ASTM D8207-2018 1875 Standard Test Method for Determination of Metals in Purified Terephthalic Acid (PAT) by Atomic Absorption (AA) Spectrometry.pdf

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1、Designation: D8207 18Standard Test Method forDetermination of Metals in Purified Terephthalic Acid (PAT)by Atomic Absorption (AA) Spectrometry1This standard is issued under the fixed designation D8207; the number immediately following the designation indicates the year oforiginal adoption or, in the

2、 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 aluminum,chromium, cobalt, titanium, iron,

3、 manganese, molybdenum,sodium and nickel in purified terephthalic acid (PAT) bygraphite furnace atomic absorption (GFAA) spectrometry. It isapplicable to PAT samples containing sodium, chromium,cobalt, titanium, manganese, molybdenum and nickel over0.004 mg/kg, and iron and aluminum over 0.054 mg/kg

4、.1.2 In determining the conformance of the test results usingthis method to applicable specification, results shall be roundedoff in accordance with the rounding-off method of PracticeE29.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in t

5、hisstandard.1.4 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, health, and environmental practices and deter-mine the applicability of regulatory limitations

6、prior to use.Some specific hazards statements are given in 6.3, 6.10, 6.11,Section , and 9.1.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Stand

7、ards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quali

8、ty AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE300 Practice for Sampling Industrial ChemicalsE691 Practi

9、ce for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1184 Practice for Determination of Elements by GraphiteFurnace Atomic Absorption Spectrometry2.2 Other Document:3OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.12003. Summary of Test Method3.1 PAT sample in

10、a platinum crucible is ignited and burned,then ashed at 750C approximately for 45 min in a mufflefurnace, and finally dissolved with sulfuric acid solution. Thesample solution is analyzed by graphite furnace atomic absorp-tion spectrophotometer. The external standard calibration isused for quantific

11、ation.4. Significance and Use4.1 The presence of metals in PAT used for the productionof polyester is undesirable because they may speed up or slowdown the reaction and be impurities in the final product.4.2 Determination of metals in PAT is often required. Thistest method is suitable for setting sp

12、ecifications and for use asan internal quality control tool where these products areproduced or used.5. Apparatus5.1 Atomic Absorption Spectrometer with GraphiteFurnace, having background correction capable of removingnonspecific absorbance.1This test method is under the jurisdiction of ASTM Committ

13、ee D16 onAromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-bility of Subcommittee D16.02 on Oxygenated Aromatics.Current edition approved June 1, 2018. Published August 2018. DOI: 10.1520/D8207-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or

14、contact 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 U.S. Government Printing Office, Superintendent ofDocuments, 732 N. Capitol St., NW, Washington, DC 20401-0001, http:

15、/www.access.gpo.gov.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 the Decision on Principles for the

16、Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.2 Hollow Cathode Lamps.5.3 Autosampler or Manual Pipettor.5.4 Analytical Balance, readable to 60.0001 g.5.5 Muffle Furnace, with temperature contro

17、l as (750 625C).5.6 Platinum Crucible, with capacity of 60 to 100 mL andweight no more than 22 g.6. Reagents and Materials6.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the reagent gradespecification of the analytical reagents of theAmerican Chemi-

18、cal Society, where such specifications are available.4Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.NOTE 1Calibration and detection limits of this test method are biasedby

19、the purity of the reagents.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D1193, Type II. Other reagent water types maybe used, provided it is first ascertained that the water is ofsufficiently high purity to per

20、mit its use without lessening thebias and precision of the determination.6.3 Sulfuric AcidUltrapure, over 96 % (w/w). It may bepurchased. Metal impurities should be no more than 1 g/kg.(WarningPoison, danger, corrosive. Causes severe burns.Harmful or fatal if swallowed or inhaled.)6.4 Sulfuric Acid

21、SolutionA 1:1 (v/v) mixture of sulfuricacid (6.3) and water.6.5 Single Element Standard Solution (100 mg/L)Standards either purchased or prepared from high purity gradechemicals or metals in Table 1.6.6 Multi-element Standard Stock Solution (1.0 mg/L)Pipette 1.0 mL of each single element standard so

22、lution (6.5)into a 100 mL volumetric flask, mix and dilute to mark withwater (6.2).6.7 Mixed Working StandardsFreshly prepared by trans-ferring into twelve 100-mL volumetric flasks 0.00, 0.20, 0.40,0.60, 0.80, 1.00, 2.00, 4.00, 6.00, 8.00, 10.00, 12.00 mL of themulti-element standard stock solution

23、(6.6) and dilute withwater (6.2) to the mark to give 0.0, 2.0, 4.0, 6.0, 8.0, 10.0, 20.0,40.0, 60.0, 80.0, 100.0 and 120.0 g/ L working standards.NOTE 2The ranges of the calibration curves for both iron and nickelare suggested to be between 0 and 20 g/ L for being linear. And for otherelements, the

24、ranges are suggested to be between 0 and 120 g/ L.6.8 Sodium Standard Solution (0.1 mg/L)Pipette 0.1 mLof sodium single element sodium standard solution (6.5) into a100 mL volumetric flask, mix and dilute to mark with water(6.2).6.9 Sodium Working StandardsFreshly prepared by trans-ferring into six

25、100-mL volumetric flasks 0.00, 1.00, 2.00,3.00, 4.00, 5.00 mL of sodium standard solution (6.8). Dilutewith water (6.2) to the mark to give 0.0, 1.0, 2.0, 3.0, 4.0 and5.0 g/L sodium working standards. For best results, preparethese working standards daily and store in plastic bottles, or asrequired.

26、6.10 Argon Gas99.99 % minimum purity, (WarningArgon is a compressed gas under high pressure.) for graphitefurnace gas flow system.6.11 EthanolOver 99.8 % (w/w). Metal impurities shouldbe no more than 1 g/kg. (WarningEthanol is highlyflammable.)6.12 Filter PaperQuantitative grade.7. Hazards7.1 Consul

27、t current federal regulations, suppliers SafetyData Sheets, and local regulations for all materials used in thistest method.8. Sampling, Test Specimens, and Test Units8.1 Use only representative samples obtained as describedin Practice E300, unless otherwise specified.9. Preparation of Apparatus9.1

28、Consult the manufacturers instructions for the opera-tion of the graphite furnace atomic absorption spectrometer.The present test method assumes that good operating proce-dures are followed. Because of the differences in equipment, allinstrumental operating instructions cannot be provided.Instead, t

29、he analyst shall refer to the instructions provided bythe manufacturer of the particular instrument. Sensitivity,instrumental detection limit, linear dynamic range, interferenceeffects, and appropriate background correction shall be inves-tigated and established for each individual analyte on thatpa

30、rticular instrument. (WarningBeware of high voltage andhigh temperature conditions when using this instrument.)9.2 Recommended graphite furnace atomic absorption op-erating conditions are listed in Table 1.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washin

31、gton, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.TABLE 1 Rec

32、ommended Atomic Absorption SpectrometerWorking ConditionsElementWavelengthnmSlit WidthnmPyrolysisTemperatureCAtomizationTemperatureCAl 309.3 0.7 900 2600Cr 357.9 0.2 800 2300Co 240.7 0.2 400 2500Ti 364.3 0.2 900 2600Fe 248.3 0.2 800 2500Mn 279.5 0.2 1000 2200Mo 313.3 0.7 1000 2600Na 589.0 0.2 500 20

33、00Ni 232.0 0.2 800 2500D8207 18210. Calibration10.1 Initially set up the instrument in accordance withmanufacturers specifications. Pipette water on the platforminto the graphite furnace and zero the instrument. Then pipettethe working standards (6.7 and 6.9) sequentially and determinethe absorbance

34、 of each element. Pipette water (6.2) alone aftereach standard.10.2 Plot the absorbance against the concentration of eachelement in the standards to give a calibration curve.NOTE 3The calibration curve may be automatically calculated by theinstrument software and displayed by way of the instrument c

35、omputerterminal, making actual plotting unnecessary.10.3 Calibration must be carried out prior to each group ofsamples to be analyzed and after any change in instrumentalconditions, as variation occurs in the instrument behavior.Readings may also vary over short times from such causes asgraphite fur

36、nace stability and graphite pipe being damaged.Thus, a mixed standard should be analyzed from time to timeduring a series of samples to check whether the calibration haschanged.11. Analysis of Samples11.1 AshingWeigh accurately 50 g PAT sample into plati-num crucible, to the nearest 0.01 g. Add 1 to

37、 2 mL ethanol(6.11) to the surface of sample. Place the platinum crucible onthe electric stove, turn on the heat and increase the temperaturegently. Ignite the sample with filter paper (6.12) until the fumeis generated, and turn on fume cupboard switch afterwards.When several samples are ashed at th

38、e same time, the mutualinterference between samples should be avoided.11.2 After sample ashing process, place the platinum cru-cible in the muffle furnace which is set at 750C, gently closethe door and leave it for approximately 45 min until the sampleis burned to ash.11.3 Take out the platinum cruc

39、ible carefully, and cooldown. Dissolve the inorganic residue completely by adding 5mL sulfuric acid solution (6.4). Place the platinum crucibleback to the electric stove and heat the mixture to dryness.Gently shake the platinum crucible 23 times during heating.11.3.1 Add 1 mL sulfuric acid solution

40、(6.4) into theplatinum crucible, wash the sidewall of the platinum cruciblewith small amount of water (6.2). Transfer the solutionquantitatively to a 50-mL volumetric flask and make up tomark with water (6.2).11.3.2 For the determination of sodium in regular PATsample, the above sample solution need

41、s to be diluted 25 to 50times.11.4 Blank should be performed with the same procedure(11.1 11.3) without adding samples into the platinumcrucible.11.5 Pipette the sample solution and the blank solution todetermine the absorbance, and pipette water (6.2) alone beforeand after each reading.11.6 Make su

42、re that the concentrations of the testing ele-ments are in the range of the calibration curve. Dilute thesamples if necessary.NOTE 4No CRM for PAT is available commercially. Additionalstandard method may be used for periodic verification of the method. Therecoveries for all metals of interests in PA

43、T were found in the range of 92to 105 %.12. Calculation or Interpretation of Results12.1 Calculate the concentration of each metal in the sampleusing the following equation:X15C12 C0! 350 3nm(1)where:X1= concentration of the metal i in PAT sample mg/kg,C1= concentration of the metal i in PAT test so

44、lution, g/L,C0= concentration of the metal i in blank solution, g/L,50 = volume of the flask, mL,m = weight of PAT sample, g, andn = dilution factor.13. Report13.1 Report the average value of metal content in mg/kg, tothe nearest 0.001 mg/kg. If the concentration of sodium in PATsample is less than

45、0.001 mg/kg, the result should be reportedas 0.001 mg/kg. If the concentration of other metals in PATsample is less than 0.005 mg/kg, the results should be reportedas 0.005 mg/kg, respectively.13.2 Report the following information in the report.13.2.1 The complete identification of the sample tested

46、.13.2.2 Results of the test.13.2.3 Any abnormal situations observed during the test.14. Precision and Bias514.1 The precision of this test method is based on anintralaboratory study of Test Method D8207 conducted in2017. One laboratory tested one PAT sample for metals. Everytest result represents an

47、 individual determination. The labora-tory reported 20 replicate results for each analysis/materialcombination in order to estimate the repeatability limits of thestandard. Practice E691 was followed for the design andanalysis of the repeatability data; the details are given inResearch Report RR: RR

48、:D16-1067.14.1.1 Repeatability Limit (r)Two test results obtainedwithin one laboratory shall be judged not equivalent if theydiffer by more than the “r” value for that material; “r” is theinterval representing the critical difference between the two testresults for the same material, obtained by the

49、 same operatorusing the same equipment on the same day in the samelaboratory.14.1.1.1 Repeatability limits are listed in Table 2.14.2 BiasAt the time of the study, the test specimenschosen for analysis were not accepted reference materialssuitable for determining the bias for the test method, thereforeno statement on bias is being made.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1067. ContactASTM CustomerService at serviceastm.org.D8207 18315. Quality Guidelin