US EPA Method 524.4 with the Tekmar Lumin P & T Concentrator and Agilent 7890B GC and 5977A MSD System

Importance of the Topic

Monitoring volatile organic compounds in drinking water is crucial for public health protection and regulatory compliance. Method 524.4 established by US EPA is a standard approach for detecting trace levels of these compounds. However GC MS analysis faces challenges due to water vapor contamination which can degrade column performance and require frequent maintenance.

Objectives and Overview of the Study

This work demonstrates the capability of a purge and trap concentrator with an integrated moisture control system to reduce water vapor transfer to the GC MS detector compared with traditional systems. Key goals include evaluation of calibration linearity detection limits and water management efficiency under Method 524.4 conditions.

Methodology

• Calibration standards spanning 0.2 to 50 ppb prepared in deionized water with internal and surrogate standards
• Sample analysis using dynamic purge and trap with adjustable dry purge and desorb parameters
• Determination of method detection limit accuracy and precision at 0.5 and 5 ppb levels

Used Instrumentation

• Tekmar Lumin purge and trap concentrator with moisture control system
• AQUATek 100 sample autosampler
• Agilent 7890B gas chromatograph with DB 624 UI column
• Agilent 5977A mass selective detector

Main Results and Discussion

• Moisture control system substantially reduced water load on GC MS during desorption
• Calibration curves exhibited excellent linearity with correlation coefficients near unity
• Method detection limits ranged from 0.05 to 0.19 ppb meeting regulatory requirements
• Accuracy and precision for seven replicate analyses at 0.5 ppb fell within method criteria

Benefits and Practical Applications

• Reduced instrument maintenance and column degradation due to water management
• Improved chromatography for early eluting compounds
• Cost savings from use of nitrogen purge gas
• Higher sample throughput enabled by faster trap cooling and shorter cycle times

Future Trends and Opportunities for Application

• Further refinement of moisture management for trace analysis in water and other matrices
• Integration with automated workflows and data processing tools
• Extension to analysis of emerging contaminants and complex sample types

Conclusion

Integration of a moisture control enabled purge and trap concentrator with standard GC MS instrumentation under US EPA Method 524.4 delivers reliable trace VOC analysis in drinking water with minimal water interference. The system meets all key performance metrics and supports high throughput environmental monitoring.

Reference

1 Munch JW Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography Mass Spectrometry US EPA Method 524.3 Revision 1.0 June 2009