Standard Methods: 3030 F: Nitric and Hydrochloric Acid Digestion
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Official Method Name
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Nitric Acid-Hydrochloric Acid Digestion of Samples |
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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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Preparatory Procedure |
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Method Subcategory
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Sampling/Preparation |
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Method Source
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Citation
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Brief Method Summary
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This method should be used for digesting samples containing Ag. For samples with Ag concentrations > 1 mg/L, dilute to < 1 mg/L for flame AA methods and < 25 ug/L for electrothermal analysis. When using more than 100 mL of sample during digestion, determine recovery for each matrix to verify method validity. I. Total HNO3/HCl: Determine sample volume for the expected metals concentration (see abstract in Method 3030-E). To well-mixed sample add 3 mL concentrated HNO3 and evaporate to < 5 mL. Cool and add 5 mL concentrated HNO3. Cover container and reflux over hot plate. Continue this process until digestion is complete and total volume is < 5 mL. Add 10 mL 1+1 HCl and 15 mL water per 100 mL final volume. Heat for 15 minutes to dissolve precipitate or residue. Cool and rinse container walls with water. Filter, centrifuge, or let stand overnight to remove insoluble material. II. Recoverable HNO3/HCl: To well-mixed sample add 2 mL 1+1 HNO3 and 10 mL 1+1 HCl, and evaporate to < 25 mL. Cool then filter, centrifuge, or let stand overnight to remove insoluble material. Bring volume to 100 mL and mix. Samples totally digested by acid digestion techniques yield comparable precision and bias, however, the minimal amount of acid should be used in the digestion as acid adds metals to the sample. |
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Scope and Application
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This method is applicable to the digestion of metals in waste and wastewater samples. |
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Applicable Concentration Range
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Interferences
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Metals introduced during preliminary treatment from equipment common to environmental labs. |
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Quality Control Requirements
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Check reagent grade acids for purity. Process blanks through all digestion and filtration steps. |
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Sample Handling
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Collect sample in plastic or glass container which has been rinsed with 1+1 HNO3. Adjust the pH of the sample to < 2 with HNO3. For dissolved metals, filter samples immediately. Analyze within 6 months. |
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Maximum Holding Time
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6 months |
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Relative Cost
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Less than $50 |
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Sample Preparation Methods
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