ASTM: D3454: Radium-226 in Water
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Official Method Name
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Standard Test Method for Radium-226 in Water |
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Current Revision
| 1997 |
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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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This test method is based on the emanation and scintillation counting of radon-222, a gaseous daughter product of radium-226, from a solution. Radium-226 is collected from water by coprecipitation on a relatively large amount of barium sulfate. The barium-radium sulfate is decomposed by fuming with phosphoric acid, and the resulting glassy melt is dissolved by evaporation with dilute hydrochloric acid to form soluble barium-radium phosphates and chlorides. These salts are dissolved and the solution is stored for ingrowth of radon-222. After a suitable ingrowth period, the radon gas is removed from the solution by purging with gas and transferred to a scintillation counting chamber. About 4 h after radon-222 collection, the scintillation chamber is counted for alpha activity. The radium-226 concentration is calculated from the alpha count rate of radon-222 and its immediate daughters. |
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Scope and Application
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This test method covers the measurement of soluble, suspended, and total radium-226 in water in concentrations above 0.0037 Bq/L. This test method is not applicable to the measurement of other radium isotopes. This test method may be used for quantitative measurements by calibrating with a radium-226 standard, or for relative measurements by comparing the measurements made with each other. |
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Applicable Concentration Range
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0.0037 Bq/L |
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Interferences
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Only the gaseous alpha-emitting radionuclides interfere, namely, radon-219 and radon-220. Their half lives are 3.9 and 54.5 s respectively; their presence indicates the presence of their parents, radium-223 and radium-224. These short-lived radon isotopes decay before the radon-222 is counted; it is their alpha-emitting decay products that would interfere. These interferences are very rare in water samples but are frequently observed in certain uranium mill effluents. |
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Quality Control Requirements
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Whenever possible, the project leader, as part of the external quality control program, should submit quality control samples to the analyst along with routine samples in such a way that the analyst does not know which of the samples are the quality control samples. These external quality control samples which usually include duplicate and blank samples, should test sample collection and preparation as well as sample analysis whenever this is possible. In addition, analysts are expected to run internal quality control samples that will indicate to them whether the analytical procedures are in control. Both the external and internal quality control samples should be prepared in such a way as to duplicate the chemical matrix of the routine samples, insofar as this is practical. The quality control samples that are routinely used consist of five basic types: blank samples, replicate samples, reference materials, control samples, and spiked samples. |
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Sample Handling
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Collect the sample in accordance with the applicable standards as described in Practices D 3370. |
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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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