ASTM_D_1996_-_97_2003.pdf

Designation:D 1996 97(Reapproved 2003)Standard Test Method forDetermination of Phenolic Antioxidants and Erucamide SlipAdditives in Low Density Polyethylene Using LiquidChromatography(LC)1This standard is issued under the fixed designation D 1996;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(e)indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method describes a liquid chromatographprocedure for the separation of some additives currently usedin low density polyethylene.These additives are extracted with2-propanol prior to liquid chromatographic separation.Theultraviolet absorbance(200 nm)of the compound(s)is mea-sured;quantitation is performed using the internal standardmethod.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 determine the applica-bility of regulatory limitations prior to use.For a specifichazards statement,see Section 9.NOTE1There is no similar or equivalent ISO standard.2.Referenced Documents2.1 ASTM Standards:E 131 Terminology Relating to Molecular Spectroscopy2E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3E 682 Practice for Liquid Chromatography Terms and Re-lationships2E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3IEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units(SI)33.Terminology3.1 Abbreviations:3.1.1 BHEB2,6-di-t-butyl-4-ethyl-hydroxybenzene or bu-tylated hydroxyethylbenzene.3.1.2 BHT2,6-di-t-butyl-4-methyl hydroxybenzene or bu-tylated hydroxytoluene.3.1.3 Irganox 1010tetrakismethylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate).3.1.4 Irganox1076octadecyl3-(38,58-t-butyl-4-hydroxyphenyl)propionate.3.1.5 Isonox 1292,28-ethylidene bis(4,6-di-t-butyl hy-droxybenzene).3.1.6 Kemamide-Ecis-13-docosenamide,erucamide.3.1.7 LCliquid chromatography.3.1.8 LDPElow density polyethylene.3.1.9 Tinuvin P2(28-hydroxy-58-methyl phenyl)benzot-riazole,Ciba-Geigy Industrial Chemicals.4.Summary of Test Method4.1 The LDPE sample is ground to a 20-mesh particle sizeand extracted by refluxing with 2-propanol.4.2 The solvent extract is examined by liquid chromatogra-phy.4.3 Additive concentrations are determined relative to aninternal standard(contained in the solvent)using reverse phasechromatography(C-18 column)with ultraviolet(UV)detectionat 200 nm.5.Significance and Use5.1 Separation and identification of stabilizers used in themanufacture of low density polyethylene are necessary in orderto correlate performance properties with polymer composition.This test method provides a means to determine the BHT,BHEB,Isonox-129,erucamide slip,Irganox-1010 and Irganox-1076 levels in low density polyethylene samples.5.2 The additive extraction procedure is made effective bythe insolubility of the polymer sample in solvents generallyused for liquid chromatographic analysis.5.3 Under optimum conditions,the lowest level of detectionfor a phenolic antioxidant is approximately 2 ppm.6.Interferences6.1 Any material eluting at or near the same retention timesas the additive or as the internal standard can cause erroneousresults.A polymer solvent extract solution containing no1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.15 on Thermoplastic Materi-als.Current edition approved March 10,2003.Published April 2003.Originallyapproved in 1992.Last previous edition approved in 1997 as D 1996 97.2Annual Book of ASTM Standards,Vol 03.06.3Annual Book of ASTM Standards,Vol 14.02.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.internal standard should be examined to minimize the possi-bility of interferences.6.2 A major source of interferences can be from solventimpurities;therefore,the solvents should be examined prior touse.7.Apparatus7.1 Liquid Chromatograph,equipped with a variable wave-length ultraviolet detector,heated column,and gradient elutioncapabilities.The liquid chromatograph should be equippedwith a means for a 10-microliter sample solution injection suchas a sample loop.7.2 Chromatographic Column,RP-18,5 micron sphericalparticle,15 by 4.6 mm;Vydac 201TP5415,Separations Groupor equivalent.7.3 Computer System or Integrator coupled with the chro-matograph is recommended to measure peak area.7.4 Wiley Mill,equipped with a 20-mesh screen and watercooled jacket to prevent thermodegradation of antioxidantssuch as BHT and BHEB.7.5 Recorder,mv scale dependent upon the output of thedetector.7.6 Reflux Extraction Apparatus,consisting of a condenser(24/40 gr