Standard Methods: 3030 H: Nitric and Perchloric Acid Digestion
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Official Method Name
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Nitric Acid-Perchloric Acid Digestion of Samples |
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Current Revision
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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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When using more than 100 mL of sample during digestion, determine recovery for each matrix to verify method validity. If sample is not acidified, acidify to methyl orange end point with concentrated HNO3. To well-mixed sample add 5 mL concentrated HNO3, bring to a slow boil, and evaporate to 15-20 mL. Add 10 mL each of concentrated HNO3 and HClO4, and evaporate until dense fumes of HClO4 first appear. If solution does not clear, cover container and keep solution just boiling until it clears. If needed, add 10 mL concentrated HNO3 to complete digestion. Cool and dilute to 50 mL with water. Heat sample to almost boiling to expel any chlorine or oxides of nitrogen. Filter if needed. Pour filtrate and washings in volumetric flask. Cool, dilute to 100 mL mark, and mix. Remove aliquots or concentrate sample (see abstract in Method 3030-D) for analysis. If Pb needs to be determined in the presence of high amounts of SO4, dissolve PbSO4 precipitate as such: Add 50 mL 500 g NH4C2H3O2/600 mL water to container in which digestion was carried out and heat to boiling. Move container to wet all surfaces and dissolve any residue. Slowly draw solution through filter. Transfer filtrate to volumetric flask. Cool, dilute to 100 mL mark, and set aside for Pb determination. 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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