1、Designation: D4471 18Standard Test Method forPyridine Bases in Cresylic Acid by Direct Titration1This standard is issued under the fixed designation D4471; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of pyridineand other basic nitrogen impurities in crude and refinedcresylic acids streams,
3、 including mixtures.1.2 This test method is applicable for pyridine base levels of0.001 % to 0.5 %.1.3 In determining the conformance of the test results usingthis method to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29.1.4 The value
4、s stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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 safe
5、ty, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific hazard statements, see Section 8.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the
6、 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:2D3852 Practice for Sampling and Handling Phenol, Cresols,and Cresylic AcidD4
7、790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Other Document:OSHA Regul
8、ations, 29 CFR paragraphs 1910.1000 and1910.120033. Terminology3.1 For definitions of terms used in this test method seeTerminology D4790.4. Summary of Test Method4.1 This test method is a direct, nonaqueous titration tech-nique utilizing perchloric acid in acetic acid as titrant and thecresylic aci
9、d itself as titration solvent. Endpoints may beestablished potentiometrically as well as by indicator so thatthe method is applicable to highly colored as well as lightercolored materials. This test method will detect basic compo-nents other than pyridine bases should they be present. Allbasic compo
10、unds detected by this procedure are calculated andexpressed as percent pyridine.5. Significance and Use5.1 The pyridine base content of cresylic acids is importantin certain applications. This test method may be used as a toolfor quality control and specification purposes by producers andusers.6. Ap
11、paratus6.1 Titrimeter or pH meter, equipped with half cell orcombination glass pH and Ag/AgCl reference electrodes. Thepair of electrodes shall be mounted to extend well below theliquid level. Storage in water between titrations is essentialbecause prolonged immersion in nonaqueous medium signifi-ca
12、ntly deadens response.6.2 Buret, 50-mL capacity. For low pyridine base concen-trations: 10 mL burette that reads to 0.05 mL.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-bility of Subcommittee D16.
13、02 on Oxygenated Aromatics.Current edition approved June 1, 2018. Published July 2018. Originally approvedin 1985. Last previous edition approved in 2010 as D4471 10. DOI: 10.1520/D4471-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
14、eastm.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 of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.*A Summary of Changes section appea
15、rs at the end of this standardCopyright 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 Principl
16、es for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.3 Magnetic Stirrer, with TFE-fluorocarbon or glass cov-ered stirring bar.6.4 Autotitration Equipment may be used if available.7. Reagents
17、7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may
18、 beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Perchloric Acid Titrant (0.02 N in glacial acetic acid)Add 1.8 mL of 70 % perchloric acid (HClO4) to 1 L of glacialacetic acid and mix wel
19、l. To standardize, weigh accurately0.0800 to 0.0950 g of primary standard potassium acidphthalate in glacial acetic acid and titrate potentiometrically orto the indicator endpoint, as described in 10.2. Calculate thenormality, N, of the perchloric acid solution as follows:N 5WV 30.2041where:W = weig
20、ht of potassium acid phthalate, g, andV = volume of perchloric acid titrant consumed, mL.7.3 Potassium Acid Phthalate (KH C8H8O4), primarystandardDry for2hat110C.7.4 Quinaldine Red Indicator SolutionDissolve 0.2 g ofquinaldine red indicator in 100 g of glacial acetic acid.7.5 Titration SolventGlacia
21、l acetic acid (CH3CO2H) maybe used as an additional titration solvent in order to decreasethe viscosity of a particular sample or to keep it from freezing.8. Hazards8.1 Consult current OSHA regulations and suppliers SafetyData Sheets, and local regulations for all materials used in thistest method.9
22、. Sampling9.1 Samples of the material shall be taken in accordancewith Practice D3852.10. Procedure10.1 Weigh an appropriate amount of cresylic acid sampleinto the titration beaker. (A sample size of 100 g is suggestedif the expected pyridine base content is in the range of 0.001 to0.070 %.) Place a
23、 stirring bar in the beaker and, if desired, addabout 100 mL of titration solvent.10.2 The specimen is titrated with perchloric acid titrant andthe endpoint determined by either of the following methods:10.2.1 IndicatorAfew drops of quinaldine red indicator isadded to the solution. The titration is
24、terminated when the redcolor disappears and the color of the sample returns to itsoriginal hue.10.2.2 PotentiometricThe electrodes are inserted into thespecimen and the observed potentials are plotted as a functionof the titrant volume consumed. The point where E/V is thegreatest is taken as the end
25、point.10.3 Repeat 10.1 through 10.2, but with no specimen toobtain a reagent blank when titration solvent is used.11. Calculation11.1 Results are calculated as weight percent pyridine, P,asfollows:P 57.91 3 N 3VS2 VB!Wwhere:N = normality of the perchloric acid titrant,VS= titrant consumed for the sa
26、mple, mL,VB= titrant consumed for the reagent blank, mL, andW = specimen weight, g.12. Report12.1 Report the percent of pyridine bases to the nearest0.001 %.13. Precision and Bias13.1 PrecisionThe following criteria shall be used forjudging the acceptability of results.13.1.1 Intermediate Precision
27、(within laboratory)Whenusing the visual endpoint in this test method, results obtainedby different analysts in the same laboratory should be suspectwithin 95 % confidence limits if they differ by more than 2.8 %of the average of values determined. When using the potentio-metric endpoint in this test
28、 method, results obtained bydifferent analysts in the same laboratory should be suspectwithin 95 % confidence limits if they differ by more than 2.2 %of the average of values determined.13.1.2 Reproducibility (between laboratories)When usingthe visual endpoint in this test method, results obtained b
29、yanalysts in different laboratories should be suspect within 95 %confidence limits if they differ by more than 6.8 % of theaverage of values determined. When using the potentiometricendpoint in this test method, results obtained by analysts indifferent laboratories should be suspect within 95 % conf
30、idencelimits if they differ by more than 13.9 % of the average ofvalues determined.13.2 BiasSince there is no accepted reference materialsuitable for determining the bias in this test method formeasuring pyridine bases, bias has not been determined.13.3 Additional Information:13.3.1 A single lab ana
31、lyzed a quality control sample 101times. The average was 0.00465 wt. %. The standard deviationwas 0.00007 wt. %. Repeatability = 0.00019.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the
32、 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.D4471 18214. Quality Guidelines14.1 Laboratories shall have a quality control sy
33、stem inplace.14.1.1 Confirm the performance of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.14.1.2 A quality control sample is a stable material isolatedfrom the production process and representative
34、 of the samplebeing analyzed.14.1.3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.14.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD680
35、9 or similar statistical quality control practices.15. Keywords15.1 cresols; cresylic acids; nitrogen bases; phenol; pyridinebases; tar acidsSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue (D447110)that may impact the use of this
36、standard. (Approved June 1, 2018.)(1) Added additional information on a single lab repeatabilityto the precision statement.(2) Added to 6.2For low pyridine base concentrations: 10mL burette that reads to 0.05 mL.ASTM International takes no position respecting the validity of any patent rights assert
37、ed in connection with any item mentionedin this standard. Users of this standard are 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 t
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39、 careful consideration at a meeting of theresponsible technical committee, which you 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 Interna
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