EPA-NERL: 415.3: Dissolved and Total Organic Carbon and UV Absorbance at 254 nm in Source Water and Drinking Water
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Official Method Name
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Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water |
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Current Revision
| Revision 1.2, Sept. 2009 |
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Media
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WATER |
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Instrumentation
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Total Organic Carbon 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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Brief Method Summary
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TOC is determined by removing inorganic carbon, oxidizing the remaining carbon to carbon dioxide using combustion or chemical oxidation with persulfate, and measuring the carbon dioxide produced using a conductivity detector or nondispersive infrared detector. DOC is determined similarly to TOC, but the sample is filtered through a 0.45 um filter prior to oxidation. UVA is measured by filtering a sample with a 0.45 um filter and measuring absorbance at 254 nm. SUVA is calculated by dividing UVA by DOC and multiplying by an appropriate unit correction factor as described in Section 12.2 of the method. |
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Scope and Application
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This method provides procedures for the determination of total organic carbon (TOC), dissolved organic carbon (DOC), and UV absorption at 254 nm (UVA), and Specific UV Absorbance (SUVA) in source waters and drinking waters. |
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Applicable Concentration Range
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0-50 mg/L calibration |
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Interferences
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(A) Carbon contamination from air and water: Foam and mist from the operation of water treatment plants introduce organic carbon into the air, as can petroleum products and dispersal of dust by work traffic. Laboratory water systems can become contaminated due to bacterial break through from resin beds, activated carbon, and filters. Air filtering systems and reduction of work traffic can reduce the level of organic carbon in the air. A 0.22 um water filter can be used to prevent bacterial contamination of water. In addition, all glassware must be scrupulously cleaned, and lab reagent and field blanks can be used to determine the success of contamination prevention measures. (B) Non-carbon contaminants: Source waters containing ionic iron, nitrates, nitrites, and bromide have been reported to interfere with measurements of UVA. Analysts should flag data if they suspect contamination from one of these interferences. (C) Chloride: Chloride exceeding 250 mg/L may interfere with persulfate oxidations methods. (D) Inorganic carbon: Inorganic carbon in the sample must be removed to determine organic carbon accurately. |
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Quality Control Requirements
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Each laboratory using the method is required to operate a formal quality control (QC) program. Specific QC requirements include an initial demonstration of laboratory capability (IDC) followed by regular analyses of continuing calibration checks (CCC), independent quality control samples (QCS), laboratory reagent blanks (LRB), field duplicates (FD), and laboratory fortified matrix samples (LFM). In addition, analysis of DOC and UVA requires the use of filter blanks (FB). |
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Sample Handling
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(A) DOC, UVA (SUVA) Samples: Collect samples for the analysis of DOC and UVA in glass bottles. Ship samples packed in ice or frozen gel packs. Samples for DOC must be received by the analyzing lab and filtered within 48 hours of collection, preserved to a pH at or below 2, stored at or below 6oC, and analyzed within 28 days of collection. UVA samples are filtered, stored below 6oC, and analyzed within 48 hours of collection (they are not acidified). (B) TOC Samples: Collect samples in glass bottles and preserve to a pH at or below 2 at the time of collection. Ship samples packed in ice or frozen gel packs. Samples preserved to a pH at or below 2, and stored at or below 6oC, must be analyzed within 28 days of collection. NOTE: When checking pH, do not place pH paper in the sample bottle as this may introduce contamination. |
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Maximum Holding Time
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TOC, DOC: 28 days. UVA: 48 hours |
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Relative Cost
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$51 to $200 |
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Sample Preparation Methods
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