1、Designation: D 6042 09Standard Test Method forDetermination of Phenolic Antioxidants and Erucamide SlipAdditives in Polypropylene Homopolymer FormulationsUsing Liquid Chromatography (LC)1This standard is issued under the fixed designation D 6042; the number immediately following the designation indi
2、cates 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-chromato
3、graphic pro-cedure for the separation of some additives currently used inpolypropylene. These additives are extracted with a cyclohex-ane:methylene chloride mixture using either reflux or ultra-sonic bath prior to liquid-chromatographic separation. Theultraviolet absorbance (200 nm) of the compound(
4、s) is mea-sured, and 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 de
5、termine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 9.NOTE 1There is no known ISO equivalent to this test method.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsD 1600 Terminology for Abbreviated
6、Terms Relating toPlasticsE 131 Terminology Relating to Molecular SpectroscopyE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodIEEE/ASTM SI-10 Practice for Use of the InternationalSystem of Units (SI) (the Modernized Metric System)3. Terminology3.1 For
7、definitions of plastic terms used in this test method,see Terminologies D 883 and D 1600.3.2 For the units, symbols, and abbreviations used in thistest method, refer to Terminology E 131 or Practice IEEE/ASTM SI-10.3.3 Abbreviations:Abbreviations:3.3.1 LCliquid chromatography.3.3.2 PPpolypropylene.3
8、.4 Trade Names:3.5 Vitamin Ea-Tocopherol, or 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-ol.3.6 Irgafos 168Tris(2,4 di-tert-butylphenyl) phosphite.3.7 Irganox 3114Tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate.3.8 Kemamide-Ecis-13-docosenamide or erucamide.3.9 Ir
9、ganox 1010tetrakismethylene(3,5-di-t-butyl-4-hydroxy hydrocinnamate)methane.3.10 Irganox 1076octadecyl-3,5-di-t-butyl-4-hydroxy hy-drocinnamate.3.11 Tinuvin P2(28-hydroxy-58-methyl phenyl)benzotria-zole.4. Summary of Test Method4.1 The PP sample is ground to a 20-mesh particle size (850microns) and
10、extracted by refluxing with a mixture of 75:25methylene chloride:cyclohexane or placing in an ultrasonicbath with the same mixture.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
11、 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 polypropylene is necessary in order to correlateperformance properties with polymer composition. This testmethod provi
12、des a means to determine erucamide slip, VitaminE, Irgafos 168, Irganox 3114, Irganox 1010, and Irganox 1076levels in polypropylene samples. This test method is also1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on
13、 Analytical Methods(D20.70.02).Current edition approved Sept. 1, 2009. Published September 2009. Originallyapproved in 1996. Last previous edition approved in 2004 as D 6042 - 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
14、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.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.a
15、pplicable for the determination of other antioxidants, such asUltranox 626, Ethanox 330, Santanox R, and BHT, but theapplicability of this test method has not been investigated forthese antioxidants.5.2 The additive-extraction procedure is made effective bythe insolubility of the polymer sample in s
16、olvents generallyused for liquid chromatographic analysis.5.3 Under optimum conditions, the lowest level of detectionfor a phenolic antioxidant is approximately 2 ppm.NOTE 2Other methods that have been used successfully to removeadditives from the plastics matrix include thin film, microwave, ultras
17、onic,and supercritical fluid extractions. Other methods have been used success-fully to separate additives including SFC and capillary GC.5.4 Irgafos 168 is a phosphite antioxidant. Phosphites areknown to undergo both oxidation and hydrolysis reactions.Less Irgafos 168 will be determined in the poly
18、mer whenoxidation occurs during processing. The HPLC separation iscapable of separating the phosphite, phosphate (oxidationproduct), and hydrolysis product and quantify them if stan-dards are obtained. No significant breakdown of the phosphiteantioxidant has been seen due to either extraction techni
19、que orthe separation presented in this standard.6. Interferences6.1 Any material eluting at or near the same retention timeas the additive has been known to cause erroneous results.Examining a polymer-solvent-extract solution containing nointernal standard is recommended to minimize the possibilityo
20、f interferences.6.2 Solvent impurity is a major source of interference. It isa good practice to examine the solvents prior to use byinjecting a sample of solvent on the HPLC system andanalyzing as in Section 10.6.3 The oxidation product of Irgafos 168 sometimes over-laps with other additives with re
21、tention times of componentsthat elute between Irganox 1010 and Irgafos 168. In thesecases, run known standards to ensure that components ofinterest do not coelute with the oxidation product of Irgafos168.7. Apparatus7.1 Liquid Chromatograph, equipped with a sample injec-tor, variable-wavelength ultr
22、aviolet detector, heated column,and gradient-elution capabilities.7.2 Chromatographic Column, RP-18, 5-m particle size,15 cm by 4.6 mm.NOTE 3A Zorbax RX C-18 Column by Agilent was used for this testmethod. The gradient described in 10.1 provides complete separation ofantioxidants using this C-18 col
23、umn.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 water-cooled jacket to prevent thermodegradation of antioxidants.7.5 Recorder, mV scale dependent upon the output of thedetector.7.6 Reflux Ex
24、traction Apparatus, consisting of a condenser(24/40 ground-glass joint), a flat bottom 125 mL flask havinga 24/40 ground-glass joint, and a hot plate with magnetic stirrer(see Fig. 1).7.7 Ultrasonic Bath Apparatus, consisting of the ultrasonicbath, a flat bottom 125-mL flask having a 24/40 ground-gl
25、assjoint, and a 24/40 ground-glass stopper.7.8 Filter System (Teflon)3for nonaqueous solutions (poresize of 0.45 m or less) equipped with a glass 5-cm3syringe.NOTE 4The filter shall give no ghost peak with blank solvent.7.9 Analytical Balance, capable of weighing to 60.0001 g.8. Reagents and Materia
26、ls8.1 Tinuvin-P, 2(28 hydroxy-58-methyl phenyl) benzotriaz-ole.8.2 Methylene Chloride, HPLC grade, spectral quality orchromatography quality reagent.8.3 Cyclohexane, HPLC grade, spectral quality or chroma-tography quality reagent.8.4 75:25 Methylene Chloride:Cyclohexane T-P, mixturewith 51.8 mg/L Ti
27、nuvin-P added as an internal standard.3Registered trademark of DuPont.FIG. 1 Sample ExtractionD60420928.5 Water, HPLC or UV quality reagent, degassed bysparging with high purity helium or by filtration under vacuum.8.6 Acetonitrile, HPLC, spectral quality or chromatographyquality reagent (a reagent
28、whose UV cut-off is about 190 nm).8.7 Isopropanol, HPLC, spectral quality or chromatographyquality reagent.9. Safety and Precautions9.1 Methylene chloride and cyclohexane are flammable andtoxic. Perform this extraction procedure in a fume hood.10. Preparation of Liquid Chromatograph10.1 Set the chro
29、matograph to operate at the followingconditions (see Fig. 2 for an example chromatogram):10.1.1 Initial Mobile Phase Condition75 % acetonitrile:25 % water or whatever is appropriate for column used in orderto retain Tinuvin P longer than solvent breakthrough.10.1.2 Final Mobile Phase Condition100 %
30、acetonitrile:0 % water.10.1.3 Gradient Length5 min or whatever is appropriateto cause a complete separation of additives and have a totalchromatogram analysis time of 20 min or less.10.1.4 Gradient CurveLinear.10.1.5 Flow Rate1.5 mL/min.10.1.6 Hold at 100 % acetonitrile: 0 % water for 10 min orwhate
31、ver is required to allow all additives to elute.10.1.7 At 15.1 min return to 75 % acetonitrile: 25 % waterat a flow of 1.5 mL/min for 5 min.10.1.8 DetectorUltraviolet detector set at 200 nm, rangeset at about 0.1 Aufs.10.1.9 ColumnReverse-phase C-18, 5 m, 15 cm by 4.6mm.10.1.10 TemperatureColumn set
32、 at 50C.10.1.11 Sample Size10 L or less, depends on sampleconcentration and instrument.11. Sample Preparation11.1 Grind the sample to a particle size of 20-mesh using awater-cooled Wiley mill.NOTE 5Grind 7 to8gofthesample to run the analysis. It is importantto minimize the time of grinding to preven
33、t any thermodegradation of theadditives in the polymer.11.2 For reflux extraction, weigh 5 6 0.01 g of the sampleinto a 125 mL flat bottom flask, add a stirring bar, add by pipet50.0 mL of methylene chloride:cyclohexane T-P solvent con-taining the internal standard, and boil for 90 min (with stirrin
34、g)using the reflux apparatus.NOTE 6The internal standard is present in the extraction solvent (51.8g/mL).11.3 For ultrasonic bath extraction, weigh 5 6 0.01 g of thesample into a 125-mL flat bottom flask, add by pipet 50.0 mLof methylene chloride:cyclohexane T-P solvent containing theinternal standa
35、rd, stopper flask, and place in an ultrasonic bath.Turn on the ultrasonic bath and extract for 1 h.11.4 Cool the solution to room temperature by raising theflask off the hot plate while still attached to the condenser.11.5 Attach a filter disc assembly to a 5-L Luer-Lok tiphypodermic syringe (see Fi
36、g. 3).11.6 Decant or pipet 4 mL of the solvent extract into theabove syringe.11.7 Insert the plunger and carefully apply pressure to forcethe solvent extract through the filter into a sample vial.12. Calibration by Internal Standard12.1 Weigh accurately into a 125-mL flat bottom flask 50 61 mg of th
37、e desired additive. Weigh 51.8 mg of Tinuvin-P intothe flask. Dissolve the components in 510 mL of warmisopropanol. Transfer the solution mixture to a 1000 mLvolumetric flask and dilute to volume with isopropanol. Capflask and mix thoroughly.FIG. 2 HPLC Separation of Six AdditivesD6042093NOTE 7Vitam
38、in E must be prepared and used in the same day orstored in an amber bottle due to photodecomposition.12.2 Standardize the liquid chromatograph detector re-sponse by injection of 10 L of the solution at the conditionslisted in 10.1.12.3 Measure the peak areas using a computer or anintegrator and calc
39、ulate the relative response factor (R).R 5Concentration mg/L! Additive 3 Area Tinuvin2PConcentration mg/L! Tinuvin2P 3 Area Additive(1)12.4 Average the response factors for three replicate injec-tions of the calibration mixture.NOTE 8Tinuvin-P shall not be used as internal standard when thiscompound
40、 is expected to be found as an additive in samples beinganalyzed.13. Procedure13.1 Ensure that the liquid chromatograph is set at theconditions prescribed in Section 10.13.2 Inject 10 L of the sample solution into the liquidchromatograph system.14. Calculation14.1 Internal StandardUsing the response
41、 factor deter-mined in 12.3 and area responses from chromatography ofsample extracts, calculate the additive content of each samplefrom the following equation:Additive ppm!5A 3 R 3 Cis 3 VW 3 Ais(2)where:A = area of additive,R = response factor,Cis = concentration of internal standard,V = volume of
42、extraction solvent (Tinuvin-P added), mL,W = weight of sample extracted, g, andAis = area in internal standard.15. Report15.1 Report the additive (ppm) calculated in 14.1.16. Precision and Bias16.1 Table 1 is based on an interlaboratory study4conductedin 1995 in accordance with Practice E 691 involv
43、ing twomaterials tested using two different techniques at elevendifferent laboratories. The additives in these materials wereprepared at two different companies. The materials were sentout to participants for grinding, solvent extraction, and furtheranalysis. Each test result is an individual determ
44、ination. Eachlaboratory obtained three test results for each material usingeither the ultrasonic or reflux extraction method (or both). Eachtest was performed on a different day. WarningThe follow-ing explanations of r and R (16.1 through 16.1.3) only areintended to present a meaningful way of consi
45、dering theapproximate precision of this test method. Do not apply thedata in Table 1 to the acceptance or rejection of material, asthose data are specific to the round robin and are unlikely to berepresentative of other lots, conditions, materials, or laborato-ries. Use the principles outlined in Pr
46、actice E 691 to generatedata specific to their laboratory and materials or betweenspecific laboratories. The principles of 16.1 through 16.1.3 thenwould be valid for such data.16.1.1 Repeatability Limit, r (comparing two test results forthe same material, obtained by the same operator using thesame
47、equipment on the same day)The two test results shallbe judged not equivalent if they differ by more than the r valuefor that material.16.1.2 Reproducibility Limit, R (comparing two test resultsfor the same material, obtained by different operators usingdifferent equipment in different laboratories)T
48、he two testresults shall be judged not equivalent if they differ by morethan the R value for that material.16.1.3 Any judgment in accordance with 16.1.2 or 16.1.3would have an approximate 95 % (0.95) probability of beingcorrect.16.2 There are no recognized standards by which to esti-mate bias of thi
49、s test method. Targeted additive levels are givenin Table 1 to be used as an estimate for recovery.17. Keywords17.1 additive; antioxidants; erucamide slip; extraction; Ir-gafos 168; Irganox 1010; Irganox 1076; Irganox 3114; liquidchromatography (LC); polypropylene (PP); vitamin E4Supporting data are available from ASTM Headquarters. Request RR:D 20-1193.FIG. 3 Final Preparation of Sample ExtractD6042094SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue(D 6042 - 04) that may
