1、Designation:D242693(Reapproved 2014)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 of r
2、evision,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 styrene in butadie
3、neconcentrates,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 is theresponsibilit
4、y 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 Density or Relative D
5、ensity of LightHydrocarbons 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.Summary of Test Method3
6、.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 either thermal conductiv-ity or
7、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 styrene may be present as impuri-t
8、ies 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 system shall have sufficient s
9、ensitivity 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 RecorderA 0 to 1-mV,0 to 5-mV,or 0 to 10-mVrecorder with a full-scale response time of 2 s or le
10、ss,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 be practical.5.4 Liquid Sampli
11、ng 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,respectively.NOTE1Suitable valves are c
12、ommercially available6.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.Hazardou
13、s pressure.)(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,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.D0.04 on C4 Hydrocarbons.Current editio
14、n approved May 1,2014.Published July 2014.Originally approvedin 1965.Last previous edition approved in 2009 as D2426 93(2009).DOI:10.1520/D2426-93R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards
15、 volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE2The following materials have been used successfully as liquidphases(see Table 1)3:Carbowax 400,1500,1
16、540General 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 willdepend 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 colum