EPA-RCA: 9310: Gross Alpha and Beta Determination
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Official Method Name
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Gross Alpha and Gross Beta |
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Current Revision
| Step-86 |
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Media
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WATER |
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Instrumentation
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Alpha Gas Particle Counter |
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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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An aliquot of preserved water sample is evaporated to a small volume which is quantitatively transferred to a tared 2-inch stainless steel counting planchet. The sample is dried to a constant weight, re-weighed to determine dry mass, and is then counted for alpha and beta activity. The results are compared against standard curves to determine activities. |
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Scope and Application
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This method is applicable to the measurement of gross alpha and gross beta particle activities in surface and ground waters. |
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Applicable Concentration Range
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Alpha: 3pCi/L - * Beta: 4pCi/L - * (* Method does not specify an upper detection level.) |
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Interferences
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(A) Moisture absorbed by the sample residue is an interference because it obstructs counting and self-absorption characteristics. If a sample is counted in an internal proportional counter, static charge on the sample residue can cause erratic counting, thereby preventing an accurate count. (B) Nonuniformity of the sample residue in counting planchet interferes with the accuracy and precision of the method. (C) Sample density on the planchet area should be not more than 10 mg/cm 2 for gross alpha and not more than 20 mg/cm for gross beta. |
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Quality Control Requirements
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One blank per sample batch; duplicate sample every 10 samples; SS and SRM |
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Sample Handling
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Use plastic containers for collection of samples. Preserve samples to a pH of 2 with 1 N HNO3 at the time of collection. |
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Maximum Holding Time
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Samples collected without preservation, should be preserved within 5 days and then held in the original container for a minimum of 16 hr before analysis or transfer of the sample. |
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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