US EPA Method 524.2 with the Teledyne Tekmar Atomx XYZ and Thermo Scientific™ TRACE™ 1310 GC and ISQ™ 7000 MS System with an Advanced Electron Ionization (AEI) Source

Importance of the Topic

This application note addresses the determination of trace levels of volatile organic compounds (VOCs) in drinking water, a critical task for environmental monitoring and regulatory compliance. The reliable detection of VOCs at sub-ppb levels safeguards public health and informs water treatment strategies.

Objectives and Study Overview

The primary goal was to implement US EPA Method 524.2 using the Teledyne Tekmar Atomx XYZ purge-and-trap system coupled to a Thermo Scientific TRACE 1310 GC and ISQ 7000 MS with an advanced electron ionization source. Specific aims included:

• Generating linear calibration curves from 0.2 to 50 ppb for 82 target VOCs
• Determining method detection limits (MDLs), precision and accuracy at 0.5 ppb levels
• Evaluating moisture control to minimize water vapor interference in GC/MS analysis

Methodology and Instrumentation

Sample preparation involved spiking 5 mL water aliquots with methanolic standards and internal/surrogate standards to achieve 25 ppb. Ten replicate 0.5 ppb standards were used for MDL, precision and accuracy testing. The Atomx XYZ system operated under US EPA 524.2-based conditions, featuring rapid trap cooling, moisture control reducing water vapor by up to 60 %, and an 84-position autosampler to increase throughput by 14 %. GC separation used an Rtx® VMS column (20 m × 0.18 mm, 1 µm) with a temperature program from 35 °C to 225 °C over 15 min. MS detection was performed in scan mode from 35 to 260 amu with solvent delay and 0.15 s dwell time.

Results and Discussion

Calibration curves for all compounds exhibited relative standard deviations (RSDs) well below method limits (<20 %). MDLs ranged from 0.03 to 0.24 ppb, meeting or exceeding regulatory requirements. Accuracy values for ten replicates at 0.5 ppb fell within ±20 %, and precision (RSD) was ≤ 12.8 % for all analytes. The moisture control system effectively minimized water vapor transfer to GC/MS, evidenced by clean baselines and minimal peak interference in the 50 ppb total ion chromatogram.

Benefits and Practical Applications

This optimized workflow offers:

• High sensitivity for trace VOCs in water
• Improved instrument uptime and column longevity via moisture reduction
• Enhanced laboratory throughput through faster cycle times and autosampling
• Robust performance across a broad range of VOC chemistries

Future Trends and Potential Applications

Emerging opportunities include:

• Further cycle time reductions via tailored GC temperature programming
• Integration with automated data processing and cloud-based analytics
• Expansion to emerging contaminants and non-target screening
• Adaptation to field-deployable systems for on-site water quality assessment

Conclusion

The combination of the Atomx XYZ purge-and-trap system with TRACE 1310 GC/ISQ 7000 MS and AEI source provides a reliable, high-throughput solution for trace VOC analysis in drinking water under US EPA Method 524.2. The method delivers excellent linearity, low MDLs, and strong precision and accuracy, while advanced moisture control extends instrument life and enhances data quality.

Used Instrumentation

• Teledyne Tekmar Atomx XYZ purge-and-trap concentrator with moisture control
• Thermo Scientific TRACE 1310 gas chromatograph
• Thermo Scientific ISQ 7000 mass spectrometer with Advanced Electron Ionization (AEI) source
• Rtx® VMS capillary GC column, 20 m × 0.18 mm, 1 µm film

References

1. Munch JW. US EPA Method 524.2 – Measurement of Purgeable Organic Compounds in Water by Capillary Column GC/MS, Revision 4.1; 1995.