ASTM_D_6953_-_11.pdf

Designation:D695311Standard Test Method forDetermination of Antioxidants and Erucamide Slip Additivesin Polyethylene Using Liquid Chromatography(LC)1This standard is issued under the fixed designation D6953;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 covers a liquid-chromatographic pro-cedure for the separation of primary and secondary antioxidantand slip additives currently used in polyethylene plastics.These additives are extracted with either isopropanol(resindensities 0.94g/cm3)prior to liquid-chromatographic separation.The ultra-violet absorbance of the eluting compound(s)is measured andquantitation is performed using external calibration.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 and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 9.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD4697 Guide for Maintaining Test Methods in the UsersLaboratory(Withdrawn 2009)3E131 Terminology Relating to Molecular SpectroscopyE169 Practices for General Techniques of Ultraviolet-VisibleQuantitative AnalysisE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible SpectrophotometersE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1657 Practice for Testing Variable-Wavelength Photomet-ric Detectors Used in Liquid ChromatographyIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units(SI):The Modern Metric System3.Terminology3.1 Definitions:3.1.1 For definitions of plastic terms and detector terminol-ogy used in this test method,see Terminologies D883,D1600,and E1657.3.1.2 For units and symbols used in this test method,refer toTerminology E131 or IEEE/ASTM SI 10.4.Summary of Test Method4.1 The polyethylene sample is ground to a 1-mm(20mesh)or 0.5-mm(40 mesh)particle size and extracted byrefluxing with either isopropanol or cyclohexane.4.2 The solvent extract is analyzed by liquid chromatogra-phy.4.3 Additive concentrations are determined from externalcalibration curves using reverse phase chromatography(C-8 orC-18 column)with ultraviolet(UV)detection at wavelengthscorresponding to the wavelengths of an absorption apex ofeach additive(except erucamide which does not have anabsorption maximum in the accessible UV region).5.Significance and Use5.1 Separation and identification of stabilizers used in themanufacture of polyethylene resins are necessary in order tocorrelate performance properties with polymer composition.This test method provides a means to determine the polymeradditives listed in Table 1 in polyethylene samples.This testmethod is capable of the determination of other antioxidants,but the stability of these during extraction has not beeninvestigated.5.2 The additive extraction procedure is made effective bythe relatively low solubility of the polymer sample in solventsgenerally used for liquid chromatographic analysis.In this1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Sept.1,2011.Published September 2011.Originallyapproved in 2003.Last previous edition approved in 2003 as D6953-03.DOI:10.1520/D6953-11.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.*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 method,isopropanol and cyclohexane were chosen because oftheir excellent extraction efficiencies as well as for safetyreasons.Other solvents including ethylacetate,isobutanol,chloroform and methylene chloride can also be used.5.3 Methods other than refluxing that have been used toremove additives from the polymer matrix including pressur-ized liquid,microwave,ultrasonic,and supercritical fluidextractions.For the separation of the extracted additives,SFCand GC have been used successfully for several of theadditives.5.4 Under optimum conditions,