1、Designation: D8032 16Standard Test Method forAcid Number of Terephthalic Acid by Color-IndicatorTitration1This standard is issued under the fixed designation D8032; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 acidnumber of terephthalic acid (TA) by color-indicator titration.Acid number o
3、f TA product is usually within 674 to 676 mgKOH/g.1.2 In determining the conformance of the test results usingthis method, results shall be rounded off in accordance with therounding-off method of Practice E29.1.3 The values stated in SI units are to be regarded asstandard. No other units of measure
4、ment are included in thisstandard.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 and health practices and determine the applica-bility of regulatory limita
5、tions prior to use.2. Referenced Documents2.1 ASTM Standards:2D974 Test Method for Acid and Base Number by Color-Indicator TitrationD1193 Specification for Reagent WaterD4790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quality AssuranceProcedures for
6、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 Practice for Conducting an Interl
7、aboratory Study toDetermine the Precision of a Test Method2.2 Other Document:3OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.12003. Terminology3.1 Definitions:3.1.1 acid number, nthe quantity of base, expressed inmilligrams of potassium hydroxide per gram of sample that isrequired to titrate
8、a sample in a specified solvent to a specifiedend point.4. Summary of Test Method4.1 A TA sample is dissolved in dimethyl sulfoxide andtitrated with standard sodium hydroxide solution to the endpoint indicated by the color change of the added phenolphtaleinsolution (colorless in acid and pink in bas
9、e). The acid numberis calculated as milligrams of KOH per gram of TA sample. Itstheoretical value of TA sample is 675.5 mg KOH/g.5. Significance and Use5.1 An estimate of TA purity can be determined by titratingwith KOH. As an index of TA purity, the acid number can beused as a guide in the quality
10、control of TA production.6. Apparatus6.1 Analytical Balance, capable of weighing 60.0001 g.6.2 Burets, 50-mL with 0.1-mL graduations.7. Reagents7.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the reagent gradespecification of the Analytical Reagents
11、 of the American1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.02 on Oxygenated Aromatics.Current edition approved March 1, 2016. Published June 2016. DOI: 10.1520/D8032-16.2For refer
12、enced 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 U.S. Government Printing Office, Superintendent ofDocum
13、ents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http:/www.access.gpo.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Chemical Society,4where such specifications are available.Other grades may be used, provided it is first
14、 ascertained thatthe reagent is of sufficient high purity to permit its use withoutlessening the performance or accuracy of the determination.Reagent chemicals shall be used for all tests.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type III of Specif
15、icationD1193. Boil the water gently for 5 to 10 min to remove anyCO2and cool the water to room temperature.7.3 Dimethyl Sulfoxide(WarningFlammable and harm-ful if inhaled, swallowed or absorbed through the skin.).7.4 Sodium Hydroxide Solution (0.5 M)Weigh 20 g ofsodium hydroxide (NaOH) (WarningHighl
16、y corrosive to allbody tissue.) in a beaker. Add 100 mL water (boiling gently for5 to 10 min and cooling to room temperature, free of CO2)todissolve and cool the solution. Then quantitatively transfer thesolution into a 1000 mL volumetric flask and dilute to volumewith the above water. The NaOH solu
17、tion should be stored ina plastic bottle and stopper must be stressed.NOTE 1After standardization, the NaOH solution should not be storedin a glass container because it will be slowly neutralized from exposure toa glass container. It will also “cement” a glass stopper into a glasscontainer.7.5 Ethan
18、ol.7.6 Phenolphthalein Indicator Solution (1 g/L)Dissolve0.1 g solid phenolphthalein in 100 mL ethanol.7.7 Potassium Hydrogen Phthalate.8. Hazards8.1 Consult current federal regulations, suppliers SafetyData Sheets, and local regulations for all materials used in thistest method.9. Sampling, Test Sp
19、ecimens, and Test Units9.1 Use only representative samples obtained as describedin Practice E300, unless otherwise specified.10. Standardization of Titrant10.1 Place 10 to 20 g of primary standard potassiumhydrogen phthalate in a weighing bottle and dry at 120C for2 h. Close the weighing bottle and
20、cool in a desiccator.10.2 Weigh, to the nearest 0.0001 g, 4.5 to 5.0 g of the driedpotassium hydrogen phthalate and transfer to a 250-mL Erlen-meyer flask. Add 100 mL of CO2-free water and stir gently todissolve the sample.10.3 Add 3 drops of phenolphthalein indicator solution andtitrate with 0.5 M
21、NaOH solution (7.4) until one drop of NaOHchanges the color of the solution from colorless to pink.10.4 Perform a blank titration by repeating the above stepswithout adding potassium hydrogen phthalate.10.5 Calculate the molarity of the NaOH solution as fol-lows:C 5m 3 1000M 3 V 2 V0!(1)where:C = mo
22、larity of NaOH solution, mol/L,V = NaOH solution required for titration of the potassiumhydrogen phthalate (10.3), mL,V0= NaOH solution required for titration of the potassiumhydrogen phthalate (10.4), mL,M = 204.23 g/mol, molar mass of the potassium hydrogenphthalate (7.7), andm = mass of potassium
23、 hydrogen phthalate titrated, g.11. Procedure11.1 Weigh, to the nearest 0.0001 g, 0.8 to 1.5 g of TAsample, into a 250-mL flask, and add 20 mL of dimethylsulfoxide with swirling to dissolve TA completely.11.2 Add 20 mL of CO2-free water, and 0.1 mL of thephenolphthalein indicator solution into the f
24、lask.11.3 Titrate using the standard NaOH solution and swirlflask contents gently during titration to a 15-s pink end point.Record the amount of titrant required.11.4 Perform a blank titration by repeating the above stepswithout adding the TA sample.12. Calculation12.1 Calculate the acid number as f
25、ollows:Acid number, mg of KOH / g 5 A 2 B! 3 C 3 M# W(2)where:A = NaOH solution required for titration of the TA sample(11.3), mL,B = NaOH solution required for titration of the blank (11.4),mL,C = molarity of the NaOH solution (10.5), mol/L,M = 56.11 g/mol, molar mass of the KOH, andW = mass of TA
26、sample titrated, g.13. Report13.1 Report the value of acid number in mg KOH/g, to thenearest 0.1 unit.13.2 Report the following information in the report:13.2.1 The complete identification of the sample tested.13.2.2 Any deviation from the procedure specified (forexample operating conditions).13.2.3
27、 Results of the test.13.2.4 Any abnormal situations observed during the test.14. Precision and Bias14.1 The precision of this method is based on an intralabo-ratory study of Test Method D8032 conducted in 2015. Onelaboratory tested one TA sample for acid number by color-indicator titration. Every te
28、st result represents an individualdetermination. The laboratory reported 20 replicate results foreach analysis/material combination in order to estimate the4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagen
29、ts 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.D8032 162repeatability limits of the standard. Practice E691
30、was followedfor the design and analysis of the repeatability data; the detailsare given in Research Report RR:D16-1058.514.1.1 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”istheinte
31、rval representing the critical difference between two testresults for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaboratory.14.1.1.1 Repeatability limits are listed in Table 1.14.1.2 Reproducibility has not been determined and will bedetermine
32、d within five years.14.2 BiasAt the time of the study, the test specimenschosen for analysis were not accepted reference materialssuitable for determining the bias for this test method, thereforeno statement on bias is being made.15. Quality Guidelines15.1 Laboratories shall have a quality control s
33、ystem inplace.15.1.1 Confirm the performance of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.15.1.2 A quality control sample is a stable material isolatedfrom the production process and representativ
34、e of the samplebeing analyzed.15.1.3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.15.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD68
35、09 or similar statistical quality control practices.16. Keywords16.1 acid number; color-indicator titration; terephthalic acid(TA)ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard a
36、re expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not
37、 revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which y
38、ou may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,Unite
39、d States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may al
40、so be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1058. ContactASTM CustomerService at serviceastm.org.TABLE 1 Repeatability Limits (TA)Color-IndicatorTitrationAverage(mg KOH/g)XRepeatabilityStandardDeviationSrRepeatabilityLimitracid number 675.2 0.49 1.36D8032 163
