ASTM_D_5776_-_14a.pdf

Designation:D577614aStandard Test Method forBromine Index of Aromatic Hydrocarbons by ElectrometricTitration1This standard is issued under the fixed designation D5776;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 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 determines the amount of bromine-reactive material in aromatic hydrocarbons and is thus ameasure of trace amounts of unsaturates in these materials.It isapplicable to materials having bromine indexes below 35.Materials with a higher bromine index can be analyzed by thismethod;however,the precision section does not apply.1.2 This test method is applicable to aromatic hydrocarbonscontaining no more than trace amounts of olefins and that aresubstantially free from material lighter than isobutane and havea distillation end point under 288C.1.3 In determining the conformance of the test results usingthis method to applicable specifications,results shall berounded off in accordance with the rounding-off method ofPractice E29.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 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 to use.For a specifichazard statement see Section 8.2.Referenced Documents2.1 ASTM Standards:2D1159 Test Method for Bromine Numbers of PetroleumDistillates and Commercial Aliphatic Olefins by Electro-metric TitrationD1193 Specification for Reagent WaterD3437 Practice for Sampling and Handling Liquid CyclicProductsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Document:OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.120033.Terminology3.1 Definitions:3.1.1 bromine index,nthe number of milligrams of bro-mine consumed by 100 g of sample under given conditions.4.Summary of Test Method4.1 The specimen dissolved in a specified solvent is titratedwith standard bromide-bromate solution.The end point isindicated by a fixed end-point electrometric titration apparatus,when the presence of free bromine causes a sudden change inthe polarization voltage of the system.5.Significance and Use5.1 This test method is suitable for setting specification,foruse as an internal quality control tool,and for use in develop-ment or research work on industrial aromatic hydrocarbons andrelated material.This test method gives a broad indication ofolefinic content.It does not differentiate between the types ofaliphatic unsaturation.6.Apparatus6.1 Fixed End Point Electrometric Titration ApparatusAny fixed end-point apparatus may be used incorporating ahigh resistance polarizing current supply capable of maintain-ing approximately 1 to 50 A across two platinum plate1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved July 1,2014.Published August 2014.Originallyapproved in 1995.Last previous edition approved in 2014 as D5776 14.DOI:10.1520/D5776-14A.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available 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.*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 States1 electrodes or a combination platinum electrode and with asensitivity such that a voltage change of approximately 500mV at these electrodes is sufficient to indicate the end point(see Note 1).NOTE1The reagents and techniques may be checked by determiningthe bromine index of a 100 mg/kg cyclohexene in heptane.This isexpected to give a bromine index of 18 to 20 mg/100 g sample.Refer toTest Method D1159 for a list of expected bromine indexes of variouscompounds.6.2 Titration VesselA tall form glass beaker of approxi-mately 250-mL capacity or a water jacketed titration vessel ofapproximately 250-mL capacity connected to a refrigeratedcirculating water bath controlling the temperature at 0 to 5C.Apair of platinum electrodes spaced not