ASTM_D_8411_-_21.pdf

Designation:D841121Standard Test Method forRubber Compounding MaterialsDetermination of2-Mercaptobenzothiazole(MBT)in Rubber1This standard is issued under the fixed designation D8411;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.Scope1.1 This standard test method covers a procedure for thedetermination of extractable 2-Mercaptobenzothiazole(MBT)in rubber by high performance liquid chromatography(HPLC)to assess its bioavailability.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1991 TestMethodforRubberChemicals2-Mercaptobenzothiazole(MBT)AssayD5044 Test Method for Rubber Compounding MaterialsFree 2-Mercaptobenzothiazole(MBT)in BenzothiazylDisulfide(MBTS)3.Summary of Test Method3.1 This test method allows for the determination of2-Mercaptobenzothiazole in cured rubber by high performanceliquid chromatography apparatus equipped with a diode-arraydetector(HPLC-DAD).The test is conducted after ultrasoundextraction of the test sample with a chloroform-methanolmixture and shaking extraction with a simulated acid sweatsolution.4.Significance and Use4.1 MBT is commonly used in rubber compounding as acuring accelerator for rubber and latex products.The determi-nation of MBT in cured rubber is important to assess the riskof a release of this hazardous substance when rubber is inprolonged contact with human skin or mucous membranes.4.2 Neo-formed MBT from MBTS might be created duringthe process of vulcanization when benzothiazolesulfenamidesare used in the compound as accelerators,and therefore,it ispart of the total MBT content in the cured rubber.4.3 The purity of MBT as raw material can be evaluated byfollowing Test Method D1991 based on a potentiometrictitration of MBT with sodium hydroxide.4.4 MBT is also a major impurity in MBTS.While MBTSis sparingly soluble in any organic solvent,MBT is verysoluble.The amount of MBT contained in MBTS as rawmaterial can be determined according to Test Method D5044.4.5 This test method may be used as a quality control tool aswell as for research and development work.5.Apparatus5.1 High performance liquid chromatography apparatusequipped with a diode-array detector(HPLC-DAD).5.2 Analytical Balance,accuracy 60.1 mg.5.3 Ultrasonic Extraction Apparatus,with a frequency of 406 5 kHz.5.4 Shaking Table,with water bath and variable frequency.5.5 pH Meter,(digital is recommended),having an accuracyof 6 0.05 pH.5.6 Volumetric Flask,100 cm3.5.7 Conical flask with stopper,250 cm3.5.8 Volumetric Flask,1 dm3.5.9 Filter Paper,quantitative.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand Rubber-like Materials and is the direct responsibility of Subcommittee D11.20on Compounding Materials and Procedures.Current edition approved Oct.1,2021.Published October 2021.DOI:10.1520/D8411-21.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.15.10 Filtration Membrane,organic type with a pore size of0.45 m.5.11 Flask with stopper,20 cm3.5.12 Pipette,10 cm3.6.Reagents and Materials6.1 Purity of ReagentsReagent grade or analytical gradechemicals shall be used in all tests.Unless otherwise indicated,it is intended that all reagents shall conform to the specifica-tions of the Committee onAnalytical Reagents of theAmericanChemical Society,where such specifications are available.3Other grades may be used,provided it is first ascertained thatthe reagent is of sufficiently high purity to perm