ASTM_D_6238_-_98_2011.pdf

Designation:D623898(Reapproved 2011)Standard Test Method forTotal Oxygen Demand in Water1This standard is issued under the fixed designation D6238;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.1.Scope1.1 This test method covers the determination of totaloxygen demand in the range from 100 to 100 000 mg/L,inwater and wastewater including brackish waters and brines(see6.5).Larger concentrations,or samples with high suspendedsolids,or both,may be determined by suitable dilution of thesample.1.1.1 Since the analysis is based on the change in oxygenreading of the carrier gas compared to that when a sample isintroduced(see 4.1),the measurement range is a function of theamount of oxygen in the carrier gas.The higher the desiredconcentration range,the more oxygen required in the carriergas.Under recommended conditions,the carrier gas concen-tration should be between two to four times the maximumdesired oxygen demand.1.1.2 The lower measurement range is limited by thestability of the baseline oxygen detector output.This signal isa function of the permeation system temperature,carrier gasflow rate,oxygen detector temperature,and reference sensorvoltage.Combined,these variables limit the minimum recom-mended range to 2 to 100 mg/L.1.1.3 The upper measurement range is limited by themaximum oxygen concentration in the carrier gas(100%).With the recommended conditions of carrier gas concentrationbeing two to four times the maximum oxygen demand,thislimits the maximum possible oxygen demand to between250 000 to 500 000 mg/L.However,as a practical applicationto water analysis,this test method will consider a maximumrange of 100 000 mg/L.1.2 This test method is applicable to all oxygen-demandingsubstances under the conditions of the test contained in thesample that can be injected into the reaction zone.The injectoropening limits the maximum size of particles that can beinjected.If oxygen-demanding substances that are water-insoluble liquids or solids are present,a preliminary treatmentmay be desired.These pretreatment methods are described inAnnex A2.1.3 This test method is particularly useful for measuringoxygen demand in certain industrial effluents and processstreams.Its application for monitoring secondary sewageeffluents is not established.Its use for the monitoring of naturalwaters is greatly limited by the interferences defined in Section6.1.4 In addition to laboratory analysis,this test method isapplicable to on-stream monitoring.Sample conditioning tech-niques for solids pretreatment applications are noted in AnnexA2.1.5 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D888 Test Methods for Dissolved Oxygen in WaterD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits(Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3856 Guide for Management Systems in LaboratoriesEngaged in Analysis of WaterD5789 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Organic Constituents(Withdrawn 2002)3D5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.06 on Methods forAnalysis forOrganic Substances in Water.Current edition approved May 1,2011.Published June 2011.Originallyapproved in 1998.Last previous edition approved in 2003 as D623898(2003).DOI:10.1520/D6238-98R11.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total oxygen demand(TOD)the amount of oxygenrequired to convert the elements in compounds to their moststable oxidized forms.4.Summary