BTEX Analysis with the Agilent 990 Micro GC System

Importance of the Topic

BTEX (benzene, toluene, ethylbenzene, and xylenes) are volatile organic compounds commonly used as markers of environmental contamination due to their toxicity and prevalence in industrial emissions and fuel vapors. Rapid and reliable detection of BTEX in air is essential for environmental monitoring, site assessment, and emergency response.

Objectives and Study Overview

The primary goal of this application study was to evaluate the performance of the Agilent 990 Micro GC system for fast, high-resolution analysis of BTEX in air. Key aims included:

• Assessing chromatographic resolution of xylene isomers on a wax phase column
• Determining repeatability of retention times and peak areas
• Establishing method detection limits under field-relevant conditions
• Verifying total analysis time for on-site decision making

Methodology and Instrumentation Used

An Agilent 990 Micro GC equipped with a 10 m Agilent J&W CP-Wax 52 CB straight channel was used. Instrument parameters were set as follows:

• Injector temperature: 110 °C
• Column pressure: 220 kPa
• Column temperature: 50 °C
• Carrier gas: helium
• Injection time: 80 ms (extendable to 150–200 ms for lower detection limits)
• Total run time: ~140 s

Main Results and Discussion

Chromatographic separation achieved clear resolution of all BTEX components, including baseline separation of p-, m- and o-xylene isomers. System performance was evaluated over 20 consecutive runs of a 50 ppm BTEX standard:

• Retention time repeatability (RSD): <0.01 %
• Peak area repeatability (RSD): 0.86–2.51 %

Detection limits were determined by diluting a 50 ppm standard to 6 ppm and computing MDLs at S/N = 2:

• Benzene: 0.50 ppm
• Toluene: 0.59 ppm
• Ethylbenzene: 0.83 ppm
• p-Xylene: 0.83 ppm
• m-Xylene: 1.00 ppm
• o-Xylene: 1.25 ppm

Moisture interference was observed adjacent to the toluene peak but did not compromise quantitation of BTEX components.

Benefits and Practical Use of the Method

The Agilent 990 Micro GC offers key advantages for field analysis:

• Portability and low power consumption for remote or emergency deployment
• Rapid runtime (<150 seconds) for accelerated decision making
• Laboratory-grade repeatability and resolution on a compact system
• Flexibility to adjust injection time and sensitivity based on sample requirements

Future Trends and Potential Applications

Anticipated developments and applications include:

• Integration with wireless data transfer and cloud-based reporting
• Hybrid column approaches or coupling with mass spectrometry for enhanced selectivity
• Expanded multi-analyte screening in industrial hygiene and indoor air quality
• Automated sample introduction and longer injection strategies to lower MDLs further

Conclusion

This study demonstrates that the Agilent 990 Micro GC, equipped with a polar wax column, provides fast, reliable, and high-resolution analysis of BTEX in air. Excellent repeatability and detection limits make it well suited for environmental monitoring and on-site emergency response scenarios.

Reference

1. Vattaire P, van Loon R. Analysis of BTEX in Air Using the Agilent 490 Micro GC. Agilent Technologies Application Note 5990-9527EN, 2011.