1、Designation: D4471 10Standard 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 and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D3852 Practice for Sampling and Handling Phenol,Cresols, and Cresylic AcidD4790 Terminology ofAromatic Hydrocarbons
6、 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 Regulations, 29 CFR paragraphs 1910.1000 and1
7、910.120033. 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 acid itself as titration solvent. Endpoints
8、 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 compounds detected by this procedure are calc
9、ulated 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. Apparatus6.1 Titrimeter or pH meter, equip
10、ped 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-cantly deadens response.6.2 Buret, 50-mL c
11、apacity.6.3 Magnetic Stirrer, with TFE-fluorocarbon or glass cov-ered stirring bar.6.4 Autotitration Equipment may be used if available.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended that1This test method is under the ju
12、risdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.02 on Oxygenated Aromatics.Current edition approved Jan. 1, 2010. Published January 2010. Originallyapproved in 1985. Last previous edition approved in 2004 as D4471 00
13、(2004).DOI: 10.1520/D4471-10.2For 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.3Available from U.S. Government
14、Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.all reagents s
15、hall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccura
16、cy 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 well. To standardize, weigh accurately0.0800 to 0.0950 g of primary standard potassium acidphthalate in glacial acetic acid and titrate p
17、otentiometrically orto the indicator endpoint, as described in 10.2. Calculate thenormality, N, of the perchloric acid solution as follows:N 5WV 3 0.2041where:W = weight of potassium acid phthalate, g, andV = volume of perchloric acid titrant consumed, mL.7.3 Potassium Acid Phthalate (KH C8H8O4), pr
18、imarystandardDry for2hat110C.7.4 Quinaldine Red Indicator SolutionDissolve 0.2 g ofquinaldine red indicator in 100 g of glacial acetic acid.7.5 Titration SolventGlacial acetic acid (CH3CO2H) maybe used as an additional titration solvent in order to decreasethe viscosity of a particular sample or to
19、keep it from freezing.8. Hazards8.1 Consult current OSHA regulations and suppliers Mate-rial Safety Data Sheets, and local regulations for all materialsused in this test method.9. Sampling9.1 Samples of the material shall be taken in accordancewith Practice D3852.10. Procedure10.1 Weigh an appropria
20、te 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 stirring bar in the beaker and, if desired, addabout 100 mL of titration solvent.10.2 The specimen is titrated with perch
21、loric 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 terminated when the redcolor disappears and the color of the sample returns to itsoriginal hue.10.2.2 PotentiometricThe el
22、ectrodes are inserted into thespecimen and the observed potentials are plotted as a functionof the titrant volume consumed. The point where DE/DV is thegreatest is taken as the endpoint.10.3 Repeat 10.1 through 10.2, but with no specimen toobtain a reagent blank when titration solvent is used.11. Ca
23、lculation11.1 Results are calculated as weight percent pyridine, P,asfollows:P 57.91 3 N 3 VS2 VB!Wwhere:N = normality of the perchloric acid titrant,VS= titrant consumed for the sample, mL,VB= titrant consumed for the reagent blank, mL, andW = specimen weight, g.12. Report12.1 Report the percent of
24、 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 (within laboratory)Whenusing the visual endpoint in this test method, results obtainedby different analysts in the same
25、 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 method, results obtained bydifferent analysts in the same laboratory should be suspectwithin 95 % confidence limits if
26、 they differ by more than 2.2 %of the average of values determined.13.1.2 Reproducibility (between laboratories)When us-ing the visual endpoint in this test method, results obtained byanalysts in different laboratories should be suspect within 95 %confidence limits if they differ by more than 6.8 %
27、of theaverage of values determined. When using the potentiometricendpoint in this test method, results obtained by analysts indifferent laboratories should be suspect within 95 % confidencelimits if they differ by more than 13.9 % of the average ofvalues determined.13.1.3 BiasThe bias of this test m
28、ethod cannot be deter-mined because no referee method is available to determine thetrue value.14. Quality Guidelines14.1 Laboratories shall have a quality control system inplace.14.1.1 Confirm the performance of the test instrument ortest method by analyzing a quality control sample followingthe gui
29、delines of standard statistical quality control practices.14.1.2 A quality control sample is a stable material isolatedfrom the production process and representative of the samplebeing analyzed.14.1.3 When QA/QC protocols are already established inthe testing facility, these protocols are acceptable
30、 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 GuideD6809 or similar statistical quality control practices.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Socie
31、ty, Washington, 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.D
32、4471 10215. 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(D4471 - 00 (2004) that may impact the use of this standard. (Approved January 1, 201
33、0.)(1) Added Quality Guidelines Section 14.(2) Added Guide D6809 to Referenced Documents section2.1.(3) Added information concerning units section 1.4(4) Replaced mention of the Mercury calomel electrodes withthe more commonly used silver-silver chloride reference elec-trodes in section 6.1.ASTM Int
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35、y 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 revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand sh
36、ould be addressed to ASTM International Headquarters. Your comments will receive 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 St
37、andards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United 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 also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D4471 103
