US EPA Method 524.2 using the Teledyne Tekmar Atomx XYZ and Thermo Scientific™ ISQ™ 7000 Mass Spectrometry (MS) System Coupled with a Thermo Scientific™ TRACE™ 1310 Gas Chromatograph (GC)

Significance of the Topic

The reliable detection of volatile organic compounds (VOCs) in drinking water at sub‐ppb levels is critical for public health and regulatory compliance. US EPA Method 524.2 is a gold standard for trace VOC analysis, but conventional purge and trap systems transfer excessive water vapor to the GC/MS, compromising sensitivity, resolution, and column life.

Aims and Overview of the Study

This study evaluates the performance of the Teledyne Tekmar Atomx XYZ purge and trap (P&T) system, featuring an innovative moisture control system (MCS), coupled to a Thermo Scientific TRACE 1310 gas chromatograph and ISQ 7000 mass spectrometer. Key objectives include establishing linear calibration curves (0.2–50 ppb), determining method detection limits (MDLs), and demonstrating effective water removal during sample desorption.

Methodology

A 25 ppm working standard was prepared from Restek Drinking Water VOA MegaMix™, Ketone Mix, and 502.2 Calibration Mix, covering 80 target VOCs. Calibration curves employed seven levels (0.2–50 ppb) with fluorobenzene as the internal standard and 4‐bromofluorobenzene plus 1,2‐dichlorobenzene‐d4 as surrogates. Method detection limits and precision were assessed using seven replicates at 0.5 ppb, and accuracy/precision at 5 ppb. Atomx XYZ operational parameters (trap temperatures, purge flows, desorb time 4 min) and GC‐MS conditions (TRACE 1310 column program, ISQ 7000 full‐scan 35–260 amu) were applied as per EPA Method 524.2.

Instrumentation Used

• Teledyne Tekmar Atomx XYZ P&T sample preparation system with moisture control system (MCS)
• Thermo Scientific TRACE 1310 gas chromatograph equipped with TG VMS 20 m × 0.18 mm column, helium carrier (1 mL/min)
• Thermo Scientific ISQ 7000 mass spectrometer, full‐scan mode (35–260 amu)
• 84‐position soil and water autosampler and precision‐machined valve manifold block

Main Results and Discussion

Calibration curves exhibited excellent linearity (%RSD of response factors within method limits). MDLs ranged from 0.043 to 0.263 ppb across compounds. Accuracy and precision at 5 ppb met EPA criteria (±20%), with typical recoveries between 92–120% and %RSD ≤ 20%. The Atomx XYZ MCS reduced water interference by up to 60%, yielding sharp, well‐resolved peaks in a 5 ppb total ion chromatogram and extending GC column lifespan.

Benefits and Practical Applications of the Method

The combined Atomx XYZ/TRACE 1310/ISQ 7000 platform enables rapid, high-throughput VOC analysis with a 14% shorter sample cycle time, robust moisture removal, consistent quantification at low ppb levels, and reduced instrument maintenance. This workflow is ideal for environmental laboratories performing routine QA/QC of drinking water.

Future Trends and Potential Applications

Advancements may include further optimization of GC temperature programs for reduced run times, expansion to emerging contaminant classes, integration of real-time data processing with machine learning, development of miniaturized P&T modules for field use, and coupling with online monitoring systems for continuous water quality surveillance.

Conclusion

The Teledyne Tekmar Atomx XYZ P&T system with moisture control, combined with Thermo Scientific TRACE 1310 GC and ISQ 7000 MS, successfully implements US EPA Method 524.2. It delivers low MDLs, high accuracy and precision, minimal water interference, and increased laboratory throughput, meeting stringent regulatory requirements for VOC analysis in drinking water.

References

1. U.S. EPA. 1992. Method 524.2: Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry, Revision 4.1.