Automated Determination of Dissolved Gases in Water By Headspace Calibration of Mixed Gases

Due to the expansion of natural gas drilling through horizontal fracturing, there has been increased interest in the RSK-175 Standard Operating Procedure (SOP) for the determination of dissolved gases in water. Since RSK-175 is an SOP and not a formal EPA method; laboratories have employed different approaches in order to calibrate for the dissolved gases. This paper will discuss calibration by using static headspace sampling of vials spiked with different volumes of mixed gases. Furthermore, the precision and accuracy of the calibration will be established by headspace screening of mixed gas standards and also by examining known concentrations of dissolved gases and back calculating experimental results using the Henry’s Constant and the saturated gas calculation.