ASTM_D_4691_-_11.pdf

Designation:D469111Standard Practice forMeasuring Elements in Water by Flame Atomic AbsorptionSpectrophotometry1This standard is issued under the fixed designation D4691;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 practice covers general considerations for thequantitative determination of elements in water and wastewater by flame atomic absorption spectrophotometry.Flameatomic absorption spectrophotometry is simple,rapid,andapplicable to a large number of elements in drinking water,surface waters,and domestic and industrial wastes.Whilesome waters may be analyzed directly,others will requirepretreatment.1.2 Detection limits,sensitivity,and optimum ranges of theelements will vary with the various makes and models ofsatisfactory atomic absorption spectrometers.The actual con-centration ranges measurable by direct aspiration are given inthe specific test method for each element of interest.In themajority of instances the concentration range may be extendedlower by use of electrothermal atomization and converselyextended upwards by using a less sensitive wavelength orrotating the burner head.Detection limits by direct aspirationmay also be extended through sample concentration,solventextraction techniques,or both.Where direct aspiration atomicabsorption techniques do not provide adequate sensitivity,theanalyst is referred to Practice D3919 or specialized proceduressuch as the gaseous hydride method for arsenic(Test MethodsD2972)and selenium(Test Methods D3859),and the coldvapor technique for mercury(Test Method D3223).1.3 Because of the differences among various makes andmodels of satisfactory instruments,no detailed operating in-structions can be provided.Instead the analyst should followthe instructions provided by the manufacturer of a particularinstrument.1.4 The values stated in either SI or inch-pound units are tobe regarded as the standard.The values given in parenthesesare for information only.1.5 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.For specific hazardstatements see Section 9.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2972 Test Methods for Arsenic in WaterD3223 Test Method for Total Mercury in WaterD3370 Practices for Sampling Water from Closed ConduitsD3859 Test Methods for Selenium in WaterD3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD4453 Practice for Handling of High Purity Water SamplesD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE178 Practice for Dealing With Outlying ObservationsE520 Practice for Describing Photomultiplier Detectors inEmission and Absorption SpectrometryE863 Practice for Describing Atomic Absorption Spectro-metric Equipment(Withdrawn 2004)33.Terminology3.1 Definitions:3.1.1 For definition of terms used in this practice,refer toTerminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 absorbance,nthe logarithm to the base 10 of thereciprocal of the transmittance(T).A=log10(1/T)=log10T.3.2.2 absorptivity,nthe absorbance(A)divided by theproduct of the sample path length(b)and the concentration(c).a=A/bc.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.05 on Inorganic Constituents inWater.Current edition approved Sept.1,2011.Published September 2011.Originallyapproved in 1987.Last previous edition approved in 2007 as D4691 02(2007).DOI:10.1520/D4691-11.2For 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.*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 3.2.3 atomic absorption,nthe absorption of electromag-netic radiation by an atom resulting in the elevation ofelectrons from their ground states to excited states.3.2.3.1 DiscussionAtomic-absorption spectrophotometryinvolves the measurement of light absorbed by atoms ofinterest as a function of the concentration of those atoms in aparticular solution.3.2.4 detection limit,nin atomic absorption is a functionof the sensitivity and the s