Validation of USEPA Method 524.2 Using a Stratum PTC, AQUATek 100 Autosampler, and Perkin-Elmer Clarus 600 GC/MS

Importance of the Topic

Detection of low-level volatile organic compounds (VOCs) in water supplies is essential to protect public health and meet regulatory standards established by the US EPA. Method 524.2 provides a robust protocol for measuring purgeable organic compounds in drinking water, groundwater, and surface water.

Objectives and Study Overview

This study aimed to validate US EPA Method 524.2 by pairing a Teledyne Tekmar Stratum purge and trap concentrator with an AQUATek 100 autosampler and a Perkin-Elmer Clarus 600 GC/MS system. Key goals included establishing linear calibration for target VOCs and determining method detection limits (MDLs) under full automation of sample preparation.

Instrumentation Used

• Teledyne Tekmar Stratum purge and trap concentrator with proprietary trap 9
• AQUATek 100 autosampler featuring a 100-position sample tray and standard addition vessels
• Perkin-Elmer Clarus 600 gas chromatograph with Elite-624 capillary column (20 m × 0.18 mm × 1.0 µm)
• Perkin-Elmer Clarus 600T quadrupole mass spectrometer

Methodology and Instrumentation

Liquid samples (25 mL) were purged at 20 °C for 11 minutes with helium at 40 mL/min. VOCs were trapped, thermally desorbed at 245 °C–250 °C, and introduced onto the GC column. The oven program ramped from 35 °C (2 min) to 200 °C at 10 °C/min, then to 240 °C at 50 °C/min. The MS scanned 35–300 m/z in electron ionization mode. Calibration standards ranged from 0.2 ppb to 50 ppb, with internal and surrogate standards added to each sample. Seven replicates at 0.2 ppb were used to establish MDLs.

Main Results and Discussion

Calibration curves for all 64 compounds demonstrated linearity with relative standard deviations mostly below 10 %, averaging 7 %. Method detection limits were below 0.2 ppb for every target analyte. A representative total ion chromatogram at 10 ppb showed clear separation of VOC peaks, confirming system performance meets all EPA criteria.

Benefits and Practical Applications

• Full automation reduces manual sample handling and risk of error
• High throughput enabled by the 100-position tray
• Maintained sensitivity and precision for regulatory compliance
• Cost and time savings for routine water monitoring laboratories

Future Trends and Applications

• Implementation of advanced data analytics and machine learning for rapid interpretation of VOC profiles
• Development of portable purge and trap GC/MS systems for field analysis
• Extension to emerging contaminants and real-time monitoring applications

Conclusion

This validation confirms that coupling the Stratum PTC and AQUATek 100 with the Clarus 600 GC/MS satisfies all performance requirements of EPA Method 524.2. Automation enhances laboratory efficiency without compromising sensitivity, supporting reliable VOC analysis in drinking water quality programs.

Reference

• USEPA Method 524.2 Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry Revision 4.1 1995