1、Designation: E298 08E298 17Standard 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 parenth
2、eses indicates 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 reduction:1.1.1 Sodium Iodide, Room Tempe
3、rature Test Method, for organic peroxides easy to reduce, and1.1.2 Sodium Iodide, 60C Test Method, for organic peroxides that are moderately stable.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.3 This standard does not pu
4、rport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 Review the current material safety data sh
5、eets (MSDS) Safety Data Sheets (SDS) for detailed information concerningtoxicity, first-aid procedures, and safety precautions.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Indus
6、trial and Specialty Chemicals(Withdrawn 2009)3E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis3. Significance and Use3.1 Organic peroxides are widely used as chemical intermediates, catalysts, and initiators. These test methods provi
7、deprocedures for assaying organic peroxides to determine if they are suitable for their intended use.4. Purity of Reagents4.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the C
8、ommittee on Analytical Reagents of the American Chemical Society, wheresuch specifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.4.2 Unless otherw
9、ise indicated, references to water shall be understood to mean Type II or Type III reagent water conformingto Specification D1193.SODIUM IODIDE, ROOM TEMPERATURE TEST METHOD5. Scope5.1 This test method covers the assay of organic peroxides that are easily reduced, such as hydroperoxides and diacyl p
10、eroxides.Dialkyl peroxides do not react, while peresters and bridge-type peroxides like ascaridole react slowly and incompletely.1 These test methods are under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons and Related Chemicals and are the direct responsibility ofSubcommittee D16.1
11、5 on Industrial and Specialty General Standards.Current edition approved April 1, 2008Feb. 1, 2017. Published May 2008February 2017. Originally approved in 1966. Last previous edition approved in 20012008 asE298 01.E298 08. DOI: 10.1520/E0298-08.10.1520/E0298-17.2 For referencedASTM standards, visit
12、 theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Reagent Ch
13、emicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and Na
14、tionalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately
15、depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM Interna
16、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Specific peroxides that can be analyzed by this procedure include the following:5.2.1 Diacyl PeroxidesBenzoyl 2,4-dichlorobenzoyl,p-chlorobenzoyl, lauroyl, acetyl, and decanoyl peroxides.5.2.2 Dibasic Aci
17、d PeroxideSuccinic acid peroxide.5.2.3 Ketone PeroxidesCyclohexanone peroxide and methyl ethyl ketone peroxide.5.2.4 Alkyl Hydroperoxidestert-Butylhydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide.6. Summary of Test Method6.1 A sample is dissolved in a mixture of methylene chloride and acetic
18、 acid. A saturated solution of sodium iodide is addedand the mixture is allowed to react in the dark at room temperature for 15 min. The liberated iodine is then titrated with standardsodium thiosulfate solution.7. Interferences7.1 Conjugated diolefins interfere by absorbing iodine.8. Apparatus8.1 I
19、odine Flasks, 250-mL, with stoppers.NOTE 1All glassware should be thoroughly cleaned before use.9. Reagents9.1 Acetic Acid, Glacial.9.2 Carbon Dioxide, cylinder.9.3 Methylene Chloride.9.4 Sodium Iodide, Saturated SolutionPrepare a saturated solution of sodium iodide (NaI) in de-aerated water. This s
20、olutionshould be prepared just prior to use and kept in an amber bottle.9.5 Sodium Thiosulfate, Standard Solution (0.1 meq/mL(N)Prepare and standardize a 0.1 meq/mL(N) solution of sodiumthiosulfate (Na2S2O3) in accordance with the appropriate sections of Practice E200.9.6 Starch Indicator Solution (
21、10 g/L), Prepare as described in the appropriate sections of Practice E200.9.7 Water, De-aeratedPass carbon dioxide (CO2) through distilled water for several minutes prior to use.10. Procedure10.1 Add 20 mL of acetic acid to a 250-mL iodine flask and sparge with a rapid flow of CO2 for 2 min. Stoppe
22、r the flask andreserve for the sample.10.2 Accurately weigh a sample containing 3 to 4 meq of active oxygen to the nearest 0.1 mg and transfer to the flask. Volatileliquid peroxides may be diluted to a known volume with acetic acid and aliquots taken for analysis.NOTE 2The approximate weight of the
23、sample to be used in the analysis may be calculated as follows:Sample weight,g53.5M/2C 31000 (1)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. Swirl briefly to dissolve the sample.10.4 Add 5 mL of fresh
24、ly prepared saturated NaI solution. Restopper and swirl. Place a few millilitres of water in the well ofthe flask and allow to stand in the dark at room temperature for 15 min.10.5 Add 50 mL of de-aerated water and titrate with 0.1 meq/mL (N) Na2S2O3 solution until the solution is a pale straw color
25、.Add 1 to 2 mL of starch solution and continue the titration to the sharp disappearance of the blue color. Record the number ofmillilitres required for titration.10.6 Subtract the number of millilitres required for titration of a blank carried through the entire procedure and calculate theassay valu
26、e of the sample.NOTE 3The blank titration should normally require 0.05 mL or less of 0.1 meq/mL (N) Na2S2O3 solution. The results should be discarded and theanalysis repeated if high blank values are obtained.E298 17211. Calculation11.1 Calculate the assay as follows:Assay,as percent compound5A 2B!3
27、N 3M 3100/W 32C 31000 (2)where:A = mL of Na2S2O3 solution required for titration of the sample,B = mL of Na2S2O3 solution required for titration of the blank,N = meq/mL (N) of the Na2S2O3 solution,C = number of peroxide groups in the molecule,M = molecular weight of the compound, andW = grams of sam
28、ple used.11.2 Calculate the percent active oxygen in the compound as follows:Active oxygen,%5A 2B!3N 30.0083100/W (3)11.3 If required, the percent active oxygen can be converted to a specific peroxide using the appropriate conversion factor.Peroxide X,%5%Active Oxygen in Peroxide X 3F (4)where:F = c
29、onversion factor for CompoundX11.3.1 Conversion Factors for some common peroxides are as follows:Cumene Hydroperoxide = 9.5125Benzoyl Peroxide = 15.140t-Butyl Hydroperoxide = 5.6328Lauroyl Peroxide = 24.91512. Report12.1 Report the assay value of the compound to the nearest 0.01%.0.01 %.13. Precisio
30、n and Bias513.1 The following criteria shall be used for judging the acceptability of results (Note 4):13.1.1 Repeatability (Single Analyst)The standard deviation for a single determination has been estimated to be 0.047 %absolute at 36 df. The 95 % limit for the difference between two such determin
31、ations 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 on different days, has been estimated to be 0.010 % absolute at 18 df.The 95 %limit for the difference bet
32、ween two such averages is 0.028 % absolute.13.1.3 Reproducibility (Multilaboratory)The standard deviation of results (each the average of duplicates) obtained byanalysts in different laboratories has been estimated to be 0.035 % absolute at 5 df. The 95 % limit for the difference between twosuch ave
33、rages is 0.10 % absolute.NOTE 4These precision estimates are based on an interlaboratory study in which 3 samples were analyzed. One analyst in each of 6 laboratoriesperformed duplicate determinations and repeated them on a second day, for a total of 72 determinations. Practice E180 was used in deve
34、loping thesestatements.13.2 BiasThe bias of this test method has not been determined due to the lack of suitable reference materials or methodology.SODIUM IODIDE, 60C TEST METHOD14. Scope14.1 This test method covers the assay of organic peroxides that are moderately stable, such as peresters, di-acy
35、l peroxides, andn-alkyl peroxides. These peroxides react slowly with sodium iodide at room temperature, but do not require the use of hydroiodicacid.14.2 Specific peroxides that can be analyzed by this procedure include the following: t-butyl peracetate, t-butylperoxyisobutyrate, di-t-butyl diperpht
36、halate, t-butyl perbenzoate, and 2,2-bis(t-butylperoxy) butane.15. Summary of Test Method15.1 A sample is dissolved in glacial acetic acid. Saturated sodium iodide solution is then added and the mixture is allowed toreact for 1 h at 60C. The liberated iodine is titrated with standard sodium thiosulf
37、ate solution.5 Supporting data are available from ASTM Headquarters. Request have been filed at ASTM International Headquarters and may be obtained by requesting ResearchReport RR:E15-1001. Contact ASTM Customer Service at serviceastm.org.E298 17316. Interferences16.1 Conjugated diolefins interfere
38、under the conditions of analysis by absorbing iodine.17. Apparatus17.1 Iodine Flasks, 250-mL with stopper (Note 1).17.2 Water Bath, maintained at 60 6 1C.18. Reagents18.1 Acetic Acid, Glacial.18.2 Carbon Dioxide, cylinder.18.3 Sodium Iodide, Saturated SolutionSee 9.4.18.4 Sodium Thiosulfate, Standar
39、d Solution (0.1 meq/mL (N)See 9.5.18.5 Starch Indicator SolutionSee 9.6.18.6 Water, De-aeratedSee 9.7.19. Procedure19.1 Add 20 mLof acetic acid to a 250-mLiodine flask and sparge with a rapid flow of carbon dioxide (CO2) for 2 min. Stopperthe flask and reserve for the sample.19.2 Accurately weigh a
40、sample containing 3 to 4 meq of active oxygen to the nearest 0.1 mg and transfer to the flask (Note2).19.3 Add 5 mL of freshly prepared saturated NaI solution (Note 5). Restopper tightly and swirl. Place a few millilitres of waterin the well of the flask and allow the flask to stand partially submer
41、ged in a water bath maintained at 60C for 1 h.NOTE 5Some peroxides may require the addition of a small amount of hydrochloric acid (HCl) to react completely in a reasonable time. In this case1 mL of concentrated HCl shall be added to the solution just before it is placed in the water bath.19.4 Remov
42、e the flask from the bath and cool to room temperature.19.5 Add 60 mL of de-aerated water and titrate with 0.1 meq/mL (N) Na2S2O3 solution until the solution is a pale straw color.Add 1 to 2 mL of starch solution and continue the titration to the sharp disappearance of the blue color. Record the num
43、ber ofmillilitres required for titration.19.6 Subtract the number of millilitres required for titration of a blank carried through the entire procedure and calculate theassay value of the sample.NOTE 6The blank titration should normally require about 0.10 mL of 0.1 meq/mL (N) Na2S2O3 solution. The r
44、esults should be discarded and theanalysis repeated if high blank values are obtained.20. Calculation20.1 Calculate the assay as follows:Assay,as percent compound (5)5A 2B!3N 3M 3100/W 32C 31000where:A = mL of Na2S2O3 solution required for titration of the sample,B = mL of Na2S2O3 solution required
45、for titration of the blank,N = meq/mL (N) of the Na2S2O3 solution,C = number of peroxide groups in the molecule,M = molecular weight of the compound, andW = grams of sample used.20.2 Calculate the percent of active oxygen in the compound as follows:Active oxygen, %5A 2B!3N 30.008/W 3100 (6)20.3 If r
46、equired, the percent active oxygen can be converted to a specific peroxide using the appropriate conversion factor. See11.3.21. Report21.1 Report the assay value of the compound to the nearest 0.01 %.E298 17422. Precision and Bias522.1 The following criteria should be used in judging the acceptabili
47、ty of results (Note 7):22.1.1 Repeatability (Single Analyst)The standard deviation for a single determination has been estimated to be 0.080 %absolute at 24 df. The 95 % limit for the difference between two such determinations is 0.23 % absolute.22.1.2 Laboratory Precision (Within-Laboratory, Betwee
48、n-Days Variability)The standard deviation of results (each theaverage of duplicates) obtained by the same analyst on different days, has been estimated to be 0.055 % absolute at 12 df.The 95 %limit for the difference between two such averages is 0.15 % absolute.22.1.3 Reproducibility (Multilaborator
49、y)The standard deviation of results (each the average of duplicates) obtained byanalysts in different laboratories has been estimated to be 0.126 % absolute at 5 df. The 95 % limit for the difference between twosuch averages is 0.35 % absolute.NOTE 7These precision estimates are based on an interlaboratory study conducted in which 2 samples were analyzed. One analyst in each of 6laboratories performed duplicate determinations and repeated them on a second day, for a total of 48 determinations. Practice E180 was used in developingthese st
