1、Designation: E 1784 97 (Reapproved 2002)Standard Test Method forTotal Peroxides in Acrylonitrile1This standard is issued under the fixed designation E 1784; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe total peroxide content of acrylonitrile in the range of 0.1 to0.6 mg H2O2
3、/kg acrylonitrile (ppm). Peroxides are an undesir-able impurity in acrylonitrile.1.2 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 health practices and de
4、termine the applica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 7.1.3 Review the current Material Safety Data Sheets (MSDS)for detailed information concerning toxicity, first aid proce-dures, and safety precautions.2. Referenced Documents2.1 ASTM Sta
5、ndards:D 1193 Specification for Reagent Water2E 60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption Spectrometry3E 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial Chemicals4E 200 Practice for Preparation, Standardiza
6、tion, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis43. Summary of Test Method3.1 Peroxides in the sample react with potassium iodide toform the yellow I3ion. The intensity of the color, which isproportional to the concentration of the I3ion, is measured at365 nm. Results are ex
7、pressed as total peroxides as H2O2.4. Significance and Use4.1 This test method provides for the determination of totalperoxide in acrylonitrile in the range of 0.1 to 0.6 ppm. Onlyperoxides or other oxidants that react under the conditions ofthis test method are measured.5. Apparatus5.1 Spectrophoto
8、meter, capable of measuring at 365 nm,5.2 Absorption Cells, 1-cm, borosilicate, matched, and5.3 Buret, 25-mL capacity.NOTE 1Photometers and photometric practice described in this testmethod shall conform to Practice E 60.6. Reagents6.1 Purity of ReagentsUnless otherwise indicated, allreagents shall
9、conform to the specifications of the Committeeon Analytical Reagents of the American Chemical Societywhere such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of th
10、e determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water mean Type II or Type III reagent water conforming toSpecification D 1193.6.3 Potassium Iodide.6.4 Acetic Anhydride.6.5 Hydrogen Peroxide, 30 %.6.6 Acrylonitrile, Peroxide FreePrepare by passing acry-lonitrile througha2
11、cm3 40 cm glass column packed with 50mL of activated alumina or acid form ion exchange resin.61This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved Oc
12、t. 10, 2002. Published February 2003. Originallyapproved in 1996. Last previous edition approved in 1997 as E 1784 97.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 03.05.4Annual Book of ASTM Standards, Vol 15.05.5Reagent Chemicals, American Chemical Society Specificat
13、ions, AmericanChemical Society, 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,
14、 Inc. (USPC), Rockville,MD.6Rohm and Haas Amberlyst 15 has been found to be suitable or an equivalentresin may be used.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Flow through the column should be approximately 8 to 10 bedvolumes
15、 per h. The absorbance obtained by following 9.1through 9.3 should be less than 0.01. Alternative means ofpreparation include extraction with 10 % NaOH followed bydistillation. For the extraction technique, extract 100 mL ofacrylonitrile with 50 mL of 10 % NaOH, follow with tripleextraction with wat
16、er. The volume of peroxide free acryloni-trile required for calibration is 500 mL.6.7 Sulfuric Acid Solution, 12 NMeasure 360 mL ofconcentrated sulfuric acid (H2SO4sp gr 1.84) into a 500-mLgraduated cylinder and slowly add it to 400 mL of water in a1000-mL beaker while stirring. Rinse the cylinder w
17、ith waterand add the washings to the beaker with water. Mix theacid-water mixture, allow to cool, and transfer to a 1-Lvolumetric flask. Dilute to volume with water, mix well, andstore in a closed glass container.6.8 Ammonium Molybdate Solution, 3 %Dissolve 1.5 g ofammonium molybdate, (NH4)6Mo7O244H
18、2O in water anddilute to 500 mL. Adjust the pH to 7.0 using 0.01 N NaOH or0.01 N HCl as required.6.9 Sodium Thiosulfate Solution, 0.1 NPrepare and stan-dardize in accordance with Practice E 200.6.10 Starch Indicator Solution, 1 %Prepare in accordancewith Practice E 200.7. Hazards7.1 Acrylonitrile is
19、 potentially hazardous to human health ifnot properly handled. Acrylonitrile is a suspected humancarcinogen. Use acrylonitrile in a well ventilated hood.7.2 Acrylonitrile can contribute to a toxic condition insystems of the human body, from inhalation, swallowing, orcontact with the eyes or skin. Di
20、rect contact with acrylonitrilecan cause skin burns as well.7.3 Acrylonitrile liquid and vapor are readily absorbed intoshoe leather and clothing and will penetrate most rubbers,barrier fabrics, or creams. Contact lenses should not be worn inareas where eye contact with acrylonitrile could occur. Us
21、eimpermeable protective clothing and consult the current MSDSfor recommended materials.8. Standard Solutions and Calibration8.1 Pipet 0.5 mL of 30 % H2O2into a 100-mL volumetricflask, dilute to volume with water, and mix thoroughly. Thisstock peroxide solution contains approximately 0.15 % H2O2.8.2
22、Standardization of the stock peroxide solution should bedone in duplicate along with a reagent blank. Dissolve2gofpotassium iodide in 100 mL of water in each of three 250-mLErlenmeyer flasks. Add 25 mL of 12 N sulfuric acid and 3drops of 3 % ammonium molybdate solution to each and swirlto mix. The a
23、mmonium molybdate solution is added tocatalyze the reaction.78.3 Pipet 25 mL of the stock peroxide solution, as describedin 8.1, into two of the flasks, pipet 25 mL of water into the flaskused as the blank, stopper the flasks, and swirl to mix.8.4 Allow to stand for 5 min, then titrate the liberated
24、 iodinewith standard 0.1 N sodium thiosulfate until the color becomespale yellow. Add 1 to 2 mL of starch indicator and continue thetitration to the sharp disappearance of the blue color.8.5 Correct the titer for a blank titration carried through theentire procedure and calculate the exact H2O2conce
25、ntration ofthe stock peroxide solution. The solution should contain about1500 mg H2O2/L of H2O2.mg/L of H2O25V 3 N 3 17.08 3 1000S(1)where:V = average volume sodium thiosulfate required forstandardization, mL,N = exact normality 0.1 N sodium thiosulfate titrant,S = volume peroxide stock solution tak
26、en for standard-ization = 25 mL, and17.08 = mg H2O2/meq.8.6 Pipet 1 mL of the assayed H2O2stock solution into a100-mL volumetric flask containing approximately 50 mL ofacetic anhydride. Dilute to volume with acetic anhydride andmix well. The solution contains approximately 15 mg/L ofH2O2. Calculate
27、the exact concentration.8.7 Pipet 0.5, 1.0, 2.0, and 3.0 mL of the approximately 15mg/L of H2O2solution, as described in 8.6, into respective100-mL volumetric flasks. Dilute each to volume withperoxide-free acrylonitrile and mix well. These standardscontain approximately 0.07, 0.15, 0.30, and 0.45 m
28、g/L ofH2O2. Calculate the actual concentrations, C, of H2O2in AN inppm (w/w) as mg H2O2/kg AN as follows:C 5mg/L of H2O20.806 g/mL3L1000 mL31000 gkg(2)where:0.806 g/mL = density of acrylonitrile.For a 0.30 mg/L of H2O2solution,C 50.30 mg/L of H2O20.806 g/mL50.37 mg H2O2kg AN(3)8.8 Pipet 5 mL of acet
29、ic anhydride into each of five 125-mLglass stoppered Erlenmeyer flasks. Add 0.5 g of potassiumiodide to each. Pipet 25 mL of each of the four standards intothe flasks. Pipet 25 mL of peroxide-free acrylonitrile into thefifth flask to serve as a blank. Stopper the flasks and swirl todissolve the pota
30、ssium iodide.8.9 Allow the flasks to stand for 20 6 1 min, then measurethe absorbance of each solution at 365 nm using 1-cm cells andthe blank as a reference.NOTE 2Protect from light by covering the flasks with aluminum foilor by using tinted glassware as described in 8.8.8.10 Prepare a calibration
31、curve by plotting the absorbanceof each standard versus mg H2O2/kg AN.9. Procedure9.1 Pipet 5 mL of acetic anhydride into each of two 125-mLglass stoppered Erlenmeyer flasks. Add 0.5 g of potassiumiodide.7Standard Methods of Chemical Analysis, Wilfred W. Scott, Sc. D., 5th ed., D.Van Nostrand Co., I
32、nc., New York, NY, 1939, p. 2180.E 1784 97 (2002)29.2 Pipet 25 mL of the acrylonitrile sample into one of theflasks. Pipet 25 mL of peroxide-free acrylonitrile into thesecond flask to serve as a blank. Stopper the flasks and swirl tomix.NOTE 3Protect from light by covering the flasks with aluminum f
33、oilor by using tinted glassware as described in 9.1.9.3 Allow to stand for 20 6 1 min, then measure theabsorbance of the acrylonitrile sample solution at 365 nmunder using 1-cm cells and the blank as a reference.9.4 Determine the peroxide concentration of the sample, asmg H2O2/kg AN, by reference to
34、 the calibration curve.10. Report10.1 Report the concentration of total peroxides as H2O2tothe nearest 0.01 mg H2O2/kg AN (ppm).11. Precision and Bias11.1 Use the following criteria for judging the acceptabilityof results (see Note 4):11.1.1 Repeatability (Single Analyst)The standard devia-tion for
35、a single determination has been estimated to be 0.0108ppm absolute at 12 DF. The 95 % limit for the differencebetween two such runs is 0.03 ppm, absolute.11.1.2 Laboratory Precision (Within-Laboratory, Between-Days Variability), formerly called repeatabilityThe standarddeviation of results (each the
36、 average of duplicates) obtainedby the same analyst on different days, has been estimated to be0.0110 ppm absolute at 6 DF. The 95 % limit for the differencebetween two such averages is 0.03 absolute.11.1.3 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of dupl
37、icates) obtained byanalysts in different laboratories, has been estimated to be0.0373 ppm absolute at 5 DF. The 95 % limit for the differencebetween two such averages is 0.10 ppm absolute.NOTE 4These precision estimates are based on an interlaboratorystudy of analyses performed in 1987 on one sample
38、 of acrylonitrilecontaining an average of 0.098 ppm peroxide. One analyst in each ofseven laboratories performed duplicate determinations and repeated themone day later, for a total of 28 determinations. Data from one laboratorywas omitted.8Practice E 180 was used in developing these precisionestima
39、tes.11.2 BiasThe bias of this test method has not beendetermined because of the lack of acceptable reference mate-rial.12. Keywords12.1 absorbance; acrylonitrile; colorimeter; peroxide; spec-trophotometerASTM International takes no position respecting the validity of any patent rights asserted in co
40、nnection 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.This standard is subject to revision at any time by the respo
41、nsible 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 International Headquarters. Your comments will receive careful
42、 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 below.This standard is copyrighted by ASTM International,
43、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).8Details of the interlaboratory study are available from ASTM InternationalHeadquarters. Request RR: E15 - 1048.E 1784 97 (2002)3
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