1、Designation: E298 17E298 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 parent
2、heses 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 Temp
3、erature 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 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, and safetyprecautions.1.3 The value
4、s stated in SI units are to be regarded as standard. The values given in parentheses are for information only.1.4 This standard does not purport 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 safet
5、y and health practices and determine the applicability of regulatorylimitations prior to use.1.4 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, and safetyprecautions.1.5 This international standard was developed in accordance with inte
6、rnationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193
7、Specification for Reagent WaterD6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E200 Practice for
8、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 provideprocedures for assaying organic peroxides to determine if they
9、 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 Committee on Analytical Reagents of the American Chemical Society
10、, 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.1 These test methods are under the jurisdiction of ASTM Committee D16 on Aromatic
11、 Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and are thedirect responsibility of Subcommittee D16.15 on Industrial and Specialty General Standards.Current edition approved Feb. 1, 2017July 1, 2017. Published February 2017July 2017. Originally approved in 1966. Last previous ed
12、ition approved in 20082017 asE298 08.E298 17. DOI: 10.1520/E0298-17.10.1520/E0298-17a.2 For referencedASTM standards, visit 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
13、page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Socie
14、ty, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, 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
15、indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately 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
16、be considered the official document.*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 States14.2 Unless otherwise indicated, references to water shall be understood to mean Type
17、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 peroxides.Dialkyl peroxides do not react, while peresters and bridge-
18、type peroxides like ascaridole react slowly and incompletely.5.2 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 Acid PeroxideSuccinic acid peroxid
19、e.5.2.3 Ketone PeroxidesCyclohexanone peroxide and methyl ethyl ketone peroxide.5.2.4 Alkyl Hydroperoxidestert-Butylhydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide.5.1 This test method covers the assay of organic peroxides that are easily reduced, such as hydroperoxides and diacyl peroxides
20、.Dialkyl peroxides do not react, while peresters and bridge-type peroxides like ascaridole react slowly and incompletely.5.2 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 decanoy
21、l peroxides.5.2.2 Dibasic Acid 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
22、methylene chloride and acetic 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 absor
23、bing iodine.8. Apparatus8.1 Iodine 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
24、) in de-aerated water. This solutionshould 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.
25、6 Starch Indicator Solution (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
26、flow of CO2 for 2 min. Stopper 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 2T
27、he approximate weight of the sample to be used in the analysis may be calculated as follows:Sample weight,g53.5M/2C 31000 (1)E298 17a2where: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 diss
28、olve the sample.10.4 Add 5 mL of freshly 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 un
29、til 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 number ofmillilitres required for titration.10.6 Subtract the number of millilitres required for titration of a blank carried through the entire
30、 procedure and calculate theassay value 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.11. Calculation11.1 Calculate the assay as follows:As
31、say,as percent compound5A 2B!3N 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
32、 compound, andW = grams of sample 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 i
33、n Peroxide X 3F (4)where:F = conversion 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 nea
34、rest 0.01 %.13. Precision 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 b
35、etween 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 on different days, has been estimated to be 0.010 % absolute at 18 df.The 95 %limi
36、t for the difference between 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 differ
37、ence between twosuch averages 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 laboratories5 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Researc
38、h Report RR:E15-1001. Contact ASTM CustomerService at serviceastm.org.E298 17a3performed duplicate determinations and repeated them on a second day, for a total of 72 determinations. Practice E180 was used in developing thesestatements.13.2 BiasThe bias of this test method has not been determined du
39、e to the lack of suitable reference materials or methodology.14. Quality Guidelines14.1 Laboratories shall have a quality control system in place.14.1.1 Confirm the performance of the test instrument or test method by analyzing a quality control sample following theguidelines of standard statistical
40、 quality control practices.14.1.2 Aquality control sample is a stable material isolated from the production process and representative of the sample beinganalyzed.14.1.3 When QA/QC protocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity
41、 of test results.14.1.4 When there are no QA/QC protocols established in the testing facility, use the guidelines described in Guide D6809 orsimilar statistical quality control practices.SODIUM IODIDE, 60C TEST METHOD14. Scope14.1 This test method covers the assay of organic peroxides that are moder
42、ately stable, such as peresters, di-acyl 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-buty
43、lperoxyisobutyrate, di-t-butyl diperphthalate, t-butyl perbenzoate, and 2,2-bis(t-butylperoxy) butane.15. Scope15.1 This test method covers the assay of organic peroxides that are moderately stable, such as peresters, di-acyl peroxides, andn-alkyl peroxides. These peroxides react slowly with sodium
44、iodide at room temperature, but do not require the use of hydroiodicacid.15.2 Specific peroxides that can be analyzed by this procedure include the following: t-butyl peracetate, t-butylperoxyisobutyrate, di-t-butyl diperphthalate, t-butyl perbenzoate, and 2,2-bis(t-butylperoxy) butane.16. Summary o
45、f Test Method16.1 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 thiosulfate solution.17. Interferences17.1 Conjugated diolefins interfere under the
46、conditions of analysis by absorbing iodine.18. Apparatus18.1 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
47、 (0.1 meq/mL (N)See 9.5.19.5 Starch Indicator SolutionSee 9.6.19.6 Water, De-aeratedSee 9.7.20. Procedure20.1 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.20.2 Accurately weigh a sample con
48、taining 3 to 4 meq of active oxygen to the nearest 0.1 mg and transfer to the flask (Note2).E298 17a420.3 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 submerg
49、ed 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.20.4 Remove the flask from the bath and cool to room temperature.20.5 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
