RSK SOP 175 for Methane, Ethane, Ethene & Propane
Feb
15
Written by:
2/15/2013 12:00 AM
Indicator parameters for monitoring the progress of natural attenuation of hydrocarbon contaminated sites includes the analysis for low molecular weight hydrocarbon gases released by microbial action as heavier hydrocarbons are broken down. These are typically Methane, Ethane, Ethene & Propane. These light hydrocarbons are monitored in groundwater samples by a static heated headspace procedure. Water samples are heated in vials partially filled with the water sample. Upon reaching equilibrium, the headspace vapor over the water is subsampled and injected into a gas chromatograph equipped with a flame ionization detector. Upon separation of the components and combustion, the concentrations are determined from the proportional response of the charged combustion fragments to an electrical current in the detector. The light hydrocarbons can be measured to low ppb levels in water samples.