EPA Method RSK175 Dissolved Gasses in Water Matrices using the Teledyne Tekmar HT3 Headspace Analyzer

The analysis of dissolved gases in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel contaminated area. The gases of concern include methane, ethane, and ethylene. These compounds are used to detect biodegradation in areas of concern such as landfills and remediation sites. Presence of the compounds is used to determine if natural contaminant attenuation and destruction are occurring at a specific site. For example, fuel hydrocarbons will break down to methane and chlorinated solvents will reduce to form ethylene and chloride (1).

Previous techniques for the analysis of dissolved gases used direct injections into the gas chromatograph. The water sample would be in a sealed vial with a certain amount of headspace. The vial would be heated and/or agitated to drive the gases into the headspace. The headspace was removed with a syringe and injected into the gas chromatograph. The Teledyne Tekmar HT3 is a Static and Dynamic Headspace Autosampler for gas chromatographs. The HT3 automates the analysis, from heating and agitating the vial, to the injection of headspace into the GC. This application demonstrates the capability of the HT3 to analyze dissolved gases in water.

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