MEE Method HJ639 Using the Teledyne Tekmar Atomx XYZ P&T and Agilent GC/MSD to Determine Volatile Organic Compound Concentration in Water

Significance of the Topic

Monitoring trace levels of volatile organic compounds (VOCs) in water is essential to ensure compliance with environmental regulations, protect public health, and prevent ecological damage. Reliable quantification methods enable laboratories to detect contaminants at parts-per-billion levels, supporting risk assessment and remediation efforts.

Objectives and Study Overview

This study evaluates the performance of the Ministry of Ecology and Environment (MEE) Method HJ639 for VOC analysis in water using the Teledyne Tekmar Atomx XYZ purge and trap system coupled to an Agilent 7890B GC and 5977B MSD. The main aims were to establish linear calibration, determine method detection limits (MDLs), and verify precision and accuracy through midpoint checks.

Methodology and Instrumentation

A working standard containing 66 VOCs at 50 ppm in methanol was prepared, with internal standards (fluorobenzene, chlorobenzene-d5, 1,4-dichlorobenzene-d4) and surrogates (dibromofluoromethane, toluene-d8, 4-bromofluorobenzene) spiked to achieve target concentrations. Sample volumes of 5 mL were purged for 11 minutes at 40 mL/min, then desorbed at elevated temperature into the GC system. The GC program employed a 20 m × 0.18 mm DB-VRX column with a temperature gradient from 35 °C to 225 °C over 14.8 minutes. MS detection scanned 35–270 amu with a 0.15 s dwell time.

Used Instrumentation

• Teledyne Tekmar Atomx XYZ Purge & Trap System
• Agilent 7890B Gas Chromatograph
• Agilent 5977B Single Quadrupole Mass Spectrometer Detector

Main Results and Discussion

Calibration curves for all target VOCs showed excellent linearity (R² ≥ 0.99) with relative response factors exhibiting ≤ 20 % RSD. MDLs were below 0.25 ppb across the compound list. A 20 ppb midpoint check yielded average precision of 5 % RSD and recovery of 104 %, indicating accurate quantification. Total ion chromatograms of a 10 ppb standard demonstrated sharp peak resolution and minimal water interference.

Benefits and Practical Applications

• High sensitivity and low detection limits support compliance monitoring.
• Enhanced moisture control extends GC column life and reduces interference.
• Automated 84-position autosampler increases sample throughput over a 12-hour period.
• Robust valve manifold design minimizes leaks and downtime.

Future Trends and Potential Applications

Further optimization of purge-and-trap parameters and GC temperature programs can shorten analysis cycle times and boost laboratory productivity. Integration with high-resolution or tandem mass spectrometry could expand the scope to emerging contaminants. Portable P&T-GC/MS platforms may enable on-site water testing for rapid environmental assessments.

Conclusion

The combined Teledyne Tekmar Atomx XYZ and Agilent 7890B/5977B system reliably quantifies a broad range of VOCs in water at sub-ppb levels following MEE Method HJ639. The method delivers robust linearity, low MDLs, and excellent precision, making it well suited for routine environmental monitoring and regulatory compliance.