Analysis of Volatile Halogenated and Aromatic Hydrocarbons and Organophosphorus Pesticides in Water with a Versatile Agilent 7890B Gas Chromatography System and an Agilent 7697A Headspace Sampler

Significance of the Topic

Aqueous contamination by volatile halogenated and aromatic hydrocarbons and organophosphorus pesticides poses serious risks to human health and ecosystems. Routine monitoring of these analytes in water is essential for environmental protection, regulatory compliance, and early detection of pollution events.

Objectives and Study Overview

This study evaluates a unified analytical workflow for simultaneous determination of volatile hydrocarbons and organophosphorus pesticides in water. An Agilent 7890B gas chromatograph equipped with three detector channels (FID, ECD and FPD) and an Agilent 7697A headspace sampler was configured to achieve high sensitivity, reproducibility and throughput with minimal sample preparation.

Methodology and Instrumentation

The method combines static headspace sampling for volatile hydrocarbons with automated liquid sampling for pesticides. Key instrumentation and conditions include

• Agilent 7890B GC with three inlets feeding FID, ECD and FPD detectors
• Agilent 7697A headspace sampler operating at 70 °C with 40 min equilibration and 1 mL loop volume
• Columns: HP-5 MS UI and DB-FFAP for hydrocarbons; DB-1701 for pesticides
• Carrier gas: nitrogen at constant flow rates
• Optimized headspace parameters: temperature and equilibration time
• Inert splitless inlet liner and splitter to minimize analyte loss and degradation

Key Results and Discussion

Optimization experiments demonstrated that a sample temperature of 70 °C and 40 minutes equilibration provided maximum headspace response for target compounds. Hydrocarbon analysis achieved repeatability below 2.0% RSD and recoveries of 97.3–102.7%. Organophosphorus pesticide quantitation yielded correlation coefficients above 0.9996, RSDs below 2.8% and recoveries between 90.4% and 98.8%. Enhanced FPD thermal control improved phosphorus sensitivity to 45 fgP per second.

Benefits and Practical Applications

The combined GC and headspace system offers

• High automation and throughput for routine water analysis
• Simultaneous multi-analyte detection in a single injection
• Robust quantitation with low detection limits
• Reduced sample preparation and solvent use
• Compliance with environmental monitoring standards

Future Trends and Potential Applications

Emerging developments may include

• Integration with mass spectrometric detectors for extended analyte scope
• On-line and in-situ sampling technologies
• Miniaturized and portable GC systems for field analysis
• Green analytical techniques using alternative solvents and materials
• Advanced data processing and machine learning for real-time monitoring

Conclusion

The Agilent 7890B GC configured with FID, ECD and FPD detectors and the 7697A headspace sampler delivers a versatile, sensitive and reproducible workflow for environmental water analysis of volatile hydrocarbons and organophosphorus pesticides. The method meets stringent performance criteria and supports high-throughput monitoring.

References

1. Kolb B and Ettre LS Static Headspace-Gas Chromatography Theory and Practice Second Edition John Wiley Sons 2006
2. Bushey J Thermal zone considerations for the Agilent 7697A headspace sampler Agilent Technologies publication 5990-9892EN
3. Bureau of Environmental Protection of the People’s Republic of China Water and Wastewater Monitoring Methods Fourth Edition
4. US EPA Method 614.1 The Determination of Organophosphorus Pesticides in Municipal and Industrial Wastewater