USGS-NWQL: R1141: Radium-226
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Official Method Name
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Radium-226, Dissolved, Radon Emanation Method |
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Current Revision
| 1976 |
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Media
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WATER |
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Instrumentation
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Alpha Scintillation |
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Method Subcategory
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Radiochemical |
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Method Source
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Citation
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Brief Method Summary
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The method is based on the isolation of radon-222 produced by radium-226 and measurement of the alpha activity of the radon and its short-lived daughters. The method is specific for radium-226. Radon is measured in a modification of the alpha scintillation cell of Lucas (1957). Dissolved radium in filtered water is collected by coprecipitation with barium sulfate. The precipitate is centrifuged and then dissolved in alkaline sodium diethylene triamine pentacetate solution. The solution is transferred to a radon bubbler, and any radon present is removed by purging with helium gas. Fresh radon is then allowed to grow in. After several days the ingrown radon is purged into an alpha scintillation cell, short-lived daughters are allowed to grow in, and the alpha-count rate is then determined. The radium-226 concentration in the original water sample is calculated from the radon determination on the basis of the rate of radon production with time. |
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Scope and Application
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The method is applicable to any water sample. |
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Applicable Concentration Range
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None given. |
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Interferences
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Method is normally specific for radium-226. Radium-223 and radium-224 produce radon-219 and radon-220, respectively. Neither interfere directly, but the 10.6 hr lead-212 from radon-220 has alpha-emitting daughters which could interfere. |
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Quality Control Requirements
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Not Included |
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Sample Handling
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Maximum Holding Time
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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