1、Designation: E1228 09E1228 17Standard Test Method forAssay of Peroxy EstersCatalyzed Iodometric Procedure1This standard is issued under the fixed designation E1228; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. 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 assay of organic peroxides of the peroxy ester type.NOTE 1Other test methods for the assay of o
3、rganic peroxides are given in Test Methods E298, E475, and E755.1.2 Review the current material safety data sheets (MSDS)(SDS) for detailed information concerning toxicity, first aidprocedures, and safety precautions.1.3 The values stated in SI units are to be regarded as the standard. No other unit
4、s of measurement are included in this testmethod.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 safety and health practices and determine the applicability of reg
5、ulatorylimitations prior to use. Specific hazards statements are given in Section 9.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guide
6、s and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related MaterialsE180
7、 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical AnalysisE298 Test Methods for Assay of Organic PeroxidesE4
8、75 Test Method for Assay of Di-tert-Butyl Peroxide Using Gas ChromatographyE755 Test Method for Dicumyl Peroxide, Assay (Liquid Chromatography) (Withdrawn 2016)33. Terminology3.1 Definitions:3.1.1 active oxygenthe oxidizing power present in organic peroxides expressed as oxygen (equivalent weight 8.
9、00).4. Summary of Test Method4.1 A sample is dissolved in a mixture of isopropyl alcohol, acetic acid, and cupric chloride. A solution of potassium iodide isadded and the mixture is briefly heated, then allowed to react in the dark at room temperature for 30 min. The cupric ion catalyzesthe reductio
10、n of the peroxide and the liberated iodine is titrated with standard sodium thiosulfate solution.5. Significance and Use5.1 Peroxy esters are widely used as chemical intermediates, catalysts, and initiators. This test method provides a procedure forassaying peroxy esters to determine if they are sui
11、table for their intended use.1 This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the directresponsibility of Subcommittee D16.15 on Industrial and Specialty General Standards.Current edition approved
12、 April 1, 2009June 1, 2017. Published April 2009July 2017. Originally approved in 1988. Last previous edition approved in 20032009 asE1228 94 (2003)E1228 09.1. DOI: 10.1520/E1228-09.10.1520/E1228-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service
13、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.This document is not an ASTM standard and is intended only to provide the us
14、er of an ASTM standard an 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 a
15、s published by ASTM is to 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 States16. Interferences6.1 Conjugated diolefins interfere under th
16、e conditions of analysis by absorbing iodine.7. Apparatus7.1 Iodine Flasks, 250-mL capacity, with stoppers.NOTE 2All glassware should be cleaned thoroughly with dichromate cleaning solution before use.7.2 Beakers, 1-mL capacity, glass or PTFE.7.3 Buret, 50-mL capacity, graduated in 0.1-mL subdivisio
17、ns.7.4 Water Bath, maintained at 60C.8. Reagents8.1 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, wheresuc
18、h 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.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to m
19、ean Type II or III reagent waterconforming to Specification D1193.8.3 Acetic Acid, glacial.8.4 Isopropyl Alcohol.8.5 Hydrochloric Acid, (1:100)Dilute 1.0 mL of concentrated hydrochloric acid (HCl) to 100 mL with water.8.6 Cupric Chloride Solution, 1 %Dilute 1.0 g of anhydrous cupric chloride (CuCl2)
20、 to 100 mL with water. Add 1.0 mL of1:100 HCl and mix. The solution should be clear.8.7 Potassium Iodide Solution, 50 %Dissolve 25 g of potassium iodide (KI) in 25 mLof de-aerated water. This reagent shouldbe freshly prepared just prior to use.8.8 Sodium Thiosulfate Standard Solution, (0.1 meq/mL)Pr
21、epare and standardize in accordance with the appropriate sectionsof Practice E200.8.9 Nitrogen Gas, oxygen-free.9. Hazards9.1 Organic peroxides are strong oxidizing agents and present potential fire and explosion hazards.Avoid contact with reducingagents and sources of heat, sparks, or open flames.
22、Reactivity varies widely and some compounds may explode when shocked.Organic peroxides are irritating to the skin, eyes, and mucous membranes. Avoid bodily contact and handle only in awell-ventilated area.10. Procedure10.1 Add 50 mL of isopropyl alcohol and 15 mL of acetic acid to a 250-mL iodine fl
23、ask. A graduate can be used for theseadditions.10.2 Pipet 1.00 mL of 1 % cupric chloride solution into the flask. (WarningThe quantity of the cupric chloride catalystsolution must be carefully measured in order to obtain reproducible results as the reagent also reacts with iodide to liberate iodinea
24、ccording to the following Eq 1:2Cu1114I 22CuI1I2 (1)The blank titration should be approximately 1.0 mL. The results should be discarded and the analysis repeated if a significantly higher blank value isobtained.)10.3 Sparge the solution with a rapid flow of nitrogen for 2 min, then stopper the flask
25、 and reserve.10.4 Accurately weigh a sample containing 3 to 4 meq of active oxygen in a 1-mL beaker. Transfer the beaker containing thesample to the prepared flask and immediately restopper and mix. The approximate sample weight may be calculated as follows:Sample mass,g5 3.5 M2C 31000 (2)4 Reagent
26、Chemicals, 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
27、NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.E1228 172where:M = molecular weight of compound, andC = number of peroxide groups in the molecule.NOTE 3Volatile liquid peroxides may be diluted to a known volume with isopropyl alcohol and aliquots taken for analysis.10.5
28、While maintaining a flow of nitrogen over the solution, add 5 mL(graduate) of freshly prepared 50 % KI solution, and thenimmediately restopper and swirl to mix.10.6 Place the flask in a water bath maintained at 60C for 20 s while gently swirling. The level of water in the bath shouldbe above the lev
29、el of solution in the flask.NOTE 4The reaction is temperature sensitive. If the temperature of the solution is above 25C, a 30-min reaction time is generally sufficient for mostperesters. If the temperature of the solution is less than 25C, a longer reaction period may be required. By preheating the
30、 solution for 20 s at 60C, thesolution temperature is high enough to obtain complete reaction in 30 min with minor variation in the ambient laboratory temperature.10.7 Remove the flask from the bath and allow to stand in a dark location at room temperature for 30 min.10.8 Add 50-mL of de-aerated wat
31、er and titrate the solution with 0.1 meq/mL Na2S2O3 solution to the colorless end point.Record the number of millilitres required for the sample titration.10.9 Subtract the number of millilitres required for titration of a blank carried simultaneously through the entire procedure andcalculate the as
32、say value of the sample. (See Warning note in 10.2.)11. Calculation11.1 Calculate the assay as follows:assay,as %compound5 (3)A 2B! 3N 3M 3100#/W 32C 31000!where:A = Na2S2O3 solution required for titration of the sample, mL,B = Na2S2O3 solution required for titration of the blank, mL,N = meq/mL, nor
33、mality of the Na2S2O3 solution,C = number of peroxide groups in the molecule,M = molecular weight of the ground, andW = sample used, g.11.2 Calculate the percent of active oxygen in the compound as follows:active oxygen,%5A 2B! 3N 30.008#3100W (4)NOTE 5This assay is based on the determination of act
34、ive oxygen under specified conditions. If other organic peroxides are present as impurities andrelease equivalent amounts of active oxygen under the same conditions, their concentrations must be determined by appropriate HPLC or GC proceduresand the results corrected accordingly.12. Report12.1 Repor
35、t the assay value of the compound to the nearest 0.1 %.13. Precision and Bias513.1 PrecisionThe following criteria should be used for judging the acceptability of results: (see Note 6).13.1.1 Repeatability (Single Analyst)The standard deviation for a single determination has been estimated to be 0.1
36、35 % at14 DF. The 95 % limit for the difference between two such runs is 0.4 %.13.1.2 Laboratory PrecisionThe standard deviation of results (each the average of duplicates), obtained by the same analyston different days, has been estimated to be 0.141 % absolute at 6 DF. The 95 % limit for the diffe
37、rence between two such averagesis 0.4 % 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 0.236 % absolute at 3 DF. The 95 % limit for the difference betweentwo
38、such averages is 0.7 %.13.2 BiasThe bias of this test method cannot be determined due to the unavailability of suitable reference materials.NOTE 6The above precision estimates are based upon an interlaboratory study performed in 1987 on samples of t-butyl perbenzoate and t-butylperacetate with manuf
39、acturers assays of 98.3 % and 51.0 %, respectively. One analyst in each of four laboratories performed duplicate determinations5 Supporting data are available from ASTM Headquarters. Request have been filed at ASTM International Headquarters and may be obtained by requesting ResearchReport RR:E15-10
40、36. Contact ASTM Customer Service at serviceastm.org.E1228 173and repeated one day later, for a total of 32 determinations. Practice E180 was used in developing these precision estimates.14. Quality Guidelines14.1 Laboratories shall have a quality control system in place.14.1.1 Confirm the performan
41、ce of the test instrument or test method by analyzing a quality control sample following theguidelines of standard statistical 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
42、 QA/QC protocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity 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 contr
43、ol practices.15. Keywords15.1 active oxygen; iodometric; peroxides; peroxyestersSUMMARY OF CHANGESCommittee E15Subcommittee D16.15 has identified the location of selected changes to this standard since thelast issue (E1228 - 94E1228(2003)09)1) that may impact the use of this standard. (April (Approv
44、ed June 1,2009)2017.)(1) Updated units of measure to comply with the International System of Units (SI).Added Section 14 Quality Guidelines.(2) Added paragraph in Scope stating that the SI units are to be considered standard.(3) Added Summary of Changes section.ASTM International takes no position r
45、especting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard 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.Thi
46、s standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif 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 Inter
47、national Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, 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 b
48、elow.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). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 174
