1、Designation: D8186 18Standard Test Method forMeasurement of Impurities in Graphite by ElectrothermalVaporization Inductively Coupled Plasma Optical EmissionSpectrometry (ETV-ICP OES)1This standard is issued under the fixed designation D8186; the number immediately following the designation indicates
2、 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 measurement of mass
3、fractions of the elements silver (Ag), aluminum (Al), arsenic(As), boron (B), barium (Ba), berylium (Be), bismuth (Bi),calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr),copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium(Mg), manganese (Mn), molybdenum (Mo), sodium (Na),nickel (Ni),
4、phosphorus (P), lead (Pb), sulfur (S), antimony(Sb), silicon (Si), tin (Sn), strontium (Sr), titanium (Ti),vanadium (V), tungsten (W), yitrium (Y), zinc (Zn), andzirconium (Zr) in graphite.1.2 Provided that an appropriate validation procedure iscarried out, this test method is also applicable to oth
5、er carbonmaterials such as coal, coke, carbon black, graphite-felt,graphite-foil, graphite-foam, and fiber reinforced carbon-carbon composites.1.3 This test method is applicable to element contents fromapproximately 0.0001 mgkg to 1000 mgkg (0.1 ppmw to1000 ppmw), depending on element, wavelength, m
6、easure-ment parameters, and sample mass.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses after SI units areprovided for information only and are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, as
7、sociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally
8、recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specificat
9、ion for Reagent Water2.2 ISO Standards:3ISO 5725-2 Accuracy (trueness and precision) of measure-ment methods and resultsPart 2: Basic method for thedetermination of repeatability and reproducibility of astandard measurement method3. Terminology3.1 Definitions:3.1.1 ETV, nelectrothermal vaporization.
10、3.1.2 ICP OES, ninductively coupled plasma opticalemission spectrometry.4. Summary of Test Method4.1 The ETV unit consists of an electrically heated graphitetube furnace. Graphite boats which fit into the graphite tube areused for inserting the sample, crushed and milled if necessary,into the furnac
11、e. Handling of graphite boats is preferably doneusing an automated system. One end of the furnace, which issealed with a movable door, is used for inserting the graphiteboats (furnace inlet). The other end of the furnace (furnaceoutlet) is connected via a tube to the injector tube of theICP-torch. T
12、he graphite tube furnace is heated rapidly to atemperature where evaporation of analyte elements takes place.For complete volatilization of analyte elements, a halogenatingreaction gas is added to the argon carrier gas stream. Theevaporation products containing the analyte elements aretransported as
13、 dry aerosol with the argon carrier gas streamfrom the furnace outlet to the ICP-torch where they are excitedto emit optical radiation. The emitted radiation is dispersed anddetected by a simultaneous spectrometer. The intensity ofradiation of emission lines and background (optional) is1This test me
14、thod is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.F0 on Manufactured Carbon and Graphite Products.Current edition approved Oct. 1, 2018. Published December 2018. DOI:10.1520/D8186-18.2For refere
15、nced 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 American National Standards Institute (ANSI), 25 W. 43rd
16、 St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in
17、 the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1measured with appropriate detectors. The mass fractions of theanalyte elements are calculated by comparing the int
18、ensities ofthe element-specific spectral lines of the sample with calibra-tion samples of known analyte content.4.2 For ICP OES, sample introduction is usually done bynebulization of liquids. In the case of graphite, sample decom-position prior to analysis is required, for example, by ashing,melt-fu
19、sion, or acid/pressure-decomposition. These decompo-sition procedures are time-consuming, and the possibility ofintroduction of impurities as well as analyte losses represents aserious source of systematic errors. In ETV-ICP OES, sampleintroduction by nebulization of liquids is replaced by theelectr
20、othermal vaporization of solid samples at high tempera-tures in a graphite tube furnace, thus eliminating the need forwet chemical sample decomposition prior to analysis. Ingeneral, ETV-ICP OES provides a linear working range of upto four orders of magnitude.This range can be expanded for therespect
21、ive elements by selecting emission lines with differentsensitivity or variation of sample mass, or both.4.3 Aprerequisite for ETV-ICP OES is an efficient transportof the gaseous products generated in the graphite tube furnaceduring the heating step to the ICP-torch. This is achieved by asuitable gra
22、phite tube design and gas regime in the transitionarea between the graphite tube and transport tube as shown inFigs. 1 and 2. See also Refs (1-4).4Anozzle-type graphite tubeand the use of a bypass-gas in the gap between the graphitetube and transport tube are the key factors for high andreproducible
23、 transport efficiencies as well as minimized matrixeffects. The temperature of the graphite tube furnace in theevaporation step depends on the analytes to be determined.Release of volatile analytes (such as arsenic, cadmium,potassium, lithium, and sodium) from the graphite matrix startsat 500 C to 8
24、00 C. To measure all elements listed in 1.1 atemperature of 2600 C is required.4.4 By addition of a halogen-containing reaction gas to thecarrier gas, the vaporization temperatures of elements arelowered through the formation of volatile halides. In the caseof carbide-forming elements, halogenation
25、is a prerequisite tovaporize these elements. In addition, aerosols formed bypyrolysis of the reaction gas act as condensation nuclei forsample vapors, which have a positive effect on transportefficiency (see Refs (1-3), (5-7).To measure all elements listedin 1.1, dichlorodifluoromethane (CCl2F2) sha
26、ll be used asreaction gas. Using other reaction gases (for example, CF4,CCl2F2, CHF3, CHClF2,C2H2F4,SF6, and NF3) may result inreduced release of some analytes from the graphite matrix.4.5 The dry aerosol is transported by means of suitabletubing to the injector tube of the plasma torch of the ICPsp
27、ectrometer where it is excited to emit optical radiation (seeFig. 3).4.6 A description of possible interferences and their elimi-nation is given in Appendix X2.5. Significance and Use5.1 The presence and content of various impurities ingraphite are major considerations in determining the suitability
28、of graphite for various applications. This test method providesan alternative means of determining the content of traceimpurities in a graphite sample which has considerable advan-tages compared to classical wet-chemical analysis methods.5.2 The test method provides a standard procedure tomeasure im
29、purities in graphite and to assure required graphitespecifications.6. Apparatus6.1 Laboratory instruments are required as detailed in 6.2 to6.8. In the case of the spectrometer (6.2) and the ETV system(6.3), the user shall follow the manufacturers instructions onuse of the apparatus.6.2 Inductively
30、Coupled Plasma Optical EmissionSpectrometerA simultaneous method capable of recordingtransient emission signals, suited to synchronize data acquisi-tion with an ETV heating cycle.NOTE 1In ETV-ICP OES, the evaporating sample may cause asignificant alteration to the spectral background near the emissi
31、on lines,which increases the measurement uncertainty. This effect can be reducedif the spectrometer is capable of measuring the intensity of emission linesand the intensity of spectral background close to the emission lines4The boldface numbers in parentheses refer to the list of references at the e
32、nd ofthis standard.FIG. 1 ETV Unit: Schematic Design of Gas FlowsKey:1 Graphite tube with graphite boat and sample2 Transition area between graphite tube and transport tube3 Transport tube4 Carrier gas (argon)5 Reaction gas (CCl2F2)6 Furnace shield gas (argon)7 Bypass gas (argon)8 Dry aerosol to inj
33、ector tube of plasma torchD8186 182simultaneously. For method development, it is beneficial if the spectrom-eter is capable of recording emission signal intensities versus time(so-called “time-scan”).6.3 Electrothermal Vaporization SystemWith an electri-cally heated graphite tube furnace, graphite b
34、oats, reproduciblesetting and continuous control of temperatures up to 2600 C(tolerance 650 C), programmable temperature versus timeruns, controlled gas flows (preferably mass-flow controlled),graphite tube design and transition area between graphite tubeand transport tube optimized in terms of dry
35、aerosol formationand high transport efficiency, heat resistant tubing (up to150 C) to connect the ETV system with the ICP-torch,interface for synchronizing the ETV system with the ICPspectrometer.NOTE 2Reproducibility of analysis results can be improved using anautomated handling system for the grap
36、hite boats (autosampler). Anautosampler also increases sample throughput and saves working time.6.4 BalanceCapable of weighing to the nearest 0.01 mg.6.5 Tweezers.FIG. 2 ETV Unit: Schematic Design of Graphite Tube and Transition AreaKey:1 Graphite tube2 Transition area3 Nozzle of graphite tube4 Tran
37、sition tube (alumina)5 Carrier gas (argon)6 Reaction gas (CCl2F2)7 Bypass gas (argon)8 Gas-mixture and dry sample aerosol to injector tube of plasma torchFIG. 3 Schematic Design of ETV Unit and Coupling to ICPKey:1 Graphite tube furnace2 Graphite tube with graphite boat3 Graphite contacts4 Transitio
38、n area5 Furnace inlet with movable door6 Pyrometer for online temperature measurement7 Electrical power supply8 Carrier gas (argon) and reaction gas (CCl2F2)9 Furnace shield gas (argon)10 Bypass gas (argon)11 Transition tube (alumina)12 Tubing to injector tube of ICP torch13 Injector tube of ICP tor
39、ch14 ICP torchD8186 1836.6 Microspatula.6.7 Crusher or MillMaterial adapted to the analyticaltask.6.8 Drying ApparatusSuitable for contamination-free dry-ing of calibration solutions pipetted into the graphite boats, adrying temperature of maximum 100 C, and heating ofgraphite boats from both sides.
40、6.8.1 Ensure that possible contamination originating fromlaboratory instruments has no effect on the accuracy of theanalysis results.7. Reagents and Materials7.1 Purity of ReagentsReagents of known analytical gradeshall be used, provided it is first ascertained that the reagent isof sufficiently hig
41、h purity to permit its use without compro-mising the accuracy of the determination.7.2 Sample BoatsMade out of low-porosity orpyrolytically-coated high-purity graphite, the size adapted tothe graphite tube of the ETV-furnace.NOTE 3With low-porosity or pyrolytically-coated graphite sampleboats, diffu
42、sion of calibration solution through the sample boat can beavoided.7.3 Reaction GasDichlorodifluoromethane (CCl2F2).NOTE 4The use of ozone-depleting substances such as CCl2F2isrestricted under the Clean Air Act. For laboratory and research purposes,however, the use of CCl2F2is still allowed. Complet
43、e thermal decompo-sition of CCl2F2is achieved in the hot graphite tube furnace and in theinductively-coupled plasma.7.4 WaterComply with grade II of ASTM SpecificationD1193.7.5 Calibration SolutionsAqueous single- or multi-element calibration solutions, prepared by dilution of commer-cially availabl
44、e standard-stock solutions with water to therequired concentration.7.6 Calibration SamplesWith defined mass fractions ofimpurities, preferably certified reference materials (CRM).NOTE 5A commercially available CRM is listed in Appendix X3.7.7 ArgonPurity 99.996 (volume fraction).8. Sampling and Samp
45、le Preparation8.1 Sampling shall be representative of the graphite gradelots and billets. If the dry state of the graphite is not secured,the sample must be dried at 110 C 6 5 C until there is nochange in mass and then stored in a desiccator. Inhomogeneoussample materials must be homogenized.8.2 Gra
46、phite blocks shall be crushed or sawed into smallpieces which fit into the graphite boats or milled to graphitepowder. Alternatively, a powder sample may be drilled out ofthe graphite block (graphite foil and graphite felt shall beripped into small pieces, for example, using tweezers, which fitinto
47、the graphite boats). Standard apparatus and procedures forsample preparation may be used provided that no contamina-tion occurs which affects the accuracy of the determination.Special attention should be paid to contamination control ifhigh-purity graphite materials are analyzed.9. Preparation of Ap
48、paratus9.1 ICP OESConsult the manufacturers instructions forthe operation of the inductively coupled plasma optical emis-sion spectrometer.9.2 ETV SystemConsult the manufacturers instructionsfor the operation of the electrothermal vaporization system.Before use, the graphite boats must be cleaned by
49、 thermo-halogenation in the graphite tube furnace of the ETV system ata temperature not lower than the vaporization temperature usedfor sample analysis.9.3 Operating Parameters for ICP OES and ETV SystemFor materials other than graphite, these parameters must beevaluated as part of method development for each specificmaterial.Appropriate operating parameters shall be establishedusing calibration samples, preferably certified reference mate-rials. The release behavior of each analyte shall be investigatedby recording the intensity of the used
