US EPA Method 8260 with the Tekmar Lumin and the Agilent 7890B GC / 5977A MS

Importance of the Topic

The analysis of volatile organic compounds in water and wet soils is essential for environmental monitoring and regulatory compliance. US EPA Method 8260 is widely adopted in environmental laboratories, but traditional purge and trap workflows often introduce excess water vapor into GC/MS systems, compromising chromatographic performance and throughput.

Objectives and Study Overview

This application note evaluates the performance of the Teledyne Tekmar Lumin Purge and Trap concentrator with its integrated Moisture Control System and the Agilent 7890B GC/5977A MS. The goal is to assess water vapor reduction, method detection limits, calibration linearity, precision and accuracy under US EPA Methods 8260 and 5030 workflows without employing dry purge.

Methodology and Instrumentation

Sample Preparation

• Calibration standards prepared from Restek VOC mixes spanning sub-ppb to high-ppb ranges, including ketones and t-butanol at elevated levels
• Internal standards: 1,4-difluorobenzene, chlorobenzene-d5, 1,4-dichlorobenzene-d4
• Surrogates: dibromofluoromethane, 1,2-dichloroethane-d4, toluene-d8, pentafluorobenzene, fluorobenzene, bromofluorobenzene

Instrument Conditions

• Purge and Trap: Lumin Purge and Trap concentrator with Moisture Control System and AQUATek 100 sampler
• GC/MS: Agilent 7890B GC with DB-624 UI column and 5977A MS in full scan mode (35–270 m/z)
• No dry purge step; optimized bake and desorb temperatures with efficient trap cooling to shorten cycle times

Main Results and Discussion

Calibration, Detection Limits and Precision

• Excellent linearity for 90+ VOCs across ppb ranges; relative standard deviation of response factors typically below 10%
• Method detection limits ranging from 0.04 ppb to 1.40 ppb for compounds and surrogates
• Accuracy within 90–113% at 0.5 ppb (or higher for specialized compounds) and precision (%RSD) below 12% for most analytes

Chromatographic Performance

• 0.5 ppb standard showed clear, interference-free peaks for early eluting compounds with no dry purge
• 30 ppb standard TIC displayed consistent peak shapes and resolution across all VOCs
• Internal and surrogate standard peak areas over 9 hours (30 injections) exhibited minimal drift (RSD below 5%)

Benefits and Practical Applications

• Significant reduction of water vapor transfer to GC/MS without a dry purge step improves early peak shape and sensitivity
• Shortened sample cycle times via integrated moisture control and efficient trap cooling enhances laboratory throughput
• Compatibility with established EPA workflows ensures method compliance while reducing maintenance burdens

Future Trends and Applications

Continued innovation in moisture management and concentrator design can further reduce cycle times and instrument downtime. Integration of advanced materials for trapping and faster temperature programming in GC ovens promises even higher sample throughput. Potential extends to automated field deployable systems for on-site VOC monitoring.

Conclusion

The Tekmar Lumin Purge and Trap concentrator coupled with the Agilent 7890B/5977A GC/MS system delivers robust performance for EPA Method 8260 analyses without requiring dry purge. Superior water vapor control, excellent sensitivity, precision and accuracy, and shortened cycle times support high-throughput environmental testing.

Used Instrumentation

• Teledyne Tekmar Lumin Purge and Trap Concentrator with Moisture Control System
• AQUATek 100 Sampler
• Agilent 7890B Gas Chromatograph with DB-624 UI column
• Agilent 5977A Mass Spectrometer

References

1. US EPA SW-846 Method 8260B Revision 2, December 1996
2. US EPA SW-846 Method 8260C Revision 3, August 2006
3. US EPA SW-846 Method 5030B Revision 2, December 1996
4. US EPA SW-846 Method 5030C Revision 3, May 2003