ASTM_D_4191_-_15.pdf

Designation:D419115Standard Test Method forSodium in Water by Atomic Absorption Spectrophotometry1This standard is issued under the fixed designation D4191;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.Scope*1.1 This test method covers the determination of lowamounts of sodium in waters2having low solids content.Theapplicable range of this test method is from 0.20 to 3.0 mg/Lwhen using the 589.6-nm resonance line.This range may beextended upward by dilution of an appropriate aliquot ofsample or by use of the less-sensitive 330.2-nm resonance line(see Test Method D3561).Many workers have found that thistest method is reliable for sodium levels to 0.005 mg/L,but useof this test method at this low level is dependent on theconfiguration of the aspirator and nebulizer system available inthe atomic absorption spectrophotometer as well as the expe-rience and skill of the analyst.The precision and bias datapresented are insufficient to justify use of this test method inthe 0.005 to 0.20-mg/L range.1.2 This test method has been used successfully with spikedreagent water.It is the analysts responsibility to assure thevalidity of the test method to other low dissolved solidsmatrices.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.4 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:3D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 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 ConduitsD3561 Test Method for Lithium,Potassium,and SodiumIons in Brackish Water,Seawater,and Brines by AtomicAbsorption SpectrophotometryD4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology D1129.4.Summary of Test Method4.1 Sodium is determined by flame atomic absorption spec-trophotometry.The sodium content is determined by aspiratingthe low solids sample directly with no sample pretreatment.5.Significance and Use5.1 Sodium salts are very soluble,and sodium leached fromsoil and rocks tends to remain in solution.Water with a highratio of sodium to calcium is deleterious to soil structure.5.2 Sodium is not particularly significant in potable waterexcept for those persons having an abnormal sodiummetabolism,but water supplies in some areas contain sufficientsodium to be a factor in the planning of sodium-free diets.5.3 The use of sodium salts is common in industry;therefore,many industrial wastewaters contain significantquantities of sodium.For high-pressure boiler feed-water eventrace amounts of sodium are of concern.6.Interferences6.1 In the analysis of low-solids water,interferences areusually negligible.7.Apparatus7.1 Atomic Absorption Spectrophotometer for use at 589.6nm.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved Feb.1,2015.Published March 2015.Originallyapproved in 1982.Last previous edition approved in 2008 as D4191 08.DOI:10.1520/D4191-15.2Platte,J.A.,and Marcy,V.M.,“ANew Tool for the Water Chemist,”IndustrialWater Engineering,May 1965.3For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE1The manufacturers instructions should be followed for allinstrumental parameters.Wavelengths other than 589.6 nm may be usedonly if they have been determined to be equally suitable.7.2 Sodium Hollow-Cathode LampsMultielement hollowcathode lamps are available and also have been found satis-factory.7.3 Pressure-Reducing ValvesThe supplies of fuel andoxidant shall be maintained at pressures somewhat higher thanthe operating pressure of