1、Designation: D2086 08 (Reapproved 2012)Standard Test Method forAcidity in Vinyl Acetate and Acetaldehyde1This standard is issued under the fixed designation D2086; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 totalacidity as acetic acid in refined vinyl acetate and acetaldehyde.1.2 The v
3、alues stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 near
4、est unit” in the last right-hand digit used in expressingthe specification limit, in accordance with the rounding-offmethod of Practice E29.1.4 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
5、 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 limitations prior to use. For specific hazardstatements, see Section 8.2. Referenced Documents2.1 ASTM Standards:2D
6、1193 Specification for Reagent WaterE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE200 Practice for Preparation, Standardization, and Storageof Standard and Reagent Solutions for Chemical Analysis3. Summary of Test Method3.1 The specimen is mixed w
7、ith either 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 acetaldehyd
8、e. The 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.
9、3 Acetaldehyde 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 differ
10、ent.6. 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 indica
11、ted, 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.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to perm
12、it its use without lessening theaccuracy of the determination.1This test method is under the jurisdiction 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.Curre
13、nt edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1962. Last previous edition approved in 2008 as D2086 08. DOI:10.1520/D2086-08R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book
14、 of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Ana
15、lar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959. United States17.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type IV or higher purity of Specification D1193.7.3 Ethyl Alcohol (Ethanol), 95 volume %, minimum.NOTE 1Denatured e
17、thyl alcohol conforming to Formula No. 3Aof theU.S. Bureau of Alcohol, Tobacco and Firearms is suitable for use as asolvent.7.4 Phenolphthalein Indicator Solution (10 g/L)Dissolve1 g of phenolphthalein in 100 mL of methanol, ethanol, orisopropanol.7.5 Sodium Hydroxide, Standard Solution (0.05 N)Prep
18、are and standardize a 0.05 N sodium hydroxide (NaOH)solution (Note 2) in accordance with the Sodium HydroxideSolution sections of Practice E200.NOTE 2Alternatively, potassium hydroxide (KOH) solution may beused.7.6 Bromothymol Blue Indicator (10g/L)Dissolve1gofbromothymol blue in 100 mL of methanol,
19、 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 accordance with the Sodium HydroxideSolution sections of Practice E200.NOTE 3Alternatively, potassium hydroxide (KOH) solution may beused. If the tit
20、ration 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 acetaldehyde are flammable andhazardous as their vapors form explosive mixtures with air.8.2 Acetaldehyde boils at 21C; therefore, store in pressur
21、econtainers or refrigerate if kept in glass containers. Wear safetygoggles or a full face shield when handling acetaldehyde.9. Procedure for Vinyl Acetate (Warningsee Section 8)9.1 If a solvent is to be utilized, add 50 mL of ethanol oranhydrous methanol. Alternatively, the vinyl acetate may betitra
22、ted 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 Add 50 mL of the specimen from a graduated cylinderand cool the solution to approximately 0C in a cold bath(alternatively, chill in refrigerator
23、 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 any 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
24、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 thedetermination.NOTE 4Titration at low temperature avoids interference and isrequired because of the low boiling point of acetaldehyde.10.2 Add
25、 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 cylinder 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 sa
26、me 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 weight % acetic acid:A 5 VN 30.060 3100!/50 D 5 VN 30.12!/D (1)or11.1.2 Acidity as milligrams KOH per gram of specimen:5VN 30.056 31000!/50 D 5 VN 31.1
27、2!/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/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 pe
28、rcent of acetic acid to the nearest 0.0001 %.12.1.2 Vinyl AcetateAcceptable duplicate determinationsfor averaging have not yet been determined.12.1.3 AcetaldehydeDuplicate determinations that agreewithin 0.010 %, absolute, are acceptable for averaging (95 %confidence level).13. Precision and Bias13.
29、1 The following criteria should be used for determiningthe acceptability of results at the 95 % confidence level.13.2 Vinyl Acetate:13.2.1 RepeatabilityThe repeatability of this test methodhas not yet been determined.13.2.2 ReproducibilityThe standard deviation of results(each the average of duplica
30、tes), obtained by analysts indifferent laboratories, has been estimated at 0.0002 wt. %absolute with 3 df. The 95 % limit for differences between twosuch averages is estimated at 0.0006 wt. %.NOTE 5The statistical data was determined with only two laboratoryparticipants and will be utilized only unt
31、il a complete round robin studycan be completed.13.3 Acetaldehyde:13.3.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same analyst should beconsidered suspect if they differ by more than 0.014 %absolute.D2086 08 (2012)213.3.2 ReproducibilityTwo results, each
32、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.NOTE 6The above precision estimates are based on an interlaboratorystudy on samples of acetaldehyde containing 0.034 and 0.146 % aceticacid
33、. 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 testmethod because an appropriate standard is not available (seeSection 5).14. Keywords14.1 acetaldehyde; acidity; vinyl acetateSUMMARY O
34、F CHANGESCommittee D01.35 has identified the location of selected changes to this standard since the last issue(D2086 - 03) that may impact the use of this standard. (Approved November 1, 2008.)(1) Revised 7.2.ASTM International takes no position respecting the validity of any patent rights asserted
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38、onal, 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/).D2086 08 (2012)3
