1、Designation: D 6357 04Standard Test Methods forDetermination of Trace Elements in Coal, Coke, andCombustion Residues from Coal Utilization Processes byInductively Coupled Plasma Atomic Emission Spectrometry,Inductively Coupled Plasma Mass Spectrometry, andGraphite Furnace Atomic Absorption Spectrome
2、try1This standard is issued under the fixed designation D 6357; 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 (e) indi
3、cates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods pertain to the determination ofantimony, arsenic, beryllium, cadmium, chromium, cobalt,copper, lead, manganese, molybdenum, nickel, vanadium, andzinc in coal and coke. These test methods can also be used f
4、orthe analysis of residues from coal combustion processes.NOTE 1These test methods may be applicable to the determination ofother trace elements.1.2 The values stated in SI units shall be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associa
5、ted 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:2D 121 Terminology of Coal and CokeD 346 Practice for Collect
6、ion and Preparation of CokeSamples for Laboratory AnalysisD 1193 Specification for Reagent WaterD 2013 Practice of Preparing Coal Samples for AnalysisD 3173 Test Method for Moisture in the Analysis Sample ofCoal and CokeD 3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Diff
7、erent BasesD 4621 Guide for Quality Management in an OrganizationThat Samples or Tests Coal and CokeD 5142 Test Methods for Proximate Analysis of the Analy-sis Sample of Coal and Coke by Instrumental ProceduresE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test
8、 Method2.2 Other Documents:EPA/600/4-91/010 Methods for the Determination of Met-als in Environmental Samples33. Terminology3.1 DefinitionsDefinitions applicable to these test meth-ods are listed in Terminology D 121.4. Summary of Test Method4.1 The coal or coke to be analyzed is ashed under con-tro
9、lled conditions, digested by a mixture of aqua-regia andhydrofluoric acid, and finally dissolved in 1 % nitric acid.Combustion residues are digested on an as-received basis. Theconcentration of individual trace elements is determined byeither inductively coupled atomic emission spectrometry (IC-PAES
10、) or inductively coupled plasma mass spectrometry(ICPMS). Selected elements that occur at concentrations belowthe detection limits of ICPAES can be quantitatively analyzedby graphite furnace atomic absorption spectrometry (GFAA).5. Significance and Use5.1 Coal contains several elements whose individ
11、ual con-centrations are generally less than 0.01 %. These elements arecommonly and collectively referred to as trace elements. Theseelements primarily occur as part of the mineral matter in coal.The potential release of certain trace elements from coalcombustion sources has become an environmental c
12、oncern.5.2 The ash prepared in accordance with these provisionaltest methods quantitatively retains the elements listed in 1.1and is representative of their concentrations in the coal or coke.1These test methods are under the jurisdiction of ASTM Committee D05 on Coaland Coke and are the direct resp
13、onsibility of Subcommittee D05.29 on MajorElements in Ash and Trace Elements of Coal.Current edition approved Oct. 1, 2004. Published November 2004. Originallypublished in 1996. Last previous edition approved in 2000 as D 6357 - 00a.2For referenced ASTM standards, visit the ASTM website, www.astm.or
14、g, 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 Superintendent of Documents, U.S. Printing Office, Washing-ton, DC 20402.1Copyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Inductively Coupled Plasma Atomic Emission Spectrom-eter (ICPAES)The spectrometer system may be either simul-taneous or sequential, vacuum or purged, but must includecomputer-controlled background correction.
16、6.1.1 Argon Gas SupplyHigh purity (99.99 %).6.1.2 Mass Flow ControllersA mass-flow controller toregulate the nebulizer gas is required. Mass flow controllers onthe intermediate and outer torch gas flows are recommended.6.2 Inductively Coupled Plasma Mass Spectrometer(ICPMS)The spectrometer system mu
17、st be capable of scan-ning the mass range of the elements to be analyzed.6.2.1 Argon Gas Supply, high purity (99.99 %).6.2.2 The use of a variable speed peristaltic pump fordelivering sample solution to the nebulizer, a mass-flowcontroller on the gas supply to the nebulizer, and a water-cooled spray
18、 chamber are highly recommended.6.3 Atomic Absorption Spectrometer with Graphite Furnace(GFAA), having background correction capable of removingnonspecific absorbance.6.3.1 Single-Element Hollow Cathode or Single-ElementElectrodeless Discharge Lamps.6.3.2 Single-Output Device, capable of recording a
19、nd evalu-ating peak area and peak shape.6.3.3 Pyrolytic Coated Graphite Tubes and Platforms.6.3.4 Argon Gas Supply, high purity (99.99 %).6.3.5 AutosamplerAlthough not specifically required, theuse of an autosampler is highly recommended.6.4 Muffle Furnace, with temperature control and with aircircu
20、lation as specified in 9.1.6.5 Analytical Balance, capable of weighing to 0.1 mg.6.6 Teflon Beakers, 100- or 200-mL capacity.6.7 Hot Plate, capable of regulating temperature between 90to 150C.6.8 Volumetric Flasks, 100- and 10-mL capacity.6.9 HDPE Bottles, 100-mL capacity.6.10 Crucibles, 50-mL quart
21、z or high silica.7. Reagents7.1 Purity of ReagentsAll acids used in these test methodsmust be trace metal purity grade or equivalent. Redistilledacids are acceptable.7.2 Purity of WaterThe purity of the water used in thesetest methods shall be equivalent to ASTM Type II reagentwater of Specification
22、 D 1193.7.3 Aqua Regia SolutionMix one part concentrated nitricacid (HNO3, sp. gr. 1.42) and three parts concentrated hydro-chloric acid (HCl, sp. gr. 1.9).7.4 Hydrofluoric AcidConcentrated (HF, sp. gr. 1.15).7.5 ICP Calibration StandardsAqueous multielement so-lutions made up in 1 % HNO3are used fo
23、r calibration ofICPAES and ICPMS systems. The standards may be purchasedor prepared from high-purity grade chemicals or metals.7.5.1 GFAA Stock Standard Solution (1000 ppm)Single-element standards either purchased or prepared from high-purity grade chemicals or metals.7.5.2 GFAA Intermediate Stock S
24、tandard Solution (1ppm)Add 0.1 mL of stock standard solution (7.5.1) and 1 mLof concentrated nitric acid to a 100-mL volumetric flask. Diluteto volume with water.7.6 Magnesium Nitrate SolutionMatrix modifier (seeNote 2), (106g/L Mg(NO3)26H2O) for the determination ofarsenic and antimony, equivalent
25、to 10 000-ppm magnesium.NOTE 2A matrix modifier is used to minimize GFAA interferenceeffects by selective volatilization of either the analyte or the matrixcomponents. Other matrix modifiers such as nickel nitrate or palladiumnitrate can be used. The analyst should compare modifiers to establishopti
26、mum performance as outlined in 10.1.7.7 Blank SolutionsAll of the test methods in this stan-dard require two types of blank solutions. A calibration blankthat is used to establish the analytical calibration curve and amethod blank which is used to evaluate possible contaminationand assess spectral b
27、ackground.7.7.1 Calibration BlankA 1 % nitric acid solution. Whenusing matrix modifiers of GFAA, the calibration blank shallalso contain the same equivalent concentration.7.7.2 Method BlankConsists of all the reagents in thesame volumes as used in preparing the samples. The methodblank shall be proc
28、essed through the entire sample digestionscheme.8. Analysis Sample8.1 Samples of coal and coke shall be prepared in accor-dance with Practice D 2013 or Practice D 346.8.2 Standard practices for the sampling and preparation ofresidues from coal utilization processes have not been estab-lished. Some o
29、f these materials are highly abrasive. The use ofhigh speed pulverizers for size reduction shall be avoided. Theuse of jaw crushers followed by final preparation in an agatemortar and pestle is recommended to prevent contamination ofthe sample.8.3 Analyze separate test portions for moisture content
30、inaccordance with Test Methods D 3173 and D 5142 so thatcalculations to other bases can be made.9. Procedure9.1 AshingWeigh to the nearest 0.1 mg enough of the coalor coke sample that will yield approximately 0.5 g of ash intoan open 50-mL quartz or high-silica crucible. Place the cruciblein a cold
31、muffle furnace. Adjust the temperature control so thatthe furnace reaches a temperature of 300C in 1 h and then500C in the second hour. Maintain the furnace temperature at500C for a minimum of 2 h, stirring the sample occasionally.Ashing is complete when no visible evidence of carbonaceousmaterial r
32、emains. Cool the samples to room temperature underconditions that minimize the absorption of water. Grind the ashto pass a 150-m (No. 100) U.S.A. standard sieve in an agatemortar then reignite at 500C for 1 h. Cool the ash and store ina desiccator. Determine the percentage of ash by analyzingunder t
33、he same conditions a separate portion of the analysissample.NOTE 3If all the ash from 9.1 is quantitatively transferred fordigestion in 9.2, it is not necessary to sieve and grind the ash. Results from11.2.3, 12.3, or 13.1.3.8 are then ppm of the element in the as-determinedsample.D63570429.2 Dissol
34、utionWeigh 0.2000 to 0.5000 g of the thor-oughly blended ash prepared according to 9.1 into a 100- or200-mL Teflon beaker. Add 20 mL of aqua regia and 20 mL ofconcentrated hydrofluoric acid to the beaker. Place the beakeron a hot plate that has been adjusted to 130 to 150C. Heat themixture to drynes
35、s, but do not bake. After the solution hasevaporated, rinse the beaker walls with deionized water andheat this solution to dryness, again being careful not to bake thesample. Remove the beaker from the hot plate and cool to roomtemperature. Add 1 mL of concentrated nitric acid and 20 mLof deionized
36、water to the beaker. Heat the contents on a hotplate at 90 to 100C until the sample is in solution. If a residueremains after1hofheating, it may be ignored. The traceelements are considered to be quantitatively extracted at thispoint. Remove the beaker from the hot plate and allow thesolution to coo
37、l to room temperature. Transfer the cool solutionto a 100-mL volumetric flask and dilute to volume withdeionized water. If the solution is not to be analyzed immedi-ately, transfer to a HDPE bottle to avoid adsorption of leadduring storage. Prepare a method blank (7.7.2) with each batchof samples to
38、 be analyzed.NOTE 4To minimize contamination, clean laboratory ware in a 1:1solution of HNO3followed by a 1:1 solution of HCl then rinse thoroughlywith deionized water.10. Analysis10.1 Because of the differences between various makes andmodels of instruments, all instrumental operating instructionsc
39、annot be provided. Instead, the analyst shall refer to theinstructions provided by the manufacturer of the particularinstrument. Sensitivity, instrumental detection limit, lineardynamic range, interference effects, and appropriate back-ground correction shall be investigated and established for each
40、individual analyte on that particular instrument.11. Test Method AInductively Coupled Plasma AtomicEmission Spectroscopy11.1 Table 1 shows the elements listed in 1.1 along withsome suggested wavelengths for inductively coupled plasmaatomic emission spectrometry (ICPAES). Other wavelengthsmay be subs
41、tituted if they can provide the needed sensitivityand are treated according to the provisions of 10.1. Also shownare estimated detection limits.11.2 Calibration ProcedureCalibrate the instrument ac-cording to the procedure recommended by the manufacturerusing a calibration blank and aqueous multiele
42、ment standardsmade up in 1 % trace metal grade HNO3. All calibrationsolutions must also contain an internal standard (see Note 5).Records for all calibrations must be in accordance with GuideD 4621.NOTE 5An internal standard is needed to compensate for:1. Differences in physical properties (such as
43、viscosity) between thecalibration standard and the test samples and2. Drift caused by thermal changes in the laboratory which will affectthe instrument optics.An appropriate internal standard element should:(i) not be naturally present in the test samples in appreciable concen-trations,(ii) not pres
44、ent spectral interferences with any analyte,(iii) be a strong emitter so that its relative concentration can be keptlow, and(iv) be as chemically similar to the analyte as possible.11.2.1 Initial Calibration VerificationBefore analyzingtest samples, analyze the method blank and verify the propercali
45、bration of the instrument by analyzing a reference materialthat has traceability to an internationally recognized certifyingagency such as NIST. Results for the reference material mustbe within the stated uncertainty limits or the calibrationprocedure must be repeated.11.2.2 Periodic Calibration Ver
46、ification andRecalibrationIn accordance with Guide D 4621, analyze acontrol sample such as NIST on a periodic basis. Resultsobtained for the control sample must be within 10 % of thestated value or all results obtained since the last successfulcontrol check of that element must be rejected and theca
47、libration procedure repeated.11.2.3 CalculationCalculate the concentration of the ele-ment in the ash as follows:C 5 A 3 df!/W 3 100! (1)where:C = weight percent of the element in the ash,df = dilution factor,A = ppm of the element in solution, andW = weight of the sample in grams.12. Test Method BI
48、nductively Coupled Plasma MassSpectrometry12.1 Table 2 shows the elements listed in 1.1, the isotope,and its abundance used for ICPMS determinations. Also shownare some potential molecular interferents.12.2 CalibrationIn conjunction with 11.2, calibrate theinstrument by analyzing a blank consisting
49、of deionized waterand appropriate internal standards (see Note 6), and a 1 %solution of HNO3containing 0 ppb of the elements to beTABLE 1 Suggested Wavelengths for ICPAESElementWavelength,nmEstimatedDetectionLimit,g/LAAsB189.042, 228.812, 193.759 53Be 313.042 0.3CdB226.502 4Co 228.616 7Cr 267.716, 205.552 7Cu 324.754 6Mn 257.610 30Mo 202.030, 203.844 8Ni 231.604 15Pb 220.353 42SbB217.581, 206.833 32V 292.402, 292.464 8Zn 213.856 2ADetection limits are given for informational purposes only and represent thelowest concentration that produces a in
