ASTM_D_1252_-_06_2020.pdf

Designation:D125206(Reapproved 2020)Standard Test Methods forChemical Oxygen Demand(Dichromate Oxygen Demand)ofWater1This standard is issued under the fixed designation D1252;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 These test methods cover the determination of thequantity of oxygen that certain impurities in water willconsume,based on the reduction of a dichromate solutionunder specified conditions.The following test methods areincluded:Test Method A Macro COD by Reflux Digestion and TitrationTest Method B Micro COD by Sealed Digestion and Spectrometry1.2 These test methods are limited by the reagents employedto a maximum chemical oxygen demand(COD)of 800 mg/L.Samples with higher COD concentrations may be processed byappropriate dilution of the sample.Modified procedures ineach test method(Section 15 for Test Method A,and Section24 for Test Method B)may be used for waters of low CODcontent(50 mg/L).1.3 As a general rule,COD results are not accurate if thesample contains more than 1000 mg/LCl.Consequently,thesetest methods should not be applied to samples such asseawaters and brines unless the samples are pretreated asdescribed in Appendix X1.1.4 This test method was used successfully on a standardmade up in reagent water.It is the users responsibility toensure the validity of these test methods for waters of untestedmatrices.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific hazard statements,see Section 8,15.6,and 24.5.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3223 Test Method for Total Mercury in WaterD3370 Practices for Sampling Water from Flowing ProcessStreamsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD5905 Practice for the Preparation of Substitute WastewaterE60 Practice for Analysis of Metals,Ores,and RelatedMaterials by SpectrophotometryE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard,refer toTerminology D1129.3.2 Definitions of Terms Specific to This StandardTheterm“oxygen demand”(COD)in these test methods is definedin accordance with Terminology D1129 as follows:3.2.1 oxygen demand,nthe amount of oxygen requiredunder specified test conditions for the oxidation of water borneorganic and inorganic matter.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.06 on Methods forAnalysis for Organic Substances in Water.Current edition approved Jan.1,2020.Published January 2020.Originallyapproved in 1953.Last previous edition approved in 2012 as D1252 06(2012)1.DOI:10.1520/D1252-06R20.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.4.Summary of Test Methods4.1 Most organic and oxidizable inorganic substances pres-ent in water are oxidized by a standard potassium dichromatesolution in 50%sulfuric acid(vol/vol).The dichromateconsumed(Test Method A)or tri-valent chromium produced(Test Method B)is determined for calculation of the CODvalue.4.2 The oxidation of many otherwise refractory organics isfacilitated by the use of silver sulfate that acts