1、Designation: D2426 93 (Reapproved 2009)Standard Test Method forButadiene Dimer and Styrene in Butadiene Concentrates byGas Chromatography1This standard is issued under the fixed designation D2426; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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 covers the determination of butadienedimer (4-vinylcyclohexene-1) and styre
3、ne in butadiene concen-trates, both recycle and specification grade.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
4、 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 specificprecautionary statements see Sections 6 and 8.2. Referenced Documents2.1 ASTM Standards:2D1657 Test Method for
5、 Density or Relative Density ofLight Hydrocarbons by Pressure HydrometerD1945 Test Method for Analysis of Natural Gas by GasChromatographyD2593 Test Method for Butadiene Purity and HydrocarbonImpurities by Gas Chromatography2.2 Other Documents:2STP 109A Physical Constants of Hydrocarbons C1to C103.
6、Summary of Test Method3.1 The sample is introduced into a gas-liquid partitioncolumn. The components of interest are separated as they aretransported through the column by a carrier gas, and theirpresence in the effluent is detected and recorded as a chromato-gram. Packed columns are used, and eithe
7、r thermal conductiv-ity or ionization detectors are permissible. The quantity of thecomponents of interest present in the sample is determinedfrom the chromatogram by comparing their peak areas orheights with those obtained from a synthetic sample.4. Significance and Use4.1 Butadiene dimer and styre
8、ne may be present as impuri-ties in commercial butadiene. This test method is suitable foruse in internal quality control and in establishing productspecifications.5. Apparatus5.1 ChromatographAny chromatograph having either athermal conductivity or flame ionization detector may be used.The detector
9、 system shall have sufficient sensitivity to obtain adeflection of at least 2 mm at a signal-to-noise ratio of at least5:1 for 0.01 weight % of butadiene dimer and styrene under theoperating conditions prescribed in this test method.5.2 RecorderA0 to 1-mV, 0 to 5-mV, or 0 to 10-mVrecorder with a ful
10、l-scale response time of2sorless, and withsufficient sensitivity to meet the requirements of 5.1.5.3 ColumnAny column may be used that is capable ofresolving the butadiene dimer and styrene as discrete peaks,quantitatively proportional to concentration and within anelapsed time sufficiently short to
11、 be practical.5.4 Liquid Sampling ValveAny liquid sampling valve maybe used that will permit the reproducible introduction of thebutadiene concentrate as a liquid under its vapor pressure orhigher and in a quantity sufficient to meet the sensitivity andresolution requirements in 5.1 and 5.3, respect
12、ively.36. Reagents and Materials6.1 4-vinylcyclohexene-1 and Styrene, for calibration, purityof not less than 99 %.6.2 Carrier GasHelium or hydrogen for use on thermalconductivity detector units; or nitrogen, helium, or argon foruse on ionization detector units. (WarningCompressed gas.Hazardous pres
13、sure.) (WarningHydrogen gas is flammable.Hazardous pressure.)6.3 Liquid Phase, for column.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.D0.04 on C4 Hydrocarbons.Current edition approved July 1
14、, 2009. Published November 2009. Originallyapproved in 1965. Last previous edition approved in 2004 as D242693(2004)1.DOI: 10.1520/D2426-93R09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vo
15、lume information, refer to the standards Document Summary page onthe ASTM website.3Suitable valves are commercially available.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 1The following materials have been used successfully a
16、s liquidphases (see Table 1)4:Carbowax 400, 1500, 1540General Electric SE-30 silicone gum rubberPolyethylene glycol 6000Barecowax 1035Dow Corning silicone oilCarbowax 20M + Dow Corning Hi Vac.6.4 Solid Support, for use in packed column, usuallycrushed fire brick or diatomaceous earth. Sieve size wil
17、ldepend on the diameter of the column used and support loadingand should be such as to give optimum resolution and analysistime.7. Preparation of Apparatus7.1 Column PreparationAny satisfactory method, used inthe practice of the art, that will produce a column meeting therequirements of 5.3. SeeAppe
18、ndix X2, Sample Calculations, ofTest Method D1945, also see 6.1, Carrier Gas, of Test MethodD2593.7.2 ChromatographPut in service in accordance with themanufacturers instructions. The injector temperature shall beno greater than 5C above the column oven temperature. Thecolumn oven temperature shall
19、not exceed 185C. See Table 1for typical operating conditions.7.3 Synthetic BlendsPrepare a synthetic mixture from 99mol % minimum pure 4-vinylcyclohexene-1 and styrene in asuitable matrix in approximately the same concentration ex-pected in the sample. The matrix may be any one of the normalparaffin
20、 hydrocarbons from butane to heptane, inclusive. Inpreparing the blend, weigh each compound added with suffi-cient precision to result in a mixture accurate to 5 % relative or0.02 % absolute, whichever is greater. Transfer the blend to acontainer of the type to be used for the sample and pressurewit
21、h a suitable gas.8. Procedure8.1 Using the liquid sampling valve, inject into the columnthe desired volume of synthetic blend and record the peaks ata sensitivity setting that allows the maximum peak height.Pressure the sample cylinder with a suitable gas to a pressuresufficient to ensure no flashin
22、g in the line to the sampling valveor in the valve itself. Using the same sample size andinstrument conditions, inject the sample into the column andrecord the peaks. (See Table 1 for typical operating conditions.)(WarningButadiene gas is flammable under pressure.)9. Calculation9.1 Peak MeasurementM
23、easure the peak area or height ofeach component of interest in both the synthetic blend and thesample. Measurement may be accomplished by any methodthat meets the precision requirements of Section 10. Areamethods found to be acceptable include planimetering, inte-gration, and triangulation (multiply
24、ing the peak height by thewidth at the half-height). In peak area or height methods caremust be taken so that chromatograph operating parameterssuch as column temperature and carrier gas flow rate are keptat the same conditions on both the synthetic standard and thesample. Calculate the percentage b
25、y weight of each componentas follows:Concentration, weight % 5 As/Ao! 3 S 3 Go/Gs! (1)where:As= peak area or height of component in the sample,Ao= peak area or height of component in the syntheticblend,S = weight % of component in the synthetic blend,Gs= relative density 60/60 of the sample, andGo=
26、relative density 60/60 of the synthetic blend.NOTE 2The specific gravity of the sample may be determined inaccordance with Test Method D1657 and the specific gravity of thesynthetic may be assumed to be equal to the gravity of solvent used toprepare the blend. A list of such gravities is found in ST
27、P 109A.10. Precision and Bias10.1 The precision of this test method as determined bystatistical examination of interlaboratory results is as follows:10.1.1 RepeatabilityThe difference between successivetest results, obtained by the same operator with the sameapparatus under constant operating condit
28、ions on identical testmaterial would, in the long run, and in the normal and correctoperation of the test method, exceed the following values onlyin one case in twenty:Concentration RepeatabilityDimer, wt %Styrene, wt %0.151.490.0050.0444If you are aware of alternative suppliers, please provide this
29、 information toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.TABLE 1 Columns and Conditions Used SuccessfullyDow Silicone200Carbowax1500Carbowax1540Silicone SE-30Carbowax20M + DowCorning Hi
30、 VacPolyethyleneGlycol-6000Barecowax1035Column length, m 1.5 4.6 3.7 15.2 3.1 3.7 6.1Column diameter, mm 3.2 4.8 6.4 0.5 6.4 4.8 6.4Column temperature, C 85 110 100 75 100128 155 140Liquid phase, wt % 10 15 16 . 0.75 each 30 20Support material Chromosorb P TFE-fluorocarbon Chromosorb P (Coated) Sili
31、ca Chromosorb P Chromosorb PMesh 80100 4060 100120 . . 3050 6080Carrier flow, mL/min 19 60 60 15 30 171 60Detector HFIAT.C.BHFI HFI T.C. T.C. T.C.Sample size, L 0.77 20 0.07 1.54 1.03 8.69 3.0Peak measurement triangulation triangulation integrator triangulation triangulation peak height planimeterAH
32、FI = hydrogen flame ionization.BT.C. = thermal conductivity.D2426 93 (2009)210.1.2 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, and in the normal and correc
33、t operation of the testmethod, exceed the following values only in one case intwenty:Concentration ReproducibilityDimer, wt %Styrene, wt%0.151.490.0180.05110.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod for measuring dimer
34、and styrene, bias has not beendetermined.11. Keywords11.1 butadiene concentrate; butadiene dimer; gas chroma-tography; styreneASTM 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 e
35、xpressly 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 not rev
36、ised, 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, which you m
37、ay 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 St
38、ates. 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D2426 93 (2009)3
