Standard Methods: 2340C: EDTA Titrimetric Method (Hardness)
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Official Method Name
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EDTA Titrimetric Method |
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Current Revision
| Standard Methods Online |
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Media
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WATER |
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Instrumentation
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Titration |
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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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A sample is titrated with EDTA at a pH of 10.0 +/- 0.1 using Eriochrome Black T or Calmagite indicator. Endpoint of red to blue. |
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Scope and Application
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This method determines the harndess of a water sample. |
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Applicable Concentration Range
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None Provided. |
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Interferences
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Reduce interference from metal ions by adding MgCDTA. Interference from heavy metals or polyphosphates is reduced by other inhibitors, i.e., NaCN or Na2S. Suspended or colloidal organic matter may also interfere with end point. Eliminate by evaporating the sample to dryness and heating in muffle furnace to oxidize organic matter. |
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Quality Control Requirements
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None. |
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Sample Handling
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Conduct titration at or near normal room temperature. Neutralize preserved sample to pH 7 with NaOH |
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Maximum Holding Time
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6 months after addition of nitric or sulfuric acid to pH <2 |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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