EPA Method 420.4

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EPA Method 420.4:
Total recoverable phenolics in water by semi-automated colorimetry. Official Name: Determination of Total Recoverable Phenolics by Semi-Automated Colorimetry

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.

This method covers the determination of phenolic materials in drinking, ground, surface, and saline waters, and domestic and industrial wastes.

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.

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.

QC Requirements:
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.

Maximum Holding Time:
28 days



2-500 ug/L, with working ranges of 2-200 and 10-500

Precision was assesed through interlaboratory analyses using a reagent water matrix and values were presented in mg Phenol/L.

MDL is established using reagent water fortified at a concentration of two to three times the estimated instrument detection limit. Seven replicate aliquots of the fortified reagent water are processed through the entire analytical method.

Revision Number:
Revision 1.0, August 1993

Test Description:
Total Recoverable Ph

Report Number:

Instrument used for this test: