1、Designation: D 4275 02Standard 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 (e) 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 quantitativeanal
4、ysis 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 conc
5、erns, 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 simil
6、ar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:D 4968 Guide for Annual Review of Test Methods andSpecifications for Plastics2E 260 Practice for Packed Column Gas Chromatography2E 355 Practice for Gas Chromatography Terms and Rela-tionships3E 380 Practice for Use of the Inter
7、national System of Units(SI) (the Modernized Metric System)4E 594 Practice for Testing Flame Ionization Detectors Usedin Gas Chromatography3E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method33. Terminology3.1 DefinitionsUnits and symbols used in this te
8、st methodare those recommended in Practice E 380. Chromatographicterms and relationships are as described in Practice E 355.3.2 Abbreviations:Abbreviations:3.2.1 BHTButylated hydroxy toluene (2,6-di-tert-butyl-4-methyl-hydroxybenzene).3.2.2 MMMethyl myristate.3.2.3 EVAEthylene-vinyl acetate copolyme
9、rs.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 cyclohexane or isopro-panol that may contain an internal standard. A known volumeof this extract is injected int
10、o a gas chromatographic columnpacked with a liquid-coated solid support. Passing through thiscolumn in a stream of carrier gas, BHT is separated from theextraction solvent and other components. Responses of BHTand any internal standard are measured by a flame ionizationdetector. This signal is recor
11、ded to indicate the relativeconcentration and retention time of BHT.5. Significance and Use5.1 Separation and identification of stabilizers used in themanufacture of polyethylene are necessary in order to correlateperformance properties with polymer composition.5.2 The BHT extraction procedure is ma
12、de effective by theinsolubility of the polymer sample in solvents generally usedfor gas chromatographic analysis.6. Interferences6.1 Any material eluting at or near the BHT or MMretention times will cause erroneous results. Prior to extraction,solvent blanks should be analyzed to confirm the absence
13、 ofinterfering peaks.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. 10, 2002. Published October 2002. Originallypublished as D 4275 83. Last previous edition D 42
14、75 96.2Annual Book of ASTM Standards, Vol 08.03.3Annual Book of ASTM Standards, Vol 14.02.4Discontinued; see 1997 Annual Book of ASTM Standards , Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Apparatus7.1 Reflux Extrac
15、tion, consisting of 250-mL round-bottomflask with condenser and heating mantle to fit.7.2 Wiley Mill, with 10 and 20-mesh 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 % UC
16、W-98 on 80/100 meshChromosorb P, a similar packed column, or an equivalentcapillary column, such as a HP-1 or DB-1.7.6 Integrator, 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
17、 Pressure Regulators, for all required gas cylinders.7.10 Filter-Dried Assemblies, for each required gas cylin-der.7.11 Soap 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
18、 Myristate,599+%, boiling point 323C (internalstandard).8.4 Butylated Hydroxy Toluene, food grade (2,6-di-tert-butyl-4-methyl-hydroxybenzene).8.5 Hydrogen Cylinder, prepurified.8.6 Nitrogen Cylinder, prepurified, oxygen-free for carriergas.NOTE 2Helium may also be used as the carrier gas.8.7 Air, br
19、eathing or water-pumped.9. Safety Precautions9.1 Cyclohexane and isopropyl alcohol are flammable. Thisextraction 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
20、mL/min. Donot connect the exit end of the column to the detector duringthis conditioning period. Turn off hydrogen 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 asspecifie
21、d for the chromatograph model in use, or as determinedexperimentally.10.3 Set chromatograph temperatures as follows: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
22、 mg ofmethyl myristate.11.2 Transfer syringe contents to a 2-L volumetric flask andimmediately reweigh the syringe (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-mL
23、volumetric flask.11.5 Dissolve BHT in the internal standard solution inaccordance with 11.3 and dilute to volume 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-
24、tive peak areas using an integrator.NOTE 3The BHT and methyl myristate peak elute at approximately3.5 and 8 min, 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 Aver
25、age response factors for five replicate injections ofthe calibration mixture.12. Calibration by External Standard12.1 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
26、.0, and 8.0 mL of the above stocksolution into a series of 100-mL volumetric flasks and dilute tovolume with the 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 atten
27、uation and range to obtain the total peak height foreach standard. Integrated peak areas can also be used.12.6 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/
28、mL) for each standard on the x-axis. Theslope of this curve is proportional to the flame response forBHT.NOTE 4Chromatographic response for BHT should be determined byeach analyst every day. Observe that the curve intercept should be zero.13. Sample Preparation13.1 Grind HDPE, LDPE, and EVA samples
29、containing lessthan 10 % 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
30、mL of isopropyl alcohol internal standardsolution prepared in 11.3 into the flask and connect it to thecondenser.5Available from Aldrich Chemical Co., P.O. Box 355, Milwaukee, WI 53201.D4275022NOTE 5With external standard calibration, substitute the appropriatesolvent for internal standard solution
31、in 11.3 in the above procedure.14.1.3 Reflux 2 h and cool to room temperature beforeremoving the flask 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 w
32、asfound to be 10 % lower than with cyclohexane.14.2.2 For LDPE or EVA, weigh 3 6 0.001 g of groundsample 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
33、shaker.14.3 Extract AnalysisInject 2 L of sample extract intothe gas chromatograph equilibrated to conditions of 10.3.Measure areas of BHT and methyl myristate peaks (if usinginternal standard calibration) and record as ABHT and AMM,respectively.15. Calculation15.1 Internal StandardUsing the respons
34、e factor (Rf)determined 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,
35、Rf= response factor 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 thefollo
36、wing equation:BHT in 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,1
37、6.1.2 Sample preparation 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 twomate
38、rials tested by five 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 incl
39、uded HDPE and EVA(0 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
40、 this test method.NOTE 7Caution 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 PrecisionE
41、xtraction SolventExpressed 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 diff
42、erent days (expressed in percent).CCV %R= between laboratory coefficient of variation of the average (ex-pressed in percent).D4275023ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standar
43、d are expressly advised 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
44、not revised, either 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, whic
45、h you may attend. If 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).D4275024
