Analysis of Drinking Water with the Agilent 8860 GC and 7697A Headspace Sampler

Significance of the Topic

The reliable detection of volatile halogenated hydrocarbons, aromatic compounds, and organophosphorus pesticides in drinking water is essential for environmental monitoring and regulatory compliance. Headspace sampling minimizes sample preparation while gas chromatography delivers high sensitivity, accuracy, and robustness for trace contaminants analysis.

Study Objectives and Overview

This study illustrates how a single Agilent 8860 gas chromatograph, combined with an Agilent 7697A headspace sampler, can be configured with three detectors to simultaneously analyze multiple classes of contaminants in water. The goal was to demonstrate system flexibility and performance across two workflows:

• Headspace sampling of volatile halogenated and aromatic hydrocarbons with flame ionization and electron capture detection.
• Liquid injection of organophosphorus pesticides with flame photometric detection.

Methodology and Instrumentation

The volatile organic compounds were introduced via headspace sampling at 70 °C equilibration, then split to two capillary columns (DB-624 Ultra Inert for aromatics with FID, HP-5ms Ultra Inert for halogenates with ECD) using an unpurged CFT splitter. Organophosphorus pesticides were injected in splitless mode on a DB-1701 column with FPD. Key parameters included:

• Equilibration time: 40 minutes; injection duration: 0.5 minutes.
• Carrier gas: nitrogen at constant flow (1 mL/min).
• Column oven programs optimized for each analyte class.

Instrumentation Used

• Agilent 8860 GC system
• Agilent 7697A headspace sampler
• Agilent J&W DB-624 Ultra Inert column (30 m × 0.25 mm, 1.4 µm)
• Agilent HP-5ms Ultra Inert column (30 m × 0.25 mm, 0.25 µm)
• Agilent DB-1701 column (30 m × 0.25 mm, 0.25 µm)
• Flame ionization detector (FID)
• Electron capture detector (ECD)
• Flame photometric detector (FPD+)
• Unpurged capillary flow splitter (CFT)

Main Results and Discussion

Chromatographic separation was achieved with excellent reproducibility: area percent RSD below 2.5% and retention time RSD below 0.02% for volatile hydrocarbons, and area RSD below 1.9% with retention time RSD under 0.02% for pesticides. Calibration linearity exceeded R² = 0.9994 for all analytes. The inert flow path and optimal detector configuration ensured sharp peaks and consistent quantitation across multiple sample types.

Benefits and Practical Applications

The demonstrated system offers:

• Multi-analyte capability on a single GC platform.
• Minimal sample preparation via headspace sampling.
• High sensitivity and reproducibility for regulatory analysis.
• Flexible detector configuration to address diverse contaminant classes.

Future Trends and Potential Applications

Emerging developments may include automated data processing with AI-driven peak identification, integration of microextraction techniques for lower detection limits, and the expansion of multi-detector GC systems for broader environmental and food safety screening. Real-time monitoring and remote instrumentation management will further enhance laboratory throughput and compliance.

Conclusion

The integration of the Agilent 8860 GC with a 7697A headspace sampler and three detectors delivers a versatile, high-performance solution for comprehensive drinking water analysis. This configuration provides reliable quantitation and streamlined workflow for both volatile organic compounds and pesticides, supporting environmental laboratories in meeting stringent quality standards.

References

1. Wang C.X., Zhang J.Q., Na S. 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. Agilent Technologies Application Note; 5991-2787EN.
2. Bureau of Environmental Protection of the People’s Republic of China. Water and Wastewater Monitoring Methods, 4th Edition.