1、Designation: F 2617 08Standard Test Method forIdentification and Quantification of Chromium, Bromine,Cadmium, Mercury, and Lead in Polymeric Material UsingEnergy Dispersive X-ray Spectrometry1This standard is issued under the fixed designation F 2617; the number immediately following the designation
2、 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 describes an energy
3、dispersive X-rayfluorescence (EDXRF) spectrometric procedure for identifica-tion and quantification of chromium, bromine, cadmium,mercury, and lead in polymeric materials.1.2 This test method is not applicable to determine totalconcentrations of polybrominated biphenyls (PBB), polybro-minated diphen
4、yl ethers (PBDE) or hexavalent chromium. Thistest method cannot be used to determine the valence states ofatoms or ions.1.3 This test method is applicable for a range from 20 mg/kgto approximately 1 wt % for chromium, bromine, cadmium,mercury, and lead in polymeric materials.1.4 This test method is
5、applicable for homogeneous poly-meric material.1.5 The values stated in SI units are to be regarded as thestandard. Values given in parentheses are for information only.1.6 This test method is not applicable to quantitative deter-minations for specimens with one or more surface coatingspresent on th
6、e analyzed surface; however, qualitative informa-tion may be obtained. In addition, specimens less than infi-nitely thick for the measured X rays, must not be coated on thereverse side or mounted on a substrate.1.7 This standard does not purport to address all of thesafety concerns, if any, associat
7、ed 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 883 Terminology Relating to PlasticsD 3641 Practice for Inj
8、ection Molding Test Specimens ofThermoplastic Molding and Extrusion MaterialsD 4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens, Plaques, or SheetsD 6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasureme
9、nt System PerformanceE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE 1361 Guide for Correction of Interelement Effects inX-Ray Spectrometric AnalysisF 2576 Ter
10、minology Relating to Declarable Substances inMaterials3. Terminology3.1 DefinitionsDefinitions of terms applying to XRF, plas-tics and declarable substances appear in Terminology E 135,Terminology D 883 and Terminology F 2576, respectively.3.1.1 Compton scatterthe inelastic scattering of an X-raypho
11、ton through its interaction with the bound electrons of anatom; this process is also referred to as incoherent scatter.3.1.2 Rayleigh scatterthe elastic scattering of an X-rayphoton through its interaction with the bound electrons of anatom; this process is also referred to as coherent scatter.3.1.2
12、.1 DiscussionThe measured count rate of Comptonand Rayleigh scattered radiation varies depending upon speci-men composition and may thus be used to compensate formatrix effects. One option is to use the measured count rate ofthe Compton scatter in the same manner as the measured countrate of an inte
13、rnal standard element. Alternatively, the mea-sured count rate of the Compton scatter or the Compton/Rayleigh scatter ratio may be used indirectly for estimating theeffective mass absorption coefficient of the specimen, which isused to compensate for matrix effects. The concept of correc-tions based
14、 on the Compton scatter effect is discussed as anoptional part of several calibration choices in this standard.1This test method is under the jurisdiction of ASTM Committee F40 onDeclarable Substances in Materials and is the direct responsibility of SubcommitteeF40.01 on Test Methods.Current edition
15、 approved Aug. 15, 2008. Published September 2008.2For 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.1Copyright
16、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.3 fundamental parameters (FP) modela model forcalibration of X-ray fluorescence response, including the cor-rection of matrix effects, based on the theory describing thephysical processes of t
17、he interactions of X rays with matter.3.1.4 homogeneous polymeric materialpolymeric mate-rial is considered homogeneous for XRF when the elementalcomposition is independent with respect to the measuredlocation on the specimen and among separate specimensprepared from the same polymeric material.3.1.
18、5 infinite thickness (or critical thickness)the thicknessof specimen which, if increased, yields no increase in intensityof secondary X rays, due to absorption by the polymer matrix.This thickness varies with secondary X-ray energy, or wave-length.3.2 Abbreviations:3.2.1 EDXRFenergy dispersive X-ray
19、 fluorescence3.2.2 FPfundamental parameters3.2.3 PBBpolybrominated biphenyl3.2.4 PBDEpolybrominated diphenyl ether4. Summary of Test Method4.1 The optimum test sample is a smooth plaque or disklarge enough to cover the viewed area of the spectrometer.Suitable specimens may be die-cut from extruded s
20、heets, ormolded from resin pellets, from powders or from granules.4.2 The specimen is placed in the X-ray beam, and theappropriate region of its spectrum is measured to give the countrates or fluorescent intensities of lead, mercury, cadmium,chromium and bromine.4.3 The EDXRF spectrometer is calibra
21、ted by one of severalapproaches including fundamental parameters and empirical,classical curve construction, with either empirical or theoreti-cal influence coefficients, from measured polymer referencematerials. The calibration may be performed by the manufac-turer or by the user.4.4 Choices of app
22、ropriate characteristic X-ray lines andspectrometer test conditions may vary according to eachelement and with factors such as detector response, concentra-tion range and other elements present in the polymer matrix.5. Significance and Use5.1 This test method is intended for the determination ofchro
23、mium, bromine, cadmium, mercury, and lead, in homoge-neous polymeric materials. The test method may be used toascertain the conformance of the product under test to manu-facturing specifications. Typical time for a measurement is 5 to10 min per specimen, depending on the specimen matrix andthe capab
24、ilities of the EDXRF spectrometer.6. Interferences6.1 Spectral InterferencesSpectral interferences resultfrom the behavior of the detector subsystem of the spectrom-eter and from scattering of X rays by the specimen, by asecondary target or by a monochromator, if the spectrometer isso equipped. Over
25、laps among the X-ray lines from elements inthe specimen are caused by the limited resolution of thedetection subsystem. Depending upon the resolution of thedetector system, the peaks from Zn, Br, Hg and Pb may overlapwith one another. Peaks from Cd may overlap with peaks fromCa, Sn, or other element
26、s. Interactions of photons and electronsinside the detector give rise to additional peaks in a spectrumknown as escape peaks and sum peaks. Fundamental Param-eters equations require that the measured net count rates be freefrom line overlap effects. Some empirical approaches incorpo-rate line overla
27、p corrections in their equations. Manufacturerssoftware may provide tools to compensate for overlappedpeaks, escape peaks, and sum peaks in spectra. The degree ofline overlap and the best method to account or correct for itmust be ascertained on an individual basis and must beconsidered when calibra
28、ting the instrument.6.2 Interelement EffectsInterelement effects, also calledmatrix effects, exist among all elements as the result ofabsorption of fluorescent X rays (secondary X rays) by atomsin the specimen. Absorption reduces the apparent sensitivityfor the element. In contrast, the atom that ab
29、sorbs the X raysmay in turn emit a fluorescent X ray, increasing the apparentsensitivity for the second element. Mathematical methods maybe used to compensate for matrix effects. A number ofmathematical correction procedures are commonly utilizedincluding full FPtreatments and mathematical models ba
30、sed oninfluence coefficient algorithms. The influence coefficients maybe calculated either from first principles or from the empiricaldata, or some combination of the two approaches. See GuideE 1361 for examples of these approaches. Also, consult thesoftware manual for the spectrometer for informati
31、on on theapproaches provided with the spectrometer. Any of these thatwill achieve the necessary analytical accuracy is acceptable.Examples of common interelement effects are listed in Table 1.7. Apparatus7.1 EDXRF SpectrometerDesigned for X-ray fluores-cence analysis with energy dispersive selection
32、 of radiation.The spectrometer is equipped with specimen holders and aspecimen chamber. Any EDXRF spectrometer may be used ifits design incorporates the following features.TABLE 1 Common Interelement Effects in Formulated PlasticsCause EffectAbsorption by Cl in PVC Reduced sensitivity for all analyt
33、es ascompared to when they are occurringat the same concentration level inpolyolefinsPolymers of similar composition butdifferences in the relativeconcentrations of H and CDifferences in C/H among calibrantsand samples may result in biases of afew percent (relative).Unmeasured elements B, N, O, and
34、Fpresent in the matrix of the polymer,for example, amide, fluorinated, andterephthalate compounds.If concentrations differ from thecalibrants, substantial concentrationsof these elements may causesignificant changes in both apparentsensitivity and background count rates.Absorption by elements presen
35、t inflame-retardant compounds such asPBBs, PBDEs, and Sb2O3Reduction of apparent sensitivity formost analytesAbsorption by Na, P, S, Ca, Ti, Zn,Mo, Sn, Ba, and other elementsincluded in a formulation as fillers orperformance additivesReduction of apparent sensitivity formost analytesF26170827.1.1 So
36、urce of X-ray Excitation, capable of exciting therecommended lines listed in Table 2, typically an X-ray tube.7.1.2 X-ray Detector, with sufficient energy resolution toresolve the recommended lines listed in Table 2. An energyresolution of better than 250 eV at Mn K-L2,3(Ka) has beenfound suitable.7
37、.1.3 Signal Conditioning and Data Handling Electronicsthat include the functions of X-ray counting and peak process-ing.7.2 The following spectrometer features and accessories areoptional:7.2.1 Beam FiltersUsed to make the excitation moreselective and reduce background count rates.7.2.2 Secondary Ta
38、rgetsUsed to produce semi-monochromatic radiation enhancing sensitivity for selectedX-ray lines and to reduce spectral background for improveddetection limits. The use of monochromatic radiation alsoallows the simplification of FP calculations.7.2.3 Specimen SpinnerUsed to reduce the effect of sur-f
39、ace irregularities of the specimen.7.2.4 Vacuum PumpFor improved sensitivity of atomicnumbers 20 (Ca) or lower, the X-ray optical path may beevacuated using a mechanical pump.7.2.5 Helium FlushFor improved sensitivity of atomicnumbers 20 (Ca) or lower, the X-ray optical path may beflushed with heliu
40、m.7.3 Drift Correction Monitor(s)Due to instability of themeasurement system, the sensitivity and background of thespectrometer may drift with time. Drift correction monitorsmay be used to correct for this drift. The optimum driftcorrection monitor specimens are permanent materials that arestable wi
41、th time and repeated exposure to X rays Note 1.NOTE 1Suitable drift correction monitors may be fused bead speci-mens containing the relevant elements (Cr, Br, Cd, Hg, and Pb) orelements that have fluorescence with the same energies as the elements ofinterest.8. Reagents and Materials8.1 Purity of Re
42、agents3Reagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society (ACS)where such specifications are available. Other grades may beused provided i
43、t is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination. Reagents used include allmaterials used for the preparation of reference materials andfor cleaning of specimens.8.2 Reagents:8.2.1 Isopropanol or ethanol.8.2.2
44、Nitric acid (HNO3).8.2.3 Hexane.8.2.4 Deionized water (H2O).8.3 GlovesDisposable cotton gloves are recommended forhandling reference materials and other specimens to minimizecontamination.8.4 Appropriate personal protective equipment for the han-dling of reagents.8.5 Reference Materials:8.5.1 Polyme
45、r reference materials are available from bothmetrology institutes and commercial sources. Some are pro-vided in disk form, and some are available as granules orextruded pellets.8.5.2 Reference materials may be prepared by addingknown amounts of pure compounds or additives (or both), toan appropriate
46、 polymeric base material. It is recommended tomake reference materials using the same base polymer as theunknown samples.8.5.2.1 Thorough mixing of ingredients is required foroptimum homogeneity. Options may include grinding, melt-blending, repeated extrusion, and solvent dissolution.8.5.2.2 Element
47、al concentrations may be calculated fromthe concentrations and molecular formulae of the compoundsand additives used.8.5.2.3 The elemental compositions of user-prepared refer-ence materials must be confirmed by one or more independentanalytical methods.8.6 Quality Control Samples:8.6.1 To ensure the
48、 quality of the results, analyze qualitycontrol (QC) samples at the beginning and at the end of eachbatch of specimens or after a fixed number of specimens, but atleast once each day of operation. If possible, the QC sampleshall be representative of samples typically analyzed. Thematerial shall be h
49、omogeneous and stable under the anticipatedstorage conditions. An ample supply of QC sample materialshall be available for the intended period of use.9. Hazards9.1 Occupational Health and Safety standards for X raysand ionizing radiation shall be observed. It is also recom-mended that proper practices be followed as presented by mostmanufacturers documentation. Guidelines for safe operatingprocedures are also given in current handbooks and publica-tions from original equipment manufacturers. For more infor-mation see similar handbooks on radiation safety.9.2
