Wisconsin Gasoline Range Organics (GRO) with the Atomx XYZ and Agilent 7890B GC/5977B MS

Significance of the Topic

Volatile organic compounds in water and soil pose significant environmental and health risks. Accurate quantification of gasoline-range organics is essential for regulatory compliance, site assessment and remediation monitoring.

Objectives and Study Overview

This study applies the modified Wisconsin Gasoline Range Organics (GRO) method to assess the performance of the Teledyne Tekmar Atomx XYZ purge and trap system coupled with an Agilent 7890B GC and 5977B MS. Key goals include establishing calibration linearity, determining method detection limits and verifying accuracy and precision for water, low-level and high-level soil samples.

Methodology and Instrumentation

Instrumentation:

• Purging and trapping with Teledyne Tekmar Atomx XYZ featuring enhanced trap cooling, moisture control system and 84-position autosampler.
• Agilent 7890B GC with Rtx® VMS column (20 m × 0.18 mm, 1 µm film) and 5977B MS, scanning 35–260 m/z.

Calibration and sample preparation:

• Nine-compound PVOC/GRO mix used to prepare water calibration (0.5–200 ppb), soil calibration (1–200 ppb) and methanol extraction curve (5–200 ppb).
• Internal standards (pentafluorobenzene, 1,4-difluorobenzene, chlorobenzene-d5, 1,4-dichlorobenzene-d4) and surrogates spiked at 25 ppb.
• MDL and mid-point verification samples prepared at 0.5 ppb (water), 2 ppb (soil) and 20 ppb levels.

Main Results and Discussion

Calibration curves demonstrated excellent linearity across all analytes. Method detection limits were below 0.15 ppb for water and 0.40 ppb for soil, with minimal water interference. Mid-point verification at 20 ppb showed relative standard deviations below 4% and average recoveries of 109% in water and 95% in soil. High-level soil methanol extraction achieved recoveries above 88% with RSDs under 11% for most compounds.

Benefits and Practical Applications

This configuration offers robust, high-throughput VOC analysis with shortened cycle times (14% improvement), enhanced moisture removal and extended column life. The automated workflow supports environmental laboratories in routine monitoring, site investigations and regulatory reporting.

Future Trends and Applications

Emerging opportunities include integration of rapid GC temperature programs to further boost throughput, implementation of machine-learning for data quality control, miniaturized purge and trap platforms and expansion to a broader suite of environmental contaminants.

Conclusion

The Atomx XYZ with Agilent GC/MS reliably fulfills Wisconsin GRO method requirements, delivering sensitive, precise and accurate VOC analysis in water and soil matrices while enhancing laboratory productivity.

References

Wisconsin Department of Natural Resources, Modified GRO Method for Determining Gasoline Range Organics, September 1995.