electron impact scan mode, m/z 45–600, event time 0.3 s; interface at 280 °C, source at 230 °C.
• Analytes: Benzene, toluene, ethylbenzene, isomers of xylene, styrene, 1,4-dichlorobenzene and tetradecane (each 1 µg).

Main Results and Discussion

Separation of all nine compounds was achieved within 11 minutes, with clear baseline resolution. Peak shapes and signal intensities were comparable to standard helium-based methods, demonstrating that nitrogen can provide sufficient chromatographic efficiency for routine VOC analysis. Signal stability and reproducibility met typical QA/QC criteria, confirming the method’s robustness.

Benefits and Practical Applications

• Cost efficiency: Use of nitrogen reduces carrier gas expenses and dependence on helium supply.
• Operational simplicity: Maintains standard TD–GC–MS workflows without hardware modifications.
• Environmental impact: Nitrogen is non-flammable and readily available, enhancing safety and sustainability.
• Quality control: Suitable for routine monitoring of cabin air quality and material off-gassing tests.

Future Trends and Potential Applications

Advancements in column technology and faster thermal desorption modules may further reduce analysis times. Integration of high-resolution mass spectrometry and machine learning algorithms could enhance compound identification and source attribution. Expansion to a broader range of indoor air pollutants and real-time monitoring solutions will support emerging regulatory requirements and smart vehicle interiors.

Conclusion

This study validates the use of nitrogen as a viable carrier gas for TD–GC–MS measurement of key VOCs in vehicle interiors. The method offers comparable performance to helium-based analyses while delivering cost and environmental benefits, supporting its adoption for automotive air-quality testing.

References

Application News 01-00366 (JP, ENG), Shimadzu Corporation, First Edition Sep. 2022, ERAS-1000-0405