Improved method for the determination of dissolved radium-226

Most of the current techniques for radium determination involve chemical separation of radium from major sample constituents by coprecipitation with barium or lead sulfate, followed by further radium purification. However, when samples contain biological materials, such as algae in wastewater from uranium millponds, or brine water from oil fields, the precipitation and purification processes become tedious and time-consuming. An improved method has been developed for the determination of radium-226 in such water samples, which also is applicable to natural waters. This method is based on a radon determination of alpha activity of the radon and its short-lived daughters in an alpha-scintillation cell. The radon-bubbler volume is either 90 millimeters for concentrated samples or 800 milliliters for dilute samples. For radium concentrations less than 1 picocurie per liter, 2 liters of water sample can be concentrated several-fold by simple evaporation, and decreased to 800 milliliters prior to deemanation. Because the process involves no chemical separations, chemical recoveries are nearly 100 percent. The lower limit of detection is 0.05 picocurie per liter for a 1-liter water sample and a counting time of 1000 minutes. 19 references, 3 figures, 3 tables