ASTM E298-17a Standard Test Methods for Assay of Organic Peroxides.pdf

1、Designation: E298 17aStandard Test Methods forAssay of Organic Peroxides1This standard is issued under the fixed designation E298; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses i

2、ndicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the assay of organic peroxides.Two procedures are given, depending upon the ease of reduc-tion:1.1.1 Sodium Iodide, Room Temperature

3、 Test Method, fororganic peroxides easy to reduce, and1.1.2 Sodium Iodide, 60C Test Method, for organic perox-ides that are moderately stable.1.2 Review the current Safety Data Sheets (SDS) for de-tailed information concerning toxicity, first-aid procedures, andsafety precautions.1.3 The values stat

4、ed in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.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 he

5、alth practices and determine the applica-bility of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,

6、Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-teria

7、lsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals (Withdrawn 2009)3E200 Practice for Preparation, Standardization, and Storageof Standard and Reagent Solutions for Chemical Analysis3. Significance and Use3.1 Organic peroxides

8、 are widely used as chemicalintermediates, catalysts, and initiators. These test methodsprovide procedures for assaying organic peroxides to deter-mine if they are suitable for their intended use.4. Purity of Reagents4.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless oth

9、erwise 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 beused, provided it is first ascertained that the reagent is ofsufficiently high p

10、urity to permit its use without lessening theaccuracy of the determination.4.2 Unless otherwise indicated, references to water shall beunderstood to mean Type II or Type III reagent water conform-ing to Specification D1193.SODIUM IODIDE, ROOM TEMPERATURE TESTMETHOD5.1 This test method covers the ass

11、ay of organic peroxidesthat are easily reduced, such as hydroperoxides and diacylperoxides. Dialkyl peroxides do not react, while peresters andbridge-type peroxides like ascaridole react slowly and incom-pletely.5.2 Specific peroxides that can be analyzed by this proce-dure include the following:5.2

12、.1 Diacyl PeroxidesBenzoyl 2,4-dichlorobenzoyl,p-chlorobenzoyl, lauroyl, acetyl, and decanoyl peroxides.1These test methods are under the jurisdiction of ASTM Committee D16 onAromatic, Industrial, Specialty and Related Chemicals and are the direct responsi-bility of Subcommittee D16.15 on Industrial

13、 and Specialty General Standards.Current edition approved July 1, 2017. Published July 2017. Originally approvedin 1966. Last previous edition approved in 2017 as E298 17. DOI: 10.1520/E0298-17a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at

14、serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Soc

15、iety, 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

16、.*A Summary of Changes section appears 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 est

17、ablished in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.2.2 Dibasic Acid PeroxideSuccinic acid peroxide.5.2.3 Ketone PeroxidesCyclohexanone peroxide andmethy

18、l ethyl ketone peroxide.5.2.4 Alkyl Hydroperoxidestert-Butylhydroperoxide and2,5-dimethylhexane-2,5-dihydroperoxide.6. Summary of Test Method6.1 A sample is dissolved in a mixture of methylenechloride and acetic acid. A saturated solution of sodium iodideis added and the mixture is allowed to react

19、in the dark at roomtemperature for 15 min. The liberated iodine is then titratedwith standard sodium thiosulfate solution.7. Interferences7.1 Conjugated diolefins interfere by absorbing iodine.8. Apparatus8.1 Iodine Flasks, 250-mL, with stoppers.NOTE 1All glassware should be thoroughly cleaned befor

20、e use.9. Reagents9.1 Acetic Acid, Glacial.9.2 Carbon Dioxide, cylinder.9.3 Methylene Chloride.9.4 Sodium Iodide, Saturated SolutionPrepare a saturatedsolution of sodium iodide (NaI) in de-aerated water. Thissolution should be prepared just prior to use and kept in anamber bottle.9.5 Sodium Thiosulfa

21、te, Standard Solution (0.1 meq/mL(N)Prepare and standardize a 0.1 meq/mL(N) solution ofsodium thiosulfate (Na2S2O3) in accordance with the appropri-ate sections of Practice E200.9.6 Starch Indicator Solution (10 g/L), Prepare as describedin the appropriate sections of Practice E200.9.7 Water, De-aer

22、atedPass carbon dioxide (CO2) throughdistilled water for several minutes prior to use.10. Procedure10.1 Add 20 mL of acetic acid to a 250-mL iodine flask andsparge with a rapid flow of CO2for 2 min. Stopper the flaskand reserve for the sample.10.2 Accurately weigh a sample containing 3 to 4 meq ofac

23、tive oxygen to the nearest 0.1 mg and transfer to the flask.Volatile liquid peroxides may be diluted to a known volumewith acetic acid and aliquots taken for analysis.NOTE 2The approximate weight of the sample to be used in theanalysis may be calculated as follows:Sample weight, g 5 3.5M/2C 31000 (1

24、)where:M = molecular weight of the compound, andC = number of peroxide groups in the molecule.10.3 Add 10 mL of methylene chloride and restopper. Swirlbriefly to dissolve the sample.10.4 Add 5 mL of freshly prepared saturated NaI solution.Restopper and swirl. Place a few millilitres of water in the

25、wellof the flask and allow to stand in the dark at room temperaturefor 15 min.10.5 Add 50 mL of de-aerated water and titrate with 0.1meq/mL (N)Na2S2O3solution until the solution is a pale strawcolor. Add 1 to 2 mL of starch solution and continue thetitration to the sharp disappearance of the blue co

26、lor. Recordthe number of millilitres required for titration.10.6 Subtract the number of millilitres required for titrationof a blank carried through the entire procedure and calculatethe assay value of the sample.NOTE 3The blank titration should normally require 0.05 mL or less of0.1 meq/mL (N)Na2S2

27、O3solution. The results should be discarded andthe analysis repeated if high blank values are obtained.11. Calculation11.1 Calculate the assay as follows:Assay, as percent compound 5 A 2 B! 3 N 3 M 3100/W 32C31000 (2)where:A =mLofNa2S2O3solution required for titration of thesample,B =mLofNa2S2O3solu

28、tion required for titration of theblank,N = meq/mL (N) of the Na2S2O3solution,C = number of peroxide groups in the molecule,M = molecular weight of the compound, andW = grams of sample used.11.2 Calculate the percent active oxygen in the compoundas follows:Active oxygen, % 5 A 2 B! 3 N 30.008 3100/W

29、 (3)11.3 If required, the percent active oxygen can be convertedto a specific peroxide using the appropriate conversion factor.Peroxide X,%5 % Active Oxygen in Peroxide X 3 F (4)where:F = conversion factor for CompoundX11.3.1 Conversion Factors for some common peroxides areas follows:Cumene Hydroper

30、oxide = 9.5125Benzoyl Peroxide = 15.140t-Butyl Hydroperoxide = 5.6328Lauroyl Peroxide = 24.91512. Report12.1 Report the assay value of the compound to the nearest0.01 %.13. Precision and Bias513.1 The following criteria shall be used for judging theacceptability of results (Note 4):5Supporting data

31、have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:E15-1001. ContactASTM CustomerService at serviceastm.org.E298 17a213.1.1 Repeatability (Single Analyst)The standard devia-tion for a single determination has been estimated to be0.047 % absolute at

32、 36 df. The 95 % limit for the differencebetween two such determinations is 0.13 % absolute.13.1.2 Laboratory Precision (Within-Laboratory, Between-Days Variability)The standard deviation of results (each theaverage of duplicates) obtained by the same analyst ondifferent days, has been estimated to

33、be 0.010 % absolute at 18df. The 95 % limit for the difference between two suchaverages is 0.028 % absolute.13.1.3 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of duplicates) obtained byanalysts in different laboratories has been estimated to be0.035 % absolu

34、te at 5 df. The 95 % limit for the differencebetween two such averages is 0.10 % absolute.NOTE 4These precision estimates are based on an interlaboratorystudy in which 3 samples were analyzed. One analyst in each of 6laboratories performed duplicate determinations and repeated them on asecond day, f

35、or a total of 72 determinations. Practice E180 was used indeveloping these statements.13.2 BiasThe bias of this test method has not beendetermined due to the lack of suitable reference materials ormethodology.14. Quality Guidelines14.1 Laboratories shall have a quality control system inplace.14.1.1

36、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 of the samplebeing

37、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 GuideD6809 or similar statist

38、ical quality control practices.SODIUM IODIDE, 60C TEST METHOD15. Scope15.1 This test method covers the assay of organic peroxidesthat are moderately stable, such as peresters, di-acyl peroxides,and n-alkyl peroxides. These peroxides react slowly withsodium iodide at room temperature, but do not requ

39、ire the useof hydroiodic acid.15.2 Specific peroxides that can be analyzed by this proce-dure include the following: t-butyl peracetate, t-butylperoxyisobutyrate, di-t-butyl diperphthalate, t-butylperbenzoate, and 2,2-bis(t-butylperoxy) butane.16. Summary of Test Method16.1 A sample is dissolved in

40、glacial acetic acid. Saturatedsodium iodide solution is then added and the mixture isallowed to react for1hat60C. The liberated iodine is titratedwith standard sodium thiosulfate solution.17. Interferences17.1 Conjugated diolefins interfere under the conditions ofanalysis by absorbing iodine.18. App

41、aratus18.1 Iodine Flasks, 250-mL with stopper (Note 1).18.2 Water Bath, maintained at 60 6 1C.19. Reagents19.1 Acetic Acid, Glacial.19.2 Carbon Dioxide, cylinder.19.3 Sodium Iodide, Saturated SolutionSee 9.4.19.4 Sodium Thiosulfate, Standard Solution (0.1 meq/mL(N)See 9.5.19.5 Starch Indicator Solut

42、ionSee 9.6.19.6 Water, De-aeratedSee 9.7.20. Procedure20.1 Add 20 mL of acetic acid to a 250-mL iodine flask andsparge with a rapid flow of carbon dioxide (CO2) for 2 min.Stopper the flask and reserve for the sample.20.2 Accurately weigh a sample containing 3 to 4 meq ofactive oxygen to the nearest

43、0.1 mg and transfer to the flask(Note 2).20.3 Add 5 mL of freshly prepared saturated NaI solution(Note 5). Restopper tightly and swirl. Place a few millilitres ofwater in the well of the flask and allow the flask to standpartially submerged in a water bath maintained at 60C for 1 h.NOTE 5Some peroxi

44、des may require the addition of a small amount ofhydrochloric acid (HCl) to react completely in a reasonable time. In thiscase 1 mL of concentrated HCl shall be added to the solution just beforeit is placed in the water bath.20.4 Remove the flask from the bath and cool to roomtemperature.20.5 Add 60

45、 mL of de-aerated water and titrate with 0.1meq/mL (N)Na2S2O3solution until the solution is a pale strawcolor. Add 1 to 2 mL of starch solution and continue thetitration to the sharp disappearance of the blue color. Recordthe number of millilitres required for titration.20.6 Subtract the number of m

46、illilitres required for titrationof a blank carried through the entire procedure and calculatethe assay value of the sample.NOTE 6The blank titration should normally require about 0.10 mL of0.1 meq/mL (N)Na2S2O3solution. The results should be discarded andthe analysis repeated if high blank values a

47、re obtained.21. Calculation21.1 Calculate the assay as follows:Assay, as percent compound (5)5 A 2 B! 3 N 3 M 3100/W 32C 31000where:A =mLofNa2S2O3solution required for titration of thesample,E298 17a3B =mLofNa2S2O3solution required for titration of theblank,N = meq/mL (N) of the Na2S2O3solution,C =

48、number of peroxide groups in the molecule,M = molecular weight of the compound, andW = grams of sample used.21.2 Calculate the percent of active oxygen in the com-pound as follows:Active oxygen, % 5 A 2 B! 3 N 30.008/W 3100 (6)21.3 If required, the percent active oxygen can be convertedto a specific

49、 peroxide using the appropriate conversion factor.See 11.3.22. Report22.1 Report the assay value of the compound to the nearest0.01 %.23. Precision and Bias523.1 The following criteria should be used in judging theacceptability of results (Note 7):23.1.1 Repeatability (Single Analyst)The standard devia-tion for a single determination has been estimated to be0.080 % absolute at 24 df. The 95 % limit for the differencebetween two such determinations is 0.23 % absolute.23.1.2 Laboratory Precision (Within-Laboratory, Between-Days Varia