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An Improved Method for Determining Helium in Water.
MISSING :9 pages
The U.S. Bureau of Mines has developed an improved method for determining dissolved helium in water in the concentration range of 4.0 X 10-8 to 270 x 10-8 cm3 he (stp)/cm3 h2o. The method is a modification of a previously reported method that was developed for analyzing surface and subsurface waters in geochemical survey work. Water samples are collected in 500-cm3 stainless steel cylinders, and the dissolved gases in a sample are extracted into an evacuated cylinder of equal volume. After addition of 30 psig of nitrogen containing less than 2 ppb helium to the extracted gases, the resulting mixture is analyzed for helium using a helium-tuned mass spectrometer. The helium content of the water sample is determined from an empirical calibration that is established by analyzing standard solutions of helium in water. The accuracy of the method is +/- 7 pct for helium-in-water concentrations above 10 x 10-8 cm3 he (stp)/cm3 h2o.
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Page last reviewed: May 5, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division