EPA-NERL: 310.2: Alkalinity by Autoanalyzer
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Official Method Name
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Alkalinity (Colorimetric, Automated, Methyl Orange) |
|---|---|
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Current Revision
| Issued 1971; Editorial Revision 1974 |
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Media
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WATER |
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Instrumentation
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Automated Spectrophotometer |
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Method Subcategory
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Inorganic |
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Method Source
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Citation
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Brief Method Summary
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Methyl orange is used as the indicator in this method because its pH range is in the same range as the equivalence point for total alkalinity, and it has a distinct color change that can be easily measured. The methyl orange is dissolved in a weak buffer at a pH of 3.1, just below the equivalence point, so that any addition of alkalinity causes a loss of color directly proportional to the amount of alkalinity. |
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Scope and Application
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This automated method is applicable to drinking, surface, and saline waters; domestic and industrial wastes. |
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Applicable Concentration Range
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10 to 200 mg/L as CaCO3. |
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Interferences
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Sample turbidity and color may interfere with this method. Turbidity must be removed by filtration prior to analysis. Sample color that absorbs in the photometric range used will also interfere. |
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Quality Control Requirements
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None. |
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Sample Handling
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Samples should be refrigerated at 4oC and run as soon as practical. Do not open sample bottle before analysis. |
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Maximum Holding Time
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14 days. |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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None. |
