US EPA Method 524.3 with the Teledyne Tekmar Atomx XYZ and Thermo Scientific™ TRACE™ 1310 GC and ISQ™ 7000 MS with an Advanced Electron Ionization (AEI) Source

Importance of the Topic

The analysis of volatile organic compounds (VOCs) in drinking water is critical for ensuring public health and regulatory compliance. US EPA Method 524.3 provides standardized procedures for detecting trace-level VOCs, supporting accurate monitoring of water quality and safeguarding against contamination. The combination of an advanced purge and trap system with robust GC-MS detection enhances sensitivity, throughput and reliability in routine environmental testing.

Objectives and Study Overview

This study evaluated the performance of the Teledyne Tekmar Atomx XYZ purge and trap system coupled with a Thermo Scientific TRACE 1310 GC and ISQ 7000 MS equipped with an Advanced Electron Ionization (AEI) source. Key objectives included establishing a linear calibration from 0.2 to 50 ppb, determining method detection limits (MDLs), assessing accuracy and precision at 0.5 ppb, and verifying midpoint performance at 20 ppb for 73 target VOCs following US EPA Method 524.3.

Methodology

Sample Preparation

• Calibration standards: Nine-point curve (0.2–50 ppb) prepared from Restek® 524.3 VOA Mega Mix™ and Gas Calibration Mix, r² ≥ 0.995.
• Internal standards: 1,4-Difluorobenzene, Chlorobenzene-d5, 1,4-Dichlorobenzene-d4 (25 ppb in sample).
• Surrogates: Methyl-tert-Butyl Ether-d3, 4-Bromofluorobenzene, 1,2-Dichlorobenzene-d4.
• MDL/accuracy/precision: Ten replicates at 0.5 ppb; midpoint check: ten replicates at 20 ppb.

Použitá instrumentace

• Teledyne Tekmar Atomx XYZ P&T: Efficient trap cooling, moisture control system, 84-position autosampler.
• Thermo Scientific TRACE 1310 GC: Rtx® VMS 20 m × 0.18 mm, 1 µm film, helium 0.8 mL/min, oven ramp 35 °C to 225 °C in 15 min.
• Thermo Scientific ISQ 7000 MS with AEI source: Transfer line 300 °C, source 280 °C, scan 35–260 amu, 0.15 s dwell.

Main Results and Discussion

• Calibration: Linear response for all compounds (r² ≥ 0.995) across 0.2–50 ppb.
• MDLs: Typically between 0.03 and 0.27 ppb, meeting EPA limits.
• Accuracy and Precision: Mean recoveries 83–118 % at 0.5 ppb, precision ≤ 20 % RSD.
• Midpoint performance: Recoveries 68–139 % at 20 ppb, within ±50 %–150 % criteria.
• Chromatographic Performance: Clear peak shapes, minimal water interference demonstrated in 20 ppb total ion chromatogram.
• Throughput: Up to three samples per hour; potential for further cycle reduction by optimizing GC oven program.

Practical Benefits and Applications

• High sensitivity and selectivity for trace VOC analysis in drinking water.
• Reduced cycle time and sample carry-over due to advanced trap cooling and moisture control.
• Scalable workflow for environmental and regulatory laboratories.
• Robust performance with minimal maintenance and prolonged column life span.

Future Trends and Potential Applications

• Further integration of automation and software-driven data processing to increase throughput.
• Adoption of high-resolution and tandem MS for improved compound identification.
• Extension to other matrices, such as soil, wastewater and air monitoring.
• Development of miniaturized P&T-GC-MS systems for field applications.
• Integration with online monitoring networks for real-time environmental surveillance.

Conclusion

The Atomx XYZ P&T and TRACE 1310 GC/ISQ 7000 MS with AEI source fulfill all performance criteria of US EPA Method 524.3 for VOC analysis in drinking water. The method offers excellent linearity, low detection limits, and reliable accuracy and precision with minimal water interference. Its high throughput and robustness make it a valuable tool for routine environmental monitoring and regulatory compliance.

Reference

1. Munch, J.W. Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry; US EPA Method 524.3, Revision 1.0, June 2009.