USGS-NWQL: O-7100-83: Suspended Organic Carbon (SOC) in Water
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Official Method Name
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Carbon, Organic, Suspended |
|---|---|
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Current Revision
| 1987 |
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Media
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WATER |
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Instrumentation
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Elemental Analyzer |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Methods for the Determination of Organic Substances in Water and Fluvial Sediments, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 5, Chapter A3 Edited by R.L. Wershaw, M.J. Fishman, R.R Grabbe, and L.E. Lowe |
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Brief Method Summary
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The sample is collected on a silver filter, acidified, purged to remove inorganic carbon, and oxidized with persulfate in an autoclave at 116-130 deg. C. The resultant carbon dioxide is measured by nondispersive infrared spectrometry. |
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Scope and Application
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This method is suitable for the analysis of suspended organic carbon (SOC) constituents found in natural waters, brines, and waste waters. The method is not suitable for the determination of volatile organic constituents. |
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Applicable Concentration Range
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0.2 - 50 (undiluted) |
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Interferences
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Inorganic forms of carbon usually present in most waters are readily converted to carbon dioxide when acidified but will interfere if the sample is not purged adequately. Purgeable organic compounds are lost during this step. Water samples containing large concentrations of reducing agents will interfere by decomposing the persulfate oxidant. |
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Quality Control Requirements
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Quality-control samples area analyzed at a minimum of one in every ten samples. These QC samples include at least one of each of the following: blanks, quality control samples, third party check solutions, replicates, and spikes. Correlation coefficients for calibration curves must be at least 0.99. QC samples must fall within 1.5 standard deviations of the mean value. If all of the data-acceptance criteria in the SOPs are met, then the analytical data are acceptable. |
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Sample Handling
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The silver filter is placed in a petri dish. The petri dish is covered in aluminum foil. Chill petri dish and sample at 4oC; ship immediately. |
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Maximum Holding Time
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14 days from login |
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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