1、Designation: D 4275 09Standard Test Method forDetermination of Butylated Hydroxy Toluene (BHT) inPolymers of Ethylene and EthyleneVinyl Acetate (EVA)Copolymers By Gas Chromatography1This standard is issued under the fixed designation D 4275; the number immediately following the designation indicates
2、 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 test method describes a procedure for the
3、determi-nation of butylated hydroxy toluene (BHT) (2,6-di-t-butyl-4-methyl-hydroxybenzene) in polymers of ethylene andethylene-vinyl acetate (EVA) copolymers by solvent extractionfollowed by gas chromatographic analysis. Detection of thecompound is achieved by flame ionization, and quantitativeanaly
4、sis is obtained by use of internal or external standards, asdescribed in Practices E 260, E 355, and E 594.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety conce
5、rns, 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.NOTE 1There is no known
6、ISO equivalent for this test method.2. Referenced Documents2.1 ASTM Standards:2D 4968 Guide for Annual Review of Test Methods andSpecifications for PlasticsD 7210 Practice for Extraction of Additives in PolyolefinPlasticsE 260 Practice for Packed Column Gas ChromatographyE 355 Practice for Gas Chrom
7、atography Terms and Rela-tionshipsE 594 Practice for Testing Flame Ionization Detectors Usedin Gas or Supercritical Fluid ChromatographyE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI-10 Practice for Use of the InternationalSystem of Unit
8、s (SI) (the Modernized Metric System)3. Terminology3.1 DefinitionsUnits and symbols used in this test methodare those recommended in Practice IEEE/ASTM SI-10. Chro-matographic terms and relationships are as described in Prac-tice E 355.3.2 Abbreviations:Abbreviations:3.2.1 BHTButylated hydroxy tolue
9、ne (2,6-di-tert-butyl-4-methyl-hydroxybenzene).3.2.2 MMMethyl myristate.3.2.3 EVAEthylene-vinyl acetate copolymers.3.2.4 LDPELow-density polyethylene.3.2.5 HDPEHigh-density polyethylene.4. Summary of Test Method4.1 The BHT from a finely ground polymer sample isextracted by shaking or refluxing with
10、cyclohexane or isopro-panol. A known volume of this extract is injected into a gaschromatographic column packed with a liquid-coated solidsupport. Passing through this column in a stream of carrier gas,BHT is separated from the extraction solvent and othercomponents. Responses of BHT and any interna
11、l standard aremeasured by a flame ionization detector. This signal is re-corded to indicate the relative concentration and retention timeof BHT.5. Significance and Use5.1 Separation and identification of stabilizers used in themanufacture of polyethylene are necessary in order to correlateperformanc
12、e properties with polymer composition.1This 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 Aug. 1, 2009. Published August 2009. Originallyapproved in 1983. Last previous edi
13、tion approved in 2002 as D 4275 - 02.2For 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.1Copyright ASTM Internat
14、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 The BHT extraction procedure is made effective by theinsolubility of the polymer sample in solvents generally usedfor gas chromatographic analysis.6. Interferences6.1 Any material eluting at or near the BH
15、T or MMretention times will cause erroneous results. Prior to extraction,solvent blanks shall be analyzed to confirm the absence ofinterfering peaks.7. Apparatus7.1 Reflux Extraction, consisting of 250-mL round-bottomflask with condenser and heating mantle to fit.7.2 Wiley Mill, with 10 and 20-mesh
16、screens.7.3 Wrist-Action Shaker.7.4 Gas Chromatograph, equipped with a flame ionizationdetector.7.5 Chromatographic Column, 3.2-mm outside diametertimes 1.8 m packed with 20 % UCW-98 on 80/100 meshChromosorb P, a similar packed column, or an equivalentcapillary column, such as a HP-1 or DB-1.7.6 Int
17、egrator, capable of measuring the net peak area onthe back side of a solvent peak.7.7 Gas Chromatographic Syringe,10L.7.8 Analytical Balance, capable of weighing to 60.0001 g.7.9 Pressure Regulators, for all required gas cylinders.7.10 Filter-Dried Assemblies, for each required gas cylin-der.7.11 So
18、ap Film Flowmeter and Stopwatch, or other meansof measuring gas flow rates.8. Reagents and Materials8.1 Cyclohexane, reagent grade.8.2 Isopropyl Alcohol, reagent grade.8.3 Methyl Myristate,399+%, boiling point 323C (internalstandard).8.4 Butylated Hydroxy Toluene, food grade (2,6-di-tert-butyl-4-met
19、hyl-hydroxybenzene).8.5 Hydrogen Cylinder, prepurified.8.6 Nitrogen Cylinder, prepurified, oxygen-free for carriergas.NOTE 2Helium or hydrogen may also be used as the carrier gas.8.7 Air, breathing or water-pumped.9. Safety Precautions9.1 Cyclohexane and isopropyl alcohol are flammable. Thisextracti
20、on procedure should be carried out in a fume hood.10. Preparation of Gas Chromatograph10.1 Install the chromatographic column and conditionovernight at 200C with carrier gas flow rate of 35 mL/min. Donot connect the exit end of the column to the detector duringthis conditioning period. Turn off hydr
21、ogen and air flows to thedetector while the column is disconnected.10.2 Connect the exit end of the column to the detector. Setoptimum hydrogen and air flow rates for the detector asspecified for the chromatograph model in use, or as determinedexperimentally.10.3 Set chromatograph temperatures as fo
22、llows:10.3.1 Oven (chromatographic column), 160C.10.3.2 Injection block, 220C.10.3.3 Detector block, 240C.11. Calibration by Internal Standard11.1 Weigh a syringe containing approximately 80 mg ofmethyl myristate.11.2 Transfer syringe contents to a 2-L volumetric flask andimmediately reweigh the syr
23、inge (60.1 mg).11.3 Dilute to volume with extraction solvent (cyclohexaneor isopropyl alcohol) and store in a tightly stoppered flask.11.4 Weigh and transfer 20 6 0.1 mg of BHT into a 500-mLvolumetric flask.11.5 Dissolve BHT in the internal standard solution inaccordance with 11.3 and dilute to volu
24、me using this samesolution.11.6 Inject 2 L of this calibration mixture into the gaschromatograph equilibrated to the conditions of 10.3.11.7 Chromatograph BHT and MM and record their respec-tive peak areas using an integrator.NOTE 3The BHT and methyl myristate peak elute at approximately3.5 and 8 mi
25、n, respectively.11.8 Using BHT and MM areas from 11.7, determine therelative response factor (Rf) as follows:Rf5concentration mg/L! BHT 3 area MMconcentration mg/L! MM 3 area BHT(1)11.9 Average response factors for five replicate injections ofthe calibration mixture.12. Calibration by External Stand
26、ard12.1 Weigh 100 6 1 mg of BHT into a 200-mL volumetricflask.12.2 Dissolve in the selected extraction solvent (cyclohex-ane or isopropyl alcohol) and dilute to volume.12.3 Pipet 2.0, 4.0, 6.0, and 8.0 mL of the above stocksolution into a series of 100-mL volumetric flasks and dilute tovolume with t
27、he appropriate solvent.12.4 Inject 2 L of each dilute standard into the gaschromatograph equilibrated to the conditions of 10.3.12.5 Measure the BHT peak height (mm) and multiply bythe attenuation and range to obtain the total peak height foreach standard. Integrated peak areas can also be used.12.6
28、 Repeat injection of each standard and average the totalpeak height (or area) results for duplicate injections.12.7 Plot the total peak height (or area) on the y-axis versusconcentration (g/mL) for each standard on the x-axis. Theslope of this curve is proportional to the flame response forBHT.NOTE
29、4Chromatographic response for BHT should be determined byeach analyst every day. Observe that the curve intercept should be zero.3The sole source of supply of the methyl myristate known to the committee atthis time is Aldrich Chemical Co., P.O. Box 355, Milwaukee, WI 53201. If you areaware of altern
30、ative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee,1which you may attend.D427509213. Sample Preparation13.1 Grind HDPE, LDPE, and EVA samples containing lessthan 10
31、% vinyl acetate to 20-mesh size.13.2 Grind samples containing greater than 20 % vinylacetate to 10-mesh size.14. Procedure14.1 Isopropyl Alcohol Extraction:14.1.1 For analysis of LDPE or EVA, weigh 3 6 0.001 g ofground sample into a 250-mL round-bottom flask.14.1.2 Pipet 25.0 mL of isopropyl alcohol
32、 internal standardsolution prepared in 11.3 into the flask and connect it to thecondenser.NOTE 5With external standard calibration, substitute the appropriatesolvent for internal standard solution in 11.3 in the above procedure.14.1.3 Reflux 2 h and cool to room temperature beforeremoving the flask
33、from the condenser.14.2 Cyclohexane Extraction:14.2.1 For HDPE, repeat 14.1.1-14.1.3 , substituting cyclo-hexane for isopropyl alcohol.NOTE 6IPA can be used for HDPE extractions, but the recovery wasfound to be 10 % lower than with cyclohexane.14.2.2 For LDPE or EVA, weigh 3 6 0.001 g of groundsampl
34、e into a 250-mL round-bottom flask. Pipet 25.0 mL ofcyclohexane internal standard solution prepared in 11.3 into theflask and insert the stopper. Shake at room temperature for 2 hon a wrist-action shaker.14.3 Extract AnalysisInject 2 L of sample extract intothe gas chromatograph equilibrated to cond
35、itions of 10.3.Measure areas of BHT and methyl myristate peaks (if usinginternal standard calibration) and record as ABHT and AMM,respectively.NOTE 7Alternative extraction methods may be used in accordancewith Practice D 7210.15. Calculation15.1 Internal StandardUsing the response factor (Rf)determi
36、ned in 11.8 and area responses from chromatography ofsample extracts, calculate the BHT content of each samplefrom the following equation:ppm BHT 5ABHT!Rf!C!V!AMM! W!(2)where:ABHT= area of BHT peak in sample chromatogram,AMM= area of methyl myristate peak in sample chro-matogram,Rf= response factor
37、from 11.8,C = concentration of MM in the internal solution,mg/L,V = volume of internal standard solution used forextraction, mL, andW = weight of sample extracted, g.15.2 External StandardUsing the calibration slope from12.7, calculate the BHT content of each sample from thefollowing equation:BHT in
38、 ppm by weight! 5BVSW(3)where:B = BHT area or peak height from sample chromatogram,V = volume of extraction solution, mL,W = weight of sample extracted, g, andS = slope of calibration curve (from 12.7).16. Report16.1 Report the following information:16.1.1 Sample identification,16.1.2 Sample prepara
39、tion method used,16.1.3 Gas chromatography analysis method used, includ-ing type of calibration, and16.1.4 Concentration of BHT in the polymer, ppm.17. Precision and Bias17.1 PrecisionTable 1 is based on a round robin con-ducted in accordance with Practice E 691 involving twomaterials tested by five
40、 laboratories. For each material, allsamples were prepared at one source, but specimens wereprepared at the laboratories that tested them. Each test resultwas an average of two individual determinations. Each labo-ratory obtained two test results for each sample.17.2 Samples included HDPE and EVA(0
41、to 19 % VA) withBHT levels of 70 to 930 g/g.17.3 For HDPE containing 150 to 350-g/g ppm BHT,values determined using cyclohexane extraction averaged10 % higher than those derived from isopropanol extraction.17.4 BiasThere are no recognized standards by which toestimate the bias of this test method.NO
42、TE 8Caution should be exercised with the between-laboratoryresults since fewer than six laboratories participated in the round-robinstudy.18. Keywords18.1 butylated hydroxy toluene; BHT; ethylene-vinyl ac-etate; gas chromatography; polyethyleneTABLE 1 Summary of Method PrecisionExtraction SolventExp
43、ressed as Percent of the AverageCV %rACV %rBCV %RCIsopropanolCyclohexane2.72.95.04.97.47.4ACV %r= within laboratory coefficient of variation between a pair of replicates(expressed in percent).BCV %r= within laboratory coefficient of variation of the average of twoanalyses on different days (expresse
44、d in percent).CCV %R= between laboratory coefficient of variation of the average (ex-pressed in percent).D4275093ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advi
45、sed 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 years andif not revised, either
46、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 committee, which you may attend. If
47、 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 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).D4275094
