ASTM_E_1184_-_10.pdf

Designation:E118410Standard Practice forDetermination of Elements by Graphite Furnace AtomicAbsorption Spectrometry1This standard is issued under the fixed designation E1184;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 practice covers a procedure for the determinationof microgram per millilitre(g/mL)or lower concentrations ofelements in solution using a graphite furnace attached to anatomic absorption spectrometer.A general description of theequipment is provided.Recommendations are made for pre-paring the instrument for measurements,establishing optimumtemperature conditions and other criteria which should result indetermining a useful calibration concentration range,andmeasuring and calculating the test solution analyte concentra-tion.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.3 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.Specific safetyhazard statements are given in Section 9.2.Referenced Documents2.1 ASTM Standards:2E50 Practices for Apparatus,Reagents,and Safety Consid-erations for Chemical Analysis of Metals,Ores,andRelated MaterialsE131 Terminology Relating to Molecular SpectroscopyE135 Terminology Relating to Analytical Chemistry forMetals,Ores,and Related MaterialsE406 Practice for Using Controlled Atmospheres in Spec-trochemical AnalysisD1193 Specification for Reagent Water3.Terminology3.1 Refer to Terminologies E131 and E135 for the definitionof terms used in this practice.3.2 Definitions of Terms Specific to This Standard:3.2.1 atomizationthe formation of ground state atoms thatabsorb radiation from a line emission source.The atomizationprocess in graphite furnace atomic absorption spectrometry(GF-AAS)analysis is covered in 6.2.3.2.2 pyrolysisthe process of heating a specimen to atemperature high enough to remove or alter its original matrix,but not so high as to volatilize the element to be measured.Thepurpose of the pyrolysis step in GF-AAS analysis is to removeor alter the original specimen matrix,thereby reducing oreliminating possible interferences to the formation of groundstate atoms that are formed when the temperature is increasedduring the atomization step.Many publications and referenceswill refer to pyrolysis as charring or ashing.3.2.3 pyrolytic graphite coatinga layer of pyrolytic graph-ite that coats a graphite tube used in GF-AAS analysis.Pyrolytic graphite is formed by pyrolizing a hydrocarbon,forexample,methane,at 2000 C.3.2.4 rampinga slow,controlled increase of the tempera-ture in the graphite tube.Ramping will provide for an efficientbut not too rapid removal or decomposition of the specimenmatrix.Most graphite furnaces allow for ramping during thedrying,pyrolysis,and atomization steps.It is usually employedduring the drying and pyrolysis steps.However,some instru-ment manufacturers may recommend ramping during theatomization step depending on the specimen matrix and theelement being measured(for example,the analysis of cadmiumor lead in hair or blood).The power supplies for mostinstruments also allow the rate of the temperature increase tobe varied.4.Significance and Use4.1 This practice is intended for users who are attempting toestablish GF-AAS procedures.It should be helpful for estab-lishing a complete atomic absorption analysis program.5.Theory of Atomic Absorption Spectrometry(AAS)5.1 In flame atomic absorption spectrometry(Flame-AAS),a test solution is aspirated into a flame through which passes1This practice is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals,Ores,and Related Materials and is the direct responsibility ofSubcommittee E01.20 on Fundamental Practices.Current edition approved June 1,2010.Published August 2010.Originallyapproved in 1987.Last previous edition approved in 2002 as E1184 02.DOI:10.1520/E1184-10.2For 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 States1 radiation from a line emission source of the element sought.The radiation of the element sought is absorbed in proportionto the concentration of its neutral atoms present in the flame.The concentration of the analyte is obtained by comparison tocalibrations.5.2 The theoretical basis for using atomic absorption todeterm