Aromatic hydrocarbons - Air-toxics analysis in chemical plant

Importance of the Topic

Rapid and accurate monitoring of volatile aromatic hydrocarbons and 1,3-butadiene in chemical plant atmospheres is critical for ensuring worker safety, regulatory compliance, and environmental protection. Traditional methods often require lengthy analysis times, delaying decision-making and response to potential air-toxic exposures.

Study Objectives and Overview

This application note presents a fast, selective gas chromatography–mass spectrometry method for simultaneous determination of a range of aromatic hydrocarbons and 1,3-butadiene collected from plant air using carbon-disc badges. The primary goal is to reduce analysis time while maintaining sensitivity and resolution.

Methodology and Instrumentation Used

A wide-bore GC system equipped with an Agilent Lowox 0.53 mm × 10 m fused-silica PLOT column (part no. CP8587) was employed. The temperature program ramped from 60 °C to 250 °C at 20 °C/min. Helium carrier gas was maintained at 20 kPa (0.2 bar) in constant pressure mode. A split injector (1:20) at 150 °C introduced samples prepared in carbon disulfide at 1 µg/mL. Detection was performed using mass spectrometry to achieve high selectivity. Airborne compounds were preconcentrated on 3M carbon-disc badges, achieving a detection limit of 0.15 ppm.

Main Results and Discussion

The optimized method achieved baseline separation of eight target analytes—including 1,3-butadiene, benzene, toluene, dicyclopentadiene, xylenes, and styrene—within an 11-minute runtime, a reduction from the typical 25–30 minutes. The MS detector also revealed trace artifacts such as limonene, acetone, and alcohols. Reproducibility and sensitivity met industry requirements for routine air-toxic surveillance.

Benefits and Practical Applications

• Run time reduced by over 50 %, increasing sample throughput.
• High selectivity for structurally similar aromatics and 1,3-butadiene.
• Low detection limit (0.15 ppm) suitable for workplace monitoring.
• Simple sampling using 3M carbon-disc badges facilitates on-site collection.
• Method can be integrated into QA/QC protocols for chemical and petrochemical facilities.

Future Trends and Potential Applications

Advances in column materials and micro-GC technologies promise even faster separations. Integration with time-of-flight MS or alternative detectors could enhance mass accuracy and dynamic range. Online, real-time monitoring systems and wireless sensor networks may leverage this approach for continuous air-toxic surveillance. Machine learning algorithms applied to spectral data are likely to further improve compound identification and quantification.

Conclusion

The fast GC–MS method detailed here offers a robust, efficient solution for monitoring aromatic hydrocarbons and 1,3-butadiene in chemical plant environments. The significant reduction in analysis time, coupled with high sensitivity and selectivity, supports improved safety practices and regulatory compliance.

References

• Agilent Technologies, Inc. (2011). Application Note A01652: Aromatic hydrocarbons Air-toxics analysis in chemical plant. First published prior to May 11, 2010; printed October 31, 2011.