1、Designation: D 2086 03Standard Test Method forAcidity in Vinyl Acetate and Acetaldehyde1This standard is issued under the fixed designation D 2086; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of totalacidity as acetic acid in refined vinyl acetate and acetaldehyde.1.2 The values stated in
3、 SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 For purposes of determining conformance of an ob-served value or a calculated value using this test method torelevant specifications, test result(s) shall be rounded off “tothe nearest unit” in t
4、he last right-hand digit used in expressingthe specification limit, in accordance with the rounding-offmethod of Practice E 29.1.4 For hazard information and guidance, see the suppliersMaterial Safety Data Sheet.1.5 This standard does not purport to address all of thesafety concerns, if any, associa
5、ted 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. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:D 1193 Specific
6、ation for Reagent Water2E 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3E 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis43. Summary of Test Method3.1 The specimen is mixed with eit
7、her an equal volume ofchilled water or an equal volume of ethyl alcohol and titratedat reduced temperature with aqueous sodium hydroxide solu-tion to a phenolphthalein end point.4. Significance and Use4.1 This test method provides a measurement of total acidityin vinyl acetate and acetaldehyde. The
8、results of these mea-surements can be used for specification acceptance.5. Interferences5.1 Any material or contaminant that will react with NaOHunder the test conditions will affect the results.5.2 Vinyl acetate will decompose on storage, typically byway of hydrolysis, to form acetic acid.5.3 Aceta
9、ldehyde will react with oxygen, either dissolved orin a storage container, to form acetic acid.5.4 Various acids or other acidic materials may be present.Common practice, including the method used here, calculatesthese as acetic acid. The actual weight percent of acidicmaterials may be different.6.
10、Apparatus6.1 Buret, 10-mL, graduated in 0.05-mL subdivisions.6.2 Erlenmeyer Flask, 250-mL capacity.6.3 Graduated Cylinder, 50 or 100-mL capacity.6.4 Cold Bath, maintained at 0C or below.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it
11、 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.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its
12、use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type IV of Specification D 1193.7.3 Ethyl Alcohol (Ethanol), 95 volume %, minimum.1This test method is under the jurisdictio
13、n of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.35 on Solvents, Plasticizers, and Chemical Intermediates.Current edition approved Oct. 1, 2003. Published October 2003. Originallyapproved in 1962. Last previous edit
14、ion approved in 2002 as D 2086 02.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 14.02.4Annual Book of ASTM Standards, Vol 15.05.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of re
15、agents 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.1*A Summary of Changes section appears at the end of this
16、 standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1Denatured ethyl alcohol conforming to Formula No. 3A of theU.S. Bureau of Alcohol, Tobacco and Firearms is suitable for use as asolvent.7.4 Phenolphthalein Indicator Solu
17、tion (10 g/L)Dissolve1 g of phenolphthalein in 100 mL of methanol, ethanol, orisopropanol.7.5 Sodium Hydroxide, Standard Solution (0.05 N)Prepare and standardize a 0.05 N sodium hydroxide (NaOH)solution (Note 2) in accordance with the Sodium HydroxideSolution sections of Practice E 200.NOTE 2Alterna
18、tively, potassium hydroxide (KOH) solution may beused.7.6 Bromothymol Blue Indicator (10g/L)Dissolve1gofbromothymol blue in 100 mL of methanol, ethanol, or isopro-panol.7.7 Sodium Hydroxide, Standard Solution (0.02 N)Prepare and standardize a 0.02 N sodium hydroxide (NaOH)solution (Note 3) in accord
19、ance with the Sodium HydroxideSolution sections of Practice E 200.NOTE 3Alternatively, potassium hydroxide (KOH) solution may beused. If the titration solution becomes cloudy due to water saturationduring titrations, 0.02 N alcoholic KOH may be used as the titrant.8. Hazards8.1 Vinyl acetate and ace
20、taldehyde are flammable andhazardous as their vapors form explosive mixtures with air.8.2 Acetaldehyde boils at 21C; therefore, store in pressurecontainers or refrigerate if kept in glass containers. Wear safetygoggles or a full face shield when handling acetaldehyde.9. Procedure for Vinyl Acetate (
21、Warningsee Section 8)9.1 If a solvent is to be utilized, add 50 mL of ethanol oranhydrous methanol. Alternatively, the vinyl acetate may betitrated neat.9.2 If a solvent is utilized, add 0.5 mL bromothymol blueindicator to the solvent and titrate with 0.02 N NaOH solutionto the first blue color.9.3
22、Add 50 mL of the specimen from a graduated cylinderand cool the solution to approximately 0C in a cold bath(alternatively, chill in refrigerator for 15 min. If a solvent is notused and the indicator was not added in 9.2, add 0.5 mL ofbromothymol blue indicator. The solution may be purged toremove an
23、y absorbed carbon dioxide.9.4 Titrate with the 0.02 N NaOH solution to the blue color.10. Procedure for Acetaldehyde (Warningsee Section 8)10.1 Measure into a 250-mL Erlenmeyer flask 50 mL ofwater and add sufficient crushed ice (prepared from reagentwater) so that some ice will remain at the end of
24、thedetermination.NOTE 4Titration at low temperature avoids interference and is re-quired because of the low boiling point of acetaldehyde.10.2 Add 0.5 mL of phenolphthalein indicator solution andtitrate with 0.05 N NaOH solution to the first perceptible pinkcolor.10.3 By means of a graduated cylinde
25、r add 50 mL of theacetaldehyde specimen that previously has been chilled to 0 to5C.10.4 Titrate immediately with the 0.05 N NaOH solution tothe same first perceptible pink color originally obtained in 10.2.11. Calculation11.1 Calculate the acidity A of the specimen as follows:11.1.1 Acidity as weigh
26、t % acetic acid:A 5 VN 3 0.060 3 100!/50 D 5 VN 3 0.12!/D (1)or11.1.2 Acidity as milligrams KOH per gram of specimen:5 VN 3 0.056 3 1000!/50 D 5 VN 3 1.12!/D (2)where:V = volume of NaOH solution required for titration ofthe specimen, mL,N = normality of the NaOH solution,D = density of specimen in g
27、/mL,0.060 = milliequivalent weight of acetic acid, and0.056 = milliequivalent weight of KOH.12. Report12.1 Report the following information:12.1.1 The percent of acetic acid to the nearest 0.0001 %.12.1.2 Vinyl AcetateAcceptable duplicate determinationsfor averaging have not yet been determined.12.1
28、.3 AcetaldehydeDuplicate determinations that agreewithin 0.010 %, absolute, are acceptable for averaging (95 %confidence level).13. Precision and Bias13.1 The following criteria should be used for determiningthe acceptability of results at the 95 % confidence level.13.2 Vinyl Acetate:13.2.1 Repeatab
29、ilityThe repeatability of this test methodhas not yet been determined.13.2.2 ReproducibilityThe standard deviation of results(each the average of duplicates), obtained by analysts indifferent laboratories, has been estimated at 0.0002 wt. %absolute with 3 df. The 95 % limit for differences between t
30、wosuch averages is estimated at 0.0006 wt. %.NOTE 5The statistical data was determined with only two laboratoryparticipants and will be utilized only until a complete round robin studycan be completed.13.3 Acetaldehyde:13.3.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obta
31、ined by the same analyst should beconsidered suspect if they differ by more than 0.014 %absolute.13.3.2 ReproducibilityTwo results, each the mean of du-plicate determinations, obtained by analysts in different labo-ratories should be considered suspect if they differ by morethan 0.035 %, absolute.NO
32、TE 6The above precision estimates are based on an interlaboratorystudy on samples of acetaldehyde containing 0.034 and 0.146 % aceticacid. Each sample was analyzed in duplicate by two analysts in each offive different laboratories on two different days.13.4 BiasBias has not been determined for this
33、testmethod because an appropriate standard is not available (seeSection 5).D208603214. Keywords14.1 acetaldehyde; acidity; vinyl acetateSUMMARY OF CHANGESCommittee D01.35 has identified the location of selected changes to this standard since the last issue(D 2086 - 02) that may impact the use of thi
34、s standard.(1) Changed the definition of “D” gravity in equations 1 and 2in 11.1.1 and 11.1.2 from specific gravity to “density in g/mL.”ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this sta
35、ndard 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 the responsible technical committee and must be reviewed every five years an
36、dif not 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,
37、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 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).D2086033
