Sample Preparation And Calculations For Dissolved Gas Analysis
1.1 Sample Preparation and Calculations for Dissolved Gas Analysis in Water Samples Using a GC Headspace Equilibration Technique, EPA National Risk Management Research Laboratory, RSKSOP-175, Rev.2, May 2004.
1.2 Light Hydrocarbons in Aqueous Samples via Headspace and Gas Chromatography with Flame Ionization Detection (GC/FID), Pennsylvania Department of Environmental Protection Bureau of Laboratories, PA-DEP 3686, Rev.0, April 2012.
1.3 Lange’s Handbook of Chemistry, 14th edition (1992), McGraw Hill.
1.4 Gas Encyclopedia, Air Liquide, online edition (2009).
2.0 SCOPE AND APPLICATION
2.1 Samples reported using this procedure reference the sample preparation SOP commonly referred to as “RSK-175” for use in West Virginia. The procedure is automated and simplified by using the PADEPs Bureau of Laboratories procedure.
2.2 This is a gas chromatographic method used to determine the following gases dissolved in water.
Name CAS Registry No. Formula
Methane 74-82-8 CH4
Ethane 74-84-0 C2H6
Propane 74-98-6 C3H8
Ethene (Ethylene) 74-85-1 C2H4
3.0 SUMMARY OF METHOD
3.1 A portion of a water sample is added to a closed vial, heated, pressurized, and the headspace is injected into the GC using a specially designed sampler. Analytes are detected using a Flame Ionization Detector (FID). The amount of gas in the original liquid sample is directly proportional to the amount of gas in the headspace of a closed vessel.
3.2 Standards are prepared by saturating a solution…