Volatile halogenated hydrocarbons - Separation of 26 volatile halogenated hydrocarbons in water on a fused silica capillary column

Importance of the Topic

Accurate determination of volatile halogenated hydrocarbons in water is essential for environmental monitoring, regulatory compliance and human health protection. These compounds often originate from industrial discharges, solvent use and agricultural applications. Their persistence and toxicity require sensitive and reliable analytical methods to detect trace levels in aqueous matrices.

Study Objectives and Overview

This application note demonstrates a gas chromatographic method capable of separating 26 volatile halogenated hydrocarbons in water within a 38 minute run time. The aim is to achieve baseline resolution of chlorinated, brominated and iodinated species using a fused silica capillary column under optimized temperature and flow conditions.

Methodology

The procedure involved direct injection of water samples onto a polar capillary column with the following steps:

• Initial oven temperature set at 60 °C
• Programmed ramp of 2 °C per minute up to 200 °C
• Hydrogen carrier gas at 75 kPa delivering a linear velocity of 32 cm/s
• Split injection at 200 mL/min and injector temperature at 200 °C
• Flame ionization detection at 280 °C

Used Instrumentation

• Gas chromatograph equipped with a 0.32 mm x 50 m fused silica capillary WCOT CP-Wax 57 CB column, 1.2 µm film thickness
• Hydrogen generator or cylinder for carrier gas
• Split/splitless injector and flame ionization detector

Main Results and Discussion

The method produced clear baseline separation of all 26 target analytes, including tetra- and trichlorinated methanes, mixed halogenated ethanes and propanes, and brominated cyclohexane. Elution order followed increasing boiling point and polarity. Peak shapes were sharp and symmetric, supporting accurate quantitation at low microgram per liter levels.

Benefits and Practical Applications

• Rapid analysis suitable for routine monitoring of drinking and surface waters
• High resolution allows simultaneous detection of structurally similar compounds
• Hydrogen carrier reduces run times and improves sensitivity compared with nitrogen
• Method supports quality assurance in environmental laboratories and regulatory agencies

Future Trends and Opportunities

Advances in column technology, such as shorter high-efficiency capillaries and novel stationary phases, will further reduce analysis times. Coupling with mass spectrometry can enhance selectivity for complex matrices. Automated sample preparation and on-site portable GC systems offer potential for real-time water quality screening.

Conclusion

This GC method on a CP-Wax 57 CB column effectively separates a broad range of volatile halogenated hydrocarbons in water within 38 minutes. It provides a robust, sensitive tool for environmental analysis and regulatory compliance.