The American Society for Testing and Materials (ASTM) Method D8028 is a method to determine dissolved gases in water.  The method describes calibration and sampling techniques.  One of the recommendations is to ensure the sample is sealed in order to safeguard the integrity of the sample.  This recommendation is taken from United States Environmental Protection Agency (USEPA) Method 5030C used for the sampling of volatile organic compounds in water.  Many environmental labs currently open their dissolved gas samples in order to place them in a headspace vial for sampling and analysis.  This application will compare the efficacy of ensuring the sample is sealed versus opening the sample and pouring it into the sample vial for analysis.