USEPA Method 524.4 Using the Teledyne Tekmar Atomx and Thermo Scientific™ GC/MS System with New Helium Saver Module

Significance of the Topic

Helium scarcity and rising cost have driven the update of drinking water analysis methods to allow nitrogen purge gas while maintaining analytical performance.

Objectives and Study Overview

• Demonstrate the use of nitrogen as purge gas in a Purge and Trap system
• Integrate Teledyne Tekmar Atomx with Thermo Scientific TRACE 1310 GC and ISQ LT MS using a Helium Saver Module
• Evaluate calibration, detection limits, precision, accuracy and regulatory compliance under USEPA Method 524.4

Methodology and Instrumentation

• Atomx Automated VOC Sample Prep System configured with nitrogen purge and optional chiller tray to maintain sample temperature below 10 °C
• Thermo Scientific TRACE 1310 GC and ISQ LT MS equipped with Instant Connect Helium Saver Module to minimize helium consumption
• TraceFinder EFS software for instrument control, data acquisition and processing with tuning on 4-bromofluorobenzene
• Purge and trap parameters optimized on Trap 9, with calibration standards prepared in 40 mL VOA vials, internal standards and preservation reagent
• Calibration curve spanning 0.2 to 100 ppb, MRL samples at 0.5 ppb and precision/accuracy samples at 20 ppb

Main Results and Discussion

• Most VOCs detected down to 0.2 ppb with clear peaks; four compounds only at 0.5 ppb and t-butyl alcohol at 1 ppb
• Calibration criteria met: ≤50% error at or below MRL and ≤30% above MRL for all compounds
• Precision (≤20% RSD) and accuracy (±20% recovery) confirmed at midpoint concentration with seven replicates
• LPIR ≥50% and UPIR ≤150% achieved for 75 of 76 VOCs at 0.5 ppb, demonstrating regulatory compliance

Benefits and Practical Applications

• Substantial reduction in helium usage and associated costs through use of Helium Saver Module
• Full compliance with USEPA Method 524.4 requirements for drinking water VOC analysis
• Automated sample handling and temperature control enhance laboratory throughput and reproducibility

Future Trends and Potential Applications

• Wider implementation of nitrogen purge methods in environmental monitoring laboratories
• Advances in carrier gas alternatives and trap technologies for further cost reduction
• Integration of real-time monitoring and data analytics for enhanced quality control
• Development of turnkey solutions combining automation and sustainable gas use

Conclusion

Nitrogen purge combined with the Instant Connect Helium Saver Module on a GC/MS platform provides a reliable, cost effective and compliant workflow for the analysis of purgeable VOCs in drinking water under USEPA Method 524.4.

References

• USEPA Method 524.4 Measurement of Purgeable Organic Compounds in Water by Gas Chromatography/Mass Spectrometry using Nitrogen Purge Gas May 2013