1、Designation: D1492 081Standard Test Method forBromine Index of Aromatic Hydrocarbons by CoulometricTitration1This standard is issued under the fixed designation D1492; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEMercury warning was editorially added in March 2010.1. Scope*1.1 This test method covers the determination of the amountof bromi
3、ne-reactive material in aromatic hydrocarbons. It isusually applied to materials having bromine indexes below500.NOTE 1Other test methods for determining bromine-reactive materialare Test Methods D1159, D1491, D2710, and D5776.1.2 This test method has been found applicable to aromatichydrocarbons co
4、ntaining no more than trace amounts of olefinsand that are substantially free from material lighter thanisobutane and have a distillation end point under 288C.1.3 The following applies to all specified limits in this testmethod: For purposes of determining conformance with thistest method, an observ
5、ed value or a calculated value shall berounded off “to the nearest unit” in the last right-hand digitused in expressing the specification limit, in accordance withthe rounding-off method of Practice E29.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement ar
6、e included in thisstandard.1.5 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system, kidney, and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling me
7、rcury andmercury-containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAs website(http:/www.epa.gov/mercury/faq.htm) for additional informa-tion. Users should be aware that selling mercury or mercury-containing products, or both, in your state may be pr
8、ohibited bystate law.1.6 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 determine the applica-bility of regulatory limitations prior t
9、o use. For a specifichazard statement see Section 8.2. Referenced Documents2.1 ASTM Standards:2D891 Test Methods for Specific Gravity, Apparent, ofLiquid Industrial ChemicalsD1159 Test Method for Bromine Numbers of PetroleumDistillates and Commercial Aliphatic Olefins by Electro-metric TitrationD119
10、3 Specification for Reagent WaterD1491 Test Method for Bromine Index of Aromatic Hydro-carbons by Potentiometric Titration3D2710 Test Method for Bromine Index of Petroleum Hy-drocarbons by Electrometric TitrationD3437 Practice for Sampling and Handling Liquid CyclicProductsD3505 Test Method for Dens
11、ity or Relative Density of PureLiquid ChemicalsD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD5776 Test Method for Bromine Index of Aromatic Hydro-carbons by Electrometric TitrationD6809 Guide for Quality Control and Quality AssuranceProcedures fo
12、r Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Other Document:1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct respons
13、ibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 1957. Last previous edition approved in 2007 as D1492 07. DOI:10.1520/D1492-08.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact AS
14、TM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes section appears at the en
15、d of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120043. Terminology3.1 Definition:3.1.1 bromine index (B), nthe number of milligrams (mg)of bromine consumed by 1
16、00 g of sample under givenconditions (mg-Br/100 g).4. Summary of Test Method4.1 The specimen is added to a solvent and titrated withelectrolytically generated bromine at room temperature. Theend point is determined by a dead-stop method. The time oftitration is proportional to the bromine added to t
17、he specimen.5. Significance and Use5.1 This test method is useful for setting specification, foruse as an internal quality control tool, and for use in develop-ment or research work on industrial aromatic hydrocarbons andrelated materials. This test method gives a broad indication ofolefinic content
18、. It will not differentiate between the types ofaliphatic unsaturation.6. Apparatus6.1 Amperometric-Coulometric Apparatus, automatic, suit-able for bromine index titrations with variable generatorcurrent and timer. A typical circuit diagram of suitable equip-ment is shown in Fig. 1.6.2 Syringe, 2 mL
19、 with needle and rubber cap seal.6.3 Stirrer, magnetic.7. Reagents7.1 Purity of ReagentReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical
20、Society,where 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 the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be un
21、derstood to mean reagent water conformingto Type IV of Specification D1193.4Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.5Reagent Chemicals, American Chemical Society Specifications,
22、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, Inc.
23、 (USPC), Rockville,MD.FIG. 1 Automatic Amperometric-Coulometric Titrator CircuitD1492 08127.3 Electrolyte:7.3.1 With Mercury II AcetateTo make 1 L, mix 600 mLof glacial acetic acid, 260 mL of absolute methanol, and 140mL of KBr solution (119 g/L). Dissolve2gofMercury IIacetate in this mixture.7.3.2
24、Without Mercury II AcetateTo make 1 L, mix 600mL of glacial acetic acid, 260 mL of absolute methanol, and140 mL of KBr solution (119 g/L).7.4 Potassium Bromide Solution (119 g/L)Dissolve 119 gof potassium bromide (KBr) in water and dilute to 1 L.8. Hazards8.1 Consult current OSHA regulations, suppli
25、ers MaterialSafety Data Sheets, and local regulations for all materials usedin this test method.9. Sampling9.1 Sample the material in accordance with Practice D3437.10. Procedure10.1 Place 125 mL of electrolyte in a clean, dry titrationcell, insert the electrodes, and begin stirring. Verify the volu
26、meof electrolyte is sufficient to ensure the electrodes are com-pletely submerged and if necessary, increase the volume ofelectrolyte required. Apply the generation current in accor-dance with Table 1.10.2 Before introducing the specimen and immediatelybefore each determination, bring the coulometer
27、 to equilib-rium.10.3 Draw into the syringe the amount of sample prescribedin Table 1 corresponding to the estimated bromine index. Wipethe needle with a clean cloth, attach a rubber cap seal to theneedle, and weigh on the analytical balance. Remove the seal,add the specimen to the electrolyte, and
28、set the timer to zero.Replace the seal, reweigh the syringe, and calculate thespecimen weight.NOTE 2If the density or specific gravity of the specimen is known(Test Methods D891, D3505,orD4052 can be used), the specimen can beadded by means of a pipet or microburet and the weight calculated.10.4 Beg
29、in titration of the specimen. As the titration pro-ceeds, keep the generation current at the selected value. Thegeneration of bromine will continue as long as it is consumedby the sample. At the end point an incremental increase inbromine concentration causes the titration and timer to stopautomatic
30、ally. Forty seconds after the titration has shut off,continue the titration. If the titration cuts off, immediately, theend point has been reached and the titration may be consideredcomplete. Otherwise, it may be necessary to continue thetitration in steps, waiting about 40 s between steps, until th
31、etitration time increment is4sorless. Note the total titrationtime and generation current.11. Calculation11.1 Calculate the bromine index, B (mg-Br/100 g),asfollows:B 5T 3 I 3 79.9965W(1)where:T = titration time, sI = generation current, mAW = weight of specimen, g79.9 = MW bromine (grams/mole), and
32、965 = Faradays constant (96 500 coulomb/mole)/10012. Report12.1 Report the following information:12.1.1 Report bromine index to the nearest unit.13. Precision and Bias13.1 With Mercury II Acetate:13.1.1 Precision data were generated using titrators fromCentral Scientific Co. The precision obtained u
33、sing titratorsfrom other suppliers has not been determined.13.1.2 PrecisionThe following data should be used forjudging the acceptability of results (95 % probability) forbromine indexes from 0 to 50:13.1.2.1 Intermediate Precision (formerly calledRepeatability)The standard deviation is 0.39. Duplic
34、ateresults by the same operator should be considered suspect ifresults differ by more than 1.15.NOTE 3Number of data used, 91; number of degrees of freedom, 61;number of cooperating laboratories, 4.13.1.3 ReproducibilityThe standard deviation is 1.43. Theresults submitted by two laboratories should
35、be consideredsuspect if they differ by more than 4.1.13.2 Without Mercury II Acetate:13.2.1 PrecisionA ruggedness study was performed byanalyzing three samples 20 times and one sample 5 times eachover the shortest practical time. The calculated repeatability isshown in Table 2.13.2.2 RepeatabilitySe
36、e Table 2.13.2.3 ReproducibilityTo be determined.14. Quality Guidelines14.1 Refer to Guide D6809 for suggested QA/QC activitiesthat can be used as a part of this test method. It is recom-mended that the operator of this test method select and performTABLE 1 Specimen Size and Generation CurrentEstima
37、tedBromine IndexSpecimen Weight,gGenerationCurrent, mA0 to 20 1.000 1.020 to 200 0.600 5.0200 to 2000 0.060 5.0TABLE 2 RepeatabilityASample Name Replicates (n)Conc. mg-Br/100 gr997.5 mg-Br/100g Std 20 1012 39.1Toluene-Pit EPX 20 31.2 2.9Xylene-Plant Feed 20 10.7 2.3Reformate-Feed 5 670 53.9ARepeatab
38、ility = SD * 2.8.D1492 0813relevant QA/QC activities like the ones in Guide D6809 to helpensure the quality of data generated by this test method.15. Keywords15.1 aromatic hydrocarbons; bromine index; bromine-reactive; coulometric titration; titrationSUMMARY OF CHANGESCommittee D16.07 has identified
39、 the location of selected changes to this standard since the last issue(D1492 - 07) that may impact the use of this standard. (Approved July 1, 2008.)(1) Updated 7.3, Electrolyte, to include the use of cell elec-trolyte with and without Mercury II Acetate.(2) Updated Section 13, Precision and Bias,
40、to reflect therepeatability with the use of cell electrolyte with and withoutMercury II Acetate.(3) Added in 13.2.1, Precision, Table 2 which summarizes therepeatability using cell electrolyte without Mercury II Acetate.(4) Updated 13.2, Precision and Bias, to follow CommitteeD16 Guidelines.Subcommi
41、ttee D16.07 has identified the location of selected changes to this standard since the last issue(D6809 - 02) that may impact the use of this standard. (Approved February 1, 2007.)(1) Updated 2.1 to add reference to Guide D6809.(2) Updated footnotes for 2.1 and 2.2 as specified in D16Editorial Guide
42、lines for Preparation and Revision of Standards.(3) Modified 3.1.1 to further clarify the definition of bromineindex (B) by adding the weight and concentration units mgand mg-br/100 g.(4) Modified 11.1 by adding the units mg-Br/100 g and theunit definition of constants used in the calculation of bro
43、mineindex.(5) Added Section 13.2.1 on QA/QC referencing Guide D6809specified in D16 Editorial Guidelines for Preparation andRevision of Standards.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of
44、 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 responsible technical committee and must be reviewed every five
45、 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 consideration at a meeting of theresponsible technical co
46、mmittee, 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, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
47、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 ASTM website (www.astm.org/COPYRIGHT/).D1492 0814
