EPA-ORD / EPA-OST: 420.4: Total recoverable phenolics in water by semi-automated colorimetry
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Official Method Name
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Determination of Total Recoverable Phenolics by Semi-Automated Colorimetry |
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Current Revision
| Revision 1.0, August 1993 |
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Media
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WATER |
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Instrumentation
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Colorimeter |
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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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Method 420.4: Determination of Total Recoverable Phenolics by Semi-Automated Colorimetry, Revision 1.0, August 1993. Edited by James W. O'Dell. EPA Environmental Monitoring Systems Laboratory, Office of Research and Development, Cincinnati, OH 45268. |
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Brief Method Summary
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This semi-automated method is based on the distillation of phenol and subsequent reaction of the distillate with alkaline ferricyanide and 4-aminoantipyrine to form a red complex which is measured at 505 or 520 nm. Color response of phenolic materials with 4-aminoantipyrine is not the same for all compounds. Because phenolic type wastes usually contain a variety of phenols, it is not possible to duplicate a mixture of phenols to be used as a standard. For this reason, phenol has been selected as a standard and any color produced by the reaction of other phenolic compounds is reported as phenol. This value will represent the minimum concentration of phenolic compounds present in the sample. Reduced volume versions of this method that use the same reagents and molar ratios are acceptable provided they meet the quality control and performance requirements stated in the method. |
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Scope and Application
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This method covers the determination of phenolic materials in drinking, ground, surface, and saline waters, and domestic and industrial wastes. |
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Applicable Concentration Range
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2-500 ug/L, with working ranges of 2-200 and 10-500 |
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Interferences
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Interferences from sulfur compounds are eliminated by acidifying the sample to a pH of 4.0 and aerating briefly by stirring. Oxidizing agents such as chlorine, detected by the liberation of iodine upon acidification in the presence of potassium iodide, are removed immediately after sampling by the addition of an excess of ferrous ammonium sulfate. If chlorine is not removed, the phenolic compounds may be partially oxidized and the results may be low. Background contamination from plastic tubing and sample containers is eliminated by filling the wash receptacle by siphon (using Kel-F tubing) and using glass tubes for the samples and standards. Method interferences may be caused by contaminants in the reagent water, reagents, glassware, and other sample processing apparatus that bias analyte response. |
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Quality Control Requirements
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Each laboratory using this method is required to operate a formal quality control (QC) program. The minimum requirements of this program consist of an initial demonstration of laboratory capability, and the periodic analysis of laboratory reagent blanks, fortified blanks and other laboratory solutions as a continuing check on performance. The laboratory is required to maintain performance records that define the quality of the data that are generated. |
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Sample Handling
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Samples should be collected in glass bottles only. All bottles must be thoroughly cleansed and rinsed with reagent water. Volume collected should be sufficient to insure a representative sample, allow for replicate analysis (if required), and minimize waste disposal. Samples must be preserved at time of collection with H2SO4 to a pH of <2 and cooled to 4oC. Samples should be analyzed as soon as possible after collection. If storage is required, preserved samples are maintained at 4oC. |
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Maximum Holding Time
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28 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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