EPA: 7471B: Mercury in solid or semisolid waste using manual cold-vapor atomic absorption
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Official Method Name
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EPA Method 7471B (SW-846): Mercury in Solid or Semisolid Wastes (Manual Cold-Vapor Technique) |
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Current Revision
| Revision 2, February 2007 |
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Media
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VARIOUS |
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Instrumentation
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Cold Vapor Atomic Absorption |
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Method Subcategory
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Organic+Inorganic |
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Method Source
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Citation
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Brief Method Summary
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Weigh a 0.5 - 0.6 g-aliquot of a well homogenized sample and place in the bottom of a BOD bottle or other appropriate analysis vessel. Add 5 mL of reagent water and 5 mL of aqua regia. Heat 2 min at 95 ± 3 ˚C. Cool; then add 50 mL of reagent water and 15 mL of potassium permanganate solution to each sample and let stand at least 15 min. Add additional portions of permanganate solution, if needed, until the purple color persists for at least 15 min. Ensure that equal amounts of permanganate are added to standards and blanks. Mix thoroughly, then heat for 30 min at 95 ± 3 ˚C. Cool and add 6 mL of sodium chloride hydroxylamine sulfate to reduce the excess permanganate. Add 55 mL of reagent water. Treating each bottle individually, add 5 mL of stannous sulfate and immediately attach the bottle to the aeration apparatus. The mercury vapor passes through a cell positioned in the light path of an atomic absorption spectrophotometer. Absorbance (peak height) at the 253.7-nm wavelength is measured as a function of mercury concentration. |
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Scope and Application
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This method covers the determination of total mercury (organic and inorganic) in soils, sediments, bottom deposits, and sludge-type materials. |
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Applicable Concentration Range
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Not provided. |
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Interferences
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(A) Solvents, reagents, glassware, and other sample processing hardware contamination: Analyze method blanks, selection of clean reagents and or purification of solvents by distillation in all-glass systems may be necessary. (B) Sulfide interference: Potassium addition. Concentrations as high as 20 mg/Kg of sulfide, as sodium sulfide, do not interfere with the recovery of added inorganic mercury in reagent water. (C) Copper interference: No remedy however copper concentrations as high as 10 mg/Kg had no effect on recovery of mercury from spiked samples. (D) High chloride interference: Add additional permanganate (as much as 25 mL) to block oxidation to free chlorine which also absorbs radiation of 254 nm. (E) Chlorine interference: Add an excess of hydroxylamine sulfate reagent (25 mL), purge the dead air space in the bottle before adding stannous sulfate or allow the sample to stand for at least an hour under a hood (without active purging) to remove the chlorine. (F) Certain volatile organic material interference: Use preliminary run to detect. No remedy. |
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Quality Control Requirements
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Method blank, Laboratory control standard, Matrix spike, Matrix spike duplicate |
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Sample Handling
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Sample containers must be prewashed with detergents, acids, and reagent water. Glass, plastic, and polytetraflouroethylene (PTFE) containers are suitable in most cases. |
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Maximum Holding Time
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28 days. Refrigerate non-aqueous samples if not analyzed immediately |
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Relative Cost
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Sample Preparation Methods
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All samples must be subjected to an appropriate dissolution step prior to analysis. |
