USGS-NWQL: I-5447: Magnesium, recoverable-from-bottom-material, dry wt, FLAA
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Official Method Name
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Magnesium, atomic absorption spectrometric, direct |
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Current Revision
| 1985 |
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Media
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SOILS/SEDIMENT |
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Instrumentation
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Flame Atomic Absorption |
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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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Methods for the Determination of Inorganic Substances in Water and Fluvial Sediments, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 5, Chapter A1 Edited by Marvin J. Fishman and Linda C. Friedman |
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Brief Method Summary
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Magnesium is determined by flame atomic absorption spectrometry (Fishman and Downs, 1966). Lanthanum chloride is added to mask interferences. This procedure may be automated by the addition of a sampler, a proportioning pump, and either a strip-chart recorder or a printer or both. |
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Scope and Application
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This method may be used to analyze bottom material containing at least 10 mg/kg of magnesium. Prepared sample solutions containing more than 50 mg/L to be diluted. Recoverable magnesium in bottom material needs to undergo preliminary digestion-solubilization by method 1-5485 before being determined. |
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Applicable Concentration Range
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at least 10 mg/kg magnesium |
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Interferences
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The interference caused by aluminum concentrations greater than 2,000 ug/L is masked by addition of lanthanum. Because low magnesium values result if the pH of the sample is above 7, standards are prepared in hydrochloric acid solution and samples are preserved in the field with use of nitric acid solution. Nitrate, sulfate, and silica interfere, but in the presence of lanthanum chloride-hydrochloric acid solution at least 2,000 mg/L, 1,000 mg/L, and 200 mg/L, respectively, can be tolerated. The addition of nitric acid at the time of collection to preserve the samples causes no problem in the following procedure. Sodium, potassium, and calcium cause no interference at concentrations less than 400 mg/L. |
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Quality Control Requirements
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Calibrate instrument using calibration standards (CAL). Quality control samples (QCS) and laboratory blanks (LB) analyzed at a minimum of I each after every 10 samples |
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Sample Handling
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Container Description: 500 mL Polypropylene bottle, wide-mouth. Treatment and Preservation: No treatment, preservation or special shipping requirements. |
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Maximum Holding Time
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180 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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I-5485 |
