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TM_D_6647_
_01_2011
Designation:D664701(Reapproved 2011)Standard Test Method forDetermination of Acid Soluble Iron Via Atomic Absorption1This standard is issued under the fixed designation D6647;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 the acidsoluble iron content of granular and powdered activatedcarbons,using an atomic absorption spectroscopy method bydirect aspiration.Hydrochloric acid is used to extract the iron.This test method is not directly usable to determine the totaliron concentration of a sample.1.2 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 a specifichazard statement,see Section 8.2.Referenced Documents2.1 ASTM Standards:2D2652 Terminology Relating to Activated CarbonD1193 Specification for Reagent WaterE11 Specification for Woven Wire Test Sieve Cloth and TestSievesE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE287 Specification for Laboratory Glass Graduated BuretsE288 Specification for Laboratory Glass Volumetric FlasksE300 Practice for Sampling Industrial Chemicals2.2 NIST Publication:Circular 602 Testing of Glass Volumetric Apparatus33.Terminology3.1 Definitions Terms relating to this standard are definedin Terminology D2652.3.1.1 atomic absorptionin flame atomic absorption spec-trometry,a sample is aspirated into a flame and atomized.Alight beam is directed through the flame,into a monochroma-tor,and onto a detector that measures the amount of lightabsorbed by the atomized element in the flame.Because eachmetal has its own characteristic absorption wavelength,asource lamp of that element is used.The amount of energy atthe characteristic wavelength absorbed in the flame is propor-tional to the concentration of the element in the sample over alimited concentration range.4.Summary of Test Method4.1 Arepresentative sample of the material to be analyzed iscollected according to E300.A known weight of the sample isground until 95%or more of the sample passes 325 mesh.Theground sample is oven dried,and then mixed with a dilutehydrochloric acid.The solution is boiled for 5 minutes toconvert the iron into a soluble chloride,and then cooled andfiltered.The filter cake is washed with water.Then the filtrateis transferred quantitatively to a beaker.The concentration ofiron in the filtrate is measured by atomic absorption against aset of standards.The acid soluble iron concentration is thencalculated against the weight of the original sample.5.Significance and Use5.1 In certain applications,such as acid purification,acidicfood or chemical purification or decolorization,or otherapplications wherein iron may be leached out of the carbon,theuse of acid-washed carbons will reduce or eliminate colorpickup in the effluent or in the product.The acid soluble ironcontent is usually specified by the carbon supplier to preventunacceptable levels of iron leach occurring.5.2 Detection limits,sensitivity,and optimum ranges willvary with the models of atomic absorption spectrophotometers.General instrumental parameters are as follows:5.2.1 Iron hollow cathode lamp.5.2.2 Wavelength:248.3 nm.5.2.3 Fuel:acetylene(high purity).5.2.4 Oxidant:air(from compressed air line,laboratorycompressor,or a cylinder of compressed airall need to beclean and dry).5.2.5 Type of flame:oxidizing.5.2.6 The following lines may also be used:1This test method is under the jurisdiction of ASTM Committee D28 onActivated Carbon and is the direct responsibility of Subcommittee D28.02 on LiquidPhase Evaluation.Current edition approved Sept.1,2011.Published November 2011 Originallyapproved in 2001.Last previous edition approved in 2006 as D6647 01(2006).DOI:10.1520/D6647-01R11.2For 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.3Available from National Institute of Standards and Technology(NIST),100Bureau Dr.,Stop 1070,Gaithersburg,MD 20899-1070,http:/www.nist.gov.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 248.8 nm Relative Sensitivity 2271.9 nm Relative Sensitivity 4302.1 nm Relative Sensitivity 5252.7 nm Relative Sensitivity 6372.0 nm Relative Sensitivity 105.3 The method,as written,is intended for carbons havingan acid soluble iron content of 0.0030 to 0.050%For carbonshaving higher iron contents,larger dilutions or smaller aliquotsmay be used.5.4 The user