1、Designation: D2712 91 (Reapproved 2016)Standard Test Method forHydrocarbon Traces in Propylene Concentrates by GasChromatography1This standard is issued under the fixed designation D2712; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, 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 5 ppm to500 ppm each of ethylene, total butylenes, acety
3、lene, methylacetylene, propadiene, and butadiene in propylene concen-trates.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its us
4、e. 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.2. Referenced Documents2.1 ASTM Standards:2E260 Practice for Packed Column Gas ChromatographyF307 Practice for Samplin
5、g Pressurized Gas for Gas Analy-sis3. Summary of Test Method3.1 A relatively large volume of sample is charged to a gaspartition chromatography apparatus which has a column thatwill separate the trace hydrocarbon constituents from the majorcomponents. Any column or combination of columns may beused
6、provided they have the necessary resolution and thedetecting system has sufficient sensitivity. Several columns thathave been found satisfactory are given in 5.1.3.2 Calculation is performed by calculating the concentra-tion of the trace compound from its area relative to the area ofa standard compo
7、und of known concentration.4. Significance and Use4.1 The trace hydrocarbon compounds listed in Table 1 mayhave an effect in the commercial use of propylene concentrates,and information on their concentration is frequently necessary.5. Apparatus5.1 ColumnsAny column may be used provided it willresol
8、ve the trace compound peaks present in concentrations of20 ppm or more so that the resolution ratio, A/B, will not beless than 0.4, where A is the depth of the valley on either sideof peak B and B is the height above the baseline of the smallerof any two adjacent peaks (see Fig. 1). For compounds pr
9、esentin concentrations of less than 20 ppm the ratio A/B may be lessthan 0.4. In the case where the small-component peak isadjacent to a large one, it may be necessary to construct thebaseline of the small peak tangent to the curve as shown in Fig.2. Butylenes need not be resolved from each other. C
10、olumnsfound to be acceptable together with operating conditions usedare shown in Table 2. Table 3 shows typical retention times.5.1.1 Columns may be constructed of 3.2 mm (18 in.),6.4 mm (14 in.), or capillary tubing and usually need to be aminimum of 6 m (20 ft) in length. They usually have 20 g to
11、40 g of liquid substrate to 100 g of solid support. If packedcolumns are used, the liquid may be placed on the solid supportby any suitable method, provided the column has the desiredresolution and sensitivity.NOTE 1Separation of all the desired compounds on a single columnhas been found by cooperat
12、ors to be very difficult. Most laboratories havefound it necessary to use two or more columns. Typical instructions forpreparing such columns may be found in Practice E260.5.2 Gas ChromatographAny gas chromatography appara-tus may be used provided the system has sufficient sensitivityto detect the t
13、race compounds of interest. For calculationtechniques utilizing a recorder, the signal for 20 ppm concen-tration shall be at least 5 chart divisions above the noise levelona0to100scale chart. The noise level must be restricted toa maximum of 2 chart divisions. When electronic integration isemployed,
14、 the signal for 20 ppm concentration must be at leasttwice the noise level.NOTE 2A flame ionization detector is preferred. When using withrelatively volatile liquid phases, such as HMPA, an additional 0.31 m1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liqui
15、d Fuels, and Lubricantsand is the direct responsibility ofSubcommittee D02.D0.03 on Propylene.Current edition approved April 1, 2016. Published May 2016. Originallyapproved in 1968. Last previous edition approved in 2010 as D2712 91 (2010).DOI: 10.1520/D2712-91R16.2For referenced ASTM standards, vis
16、it 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
17、59. United States1(1 ft) section of column containing uncoated solid support will aid inreducing noise.5.3 Sample IntroductionMeans shall be provided for in-troducing a measured quantity of sample into the apparatus.Pressure sampling devices may be used to inject a smallamount of the liquid directly
18、 into the carrier gas. Introductionmay be by means of a gas valve to charge the vaporized liquid.6. Reagents and Materials6.1 Hydrocarbons, for peak identification, includingpropylene, ethylene, ethane, acetylene, methyl acetylene,propadiene, propane, 1,3-butadiene, isobutylene, 1-butene, cisand tra
19、ns 2-butene, iso- and normal butane, and cyclopropane.(WarningLiquefied petroleum gas under pressure and flam-mable.) Mixtures of these hydrocarbons may be used forcalibration provided there is no uncertainty as to the identity ofthe desired compound.6.2 Propane or Propylene, for synthetic base stoc
20、k contain-ing less than 2 ppm by weight of acetylene or 1,3-butadiene.(WarningLiquefied petroleum gas under pressure and flam-mable.)6.3 Calibration CompoundsAcetylene and 1,3-butadiene99 % minimum purity. (WarningLiquefied petroleum gasunder pressure and flammable.)6.4 Carrier GasesHelium or Nitrog
21、en. (WarningCompressed gas under pressure.)6.5 Hydrogen. (WarningCompressed gas under pressureand flammable.)6.6 Liquid Phase for ColumnSee Table 2.(WarningHexamethylphosphoramide is a potential carcinogen.)6.7 Solid SupportC22firebrick or diatomaceous earth,usually 40 to 60 or 60 to 80 mesh.6.8 Sta
22、inless Steel Sample Cylinder, 300 cm to 500 cm3capacity, capable of withstanding a minimum of 1723 kPa gage(250 psig).6.9 Silicone Rubber Septum, with suitable fittings for attach-ment to sample cylinder.6.10 Gas Syringe, 10 cm3.6.11 Vacuum Pump, capable of evacuating sample cylinderto less than 2 m
23、m Hg absolute pressure.6.12 Aluminum or Stainless Steel Tubing, 0.61 m (2 ft),3.2 mm (18 in.), or 1.6 mm (116 in.), outside diameter withfittings on one end to connect to butadiene cylinder and theother end modified so as to have an opening with an insidediameter of about 0.5 mm larger than the outs
24、ide diameter ofthe gas syringe needle.7. Sampling7.1 This section is to be followed on all samples includingunknown samples and the synthetic standards.7.2 Samples should be supplied to the laboratory in high-pressure sample cylinders, obtained using the proceduresdescribed in Practice F307 or simil
25、ar methods.7.3 Place the cylinder in a horizontal position in a safelocation such as a hood. Check to see that the container is atleast one-half full by slightly opening the valve. If liquid isemitted (a white cloud of vapors) the container is at leastone-half full. Do not analyze any samples or use
26、 any syntheticstandard if the liquid in the container is less than this amount.7.4 Place the cylinder in a vertical position and repressurizeto 1723 kPa gage (250 psig) with the chromatographic carriergas through the valve at the top of the cylinder, ensuring thatno air enters during the operation.7
27、.5 Use either of the following two procedures for obtaininga sample from the container:7.5.1 Using a Liquid ValveConnect the cylinder to theliquid valve on the chromatograph using a minimum length ofconnecting tubing, so that sample is withdrawn from thebottom of the cylinder and a liquid sample is
28、obtained. Theliquid valve on the chromatograph must be designed in such amanner that full sample pressure can be maintained through thevalve without leaking and that means are provided for trappinga liquid sample in the chromatograph valve under staticconditions of flow. With the exit of the chromat
29、ograph valveclosed open the valve on the cylinder. Slowly open the exitfrom the chromatograph valve so that liquid flows through theconnecting line and valve. Close the exits so that the liquidTABLE 1 Molecular Weight and Specific GravityCompound Molecular Weight Specific Gravity, 60/60Propylene 42.
30、08 0.5220Propane 44.09 0.5077FIG. 1 Illustration of A/B RatioFIG. 2 Illustration of A/B Ratio for Small-Component PeakD2712 91 (2016)2sample is trapped in the valve. Perform the necessary opera-tions to introduce the liquid sample into the chromatographcolumn.7.5.2 Vaporized SampleAssemble the appar
31、atus similar tothat illustrated in Fig. 3. Disconnect the 1700 cm3cylinder at Eand evacuate. Close valve B and open valves C and D, allowingthe liquid sample to flow into the small cylinder. Slowly openvalve B and allow the sample to flow through until a steadyslow stream of liquid emerges from B. C
32、lose valves B, C, andD in that order, trapping a portion of the liquid sample in thepipe cylinder (Note 4). Attach the evacuated cylinder(1700 cm3volume) at E. Open valve A and then valve B. TheTABLE 2 Typical Column ConditionsColumn 1 2 345678910 1Column: SeriesASeriesMixed20TCEPMixed80 MEEE Series
33、Liquid DMS Squa DMS ODPN UCON DMS None 80 %SE-30ODPN n C16HMPA 8 DIDP None DMS SquaWeight,% 3 2 U 15 1515 2525203020 3320Solid Chrom Chrom Chrom Chrom Chrom Chrom SiGel Chrom Chrom Chrom Chrom Chrom SiGel Chrom ChromMesh 60 to 80 60 to 80 100 80 to 100 U 60 to 80 U 30 to 60 30 to 60 60 to 80 60 to 8
34、0 60 to 80 40 to 60 60 to 80 60 to 80Treatment none none U U U U U AW AW AW AW none FeCl none noneLength, ft 4 30 22 20 8 16 3.5 50 50 20 20 25 15 8 35Inside diameter, 0.19 0.13 0.085 0.085 0.085 0.085 0.18 0.19 0.19 0.085 0.085 0.085 0.19 0.085 0.085in.Temperature:Inlet, C RT RT RT RT 160 70 RT RT
35、RT RT RTDetector, C 150 RT 50 50 175 70 RT RT RT RT RTColumn, C RT RT 50 50 30 70 RT RT RT RT RTSample:InjectionGas, cm3SplitGV0.5GV0.2GV1GV0.7Syr3.0Syr1GV0.5GV540:1GV0.4GV0.4GV1Carrier:Gascm3/minHe50He22He24He42He40He40H217He60He30He30He52Detector:TypeVoltageFI TC8FI TC12FI TC70FI FI FI FI FIRecord
36、er:Range, mV 1 1 51115511 1in./h 30 60 30 30 30 30 30 30 60 60 30Measurement Tri Plan Plan Plan PH PH PH PW/2 Tri Tri TriAbbreviations:AW Acid washed ODPN ,-oxydipropionitrileChrom “Chromosorb” P (trademark of Johns-Manville Products Corp.) PH Peak heightDIDP Diisodecyl phthalate Plan PlanimeterDMS
37、2,4-dimethyl sulfolane PW/2 Peak height width at13 heightFeCl Ferric chloride, modified RT Room temperatureFI Flame ionization SE-30 SE-30 gum rubberGV Gas valve SiGel Silica gelHe Helium Squa SqualaneH2Hydrogen Syr SyringeHMPA Hexamethyl phosphoramide TC Thermal conductivityMEEE Bis-2(methoxy ethox
38、y ethyl) ether TCEP 1,3-tris(2-cyano ethoxy)propanen C16Normal hexadecane Tri TriangulationU UnknownADetector bypassed during major peaks.TABLE 3 Typical Retention Time, MinColumn 1 23456 78 9 10 1Acetylene 10.1 . . . . 6.5 2.2 22.3 . . 8.01,3-Butadiene 39.4 24.9 . . 15.3 . . 20.8 17.4 . 35.1Isobute
39、ne 33.3 . 8.7 . . 15.7 . 11.0 10.9 . 29.71-Butene 33.3 . 9.5 . . 15.7 . 11.4 10.9 . 29.7trans-2-Butene 42.1 . 11.8 . . 18.1 . 13.1 12.9 . 38.0Acis-2-Butene 46.9 . 14.2 . . 20.5 . 15.1 14.8 . 42.8Cyclopropane 22.8 . . . . 12.0 7.2 8.3 . . .Ethylene 8.1 . . 5.1 . 5.8 2.3 . . 3.6 5.7Methyl acetylene 24
40、.2 26.1 . . 18.3 . . 28.0 16.4 . 21.1Neopentane 34.3B. . . . . 15.4 8.8 . . .Propadiene 20.6 . 10.2 . . 11.3 . . 10.0 . 17.6ADMS portion only.BSqualane portion only.D2712 91 (2016)3liquid will expand, filling the larger cylinder and give a gagepressure of approximately 55 kPa (8 psi) for propylene c
41、on-centrates. Close valve A and disconnect at E.NOTE 3To avoid possible rupture of the liquid-filled pipe cylinder, thesample cylinder and its contents should be at room temperature prior tosampling and the liquid should be allowed to remain in the pipe cylinderfor only a minimum amount of time.7.5.
42、2.1 Connect the cylinder containing the vaporizedsample to the chromatograph gas valve. Evacuate the sampleloop and the lines up to the sample cylinder. Close the valve tothe vacuum source and allow the sample loop to fill withsample up to atmospheric pressure. Repeat the evacuation andfilling of th
43、e sample loop with vaporized sample. Turn thevalve so that the vaporized sample is displaced with carrier gasinto the chromatograph.8. Calibration8.1 Select the conditions of column temperature and carriergas flow that will give the prescribed separation.8.2 Determine the retention time for each com
44、pound byinjecting small amounts of the compound either separately orin a mixture using the same method of charging as is used forthe sample.9. Synthetic Standard9.1 Connect the silicone septum to a valve of the stainlesssteel sample cylinder in such a manner that the volumebetween the septum and the
45、 valve is less than 1 % of the totalvolume of the cylinder. By means of suitable fittings connectthe other valve of the cylinder to a vacuum pump and evacuatethe cylinder and space between the cylinder valve and septum.Close the valves, disconnect the cylinder from the vacuumpump, and weigh the empt
46、y cylinder on a suitable platformbalance to the nearest 1 g.9.2 Connect the tubing to the 1,3-butadiene cylinder andcrack the valve on this cylinder so that there is a constant flowof vapors from the end of the tubing which must be at roomtemperature. Insert the syringe into the end of the tubing an
47、dslowly withdraw 5 cm3of the butadiene vapors. Flush thesyringe three times with vapors and inject exactly 5 cm3of thevapor through the septum into the evacuated cylinder. Closethe valve between the cylinder and the septum. Inject 5 cm3ofacetylene to the evacuated cylinder in the same manner.9.3 Fil
48、l another cylinder of the same size with propane orpropylene base stock. Establish outage in the base stockcylinder by removing 25 % of the liquid contents. Place thecylinder containing the blend stock in a vertical position so thatthe bottom valve is above the top of the cylinder containing thebuta
49、diene. If the cylinder containing the base stock is equippedwith a dip pipe be sure that this valve is at the top. Connect thebottom valve of the base stock cylinder to the other cylinder bymeans of suitable tubing capable of withstanding 1723 kPa(250 psi) pressure. Flush the connecting line with base stockbefore tightening connections to the evacuated cylinder. Coolthe evacuated cylinder to a temperature of 11 C to 17 C(20 F to 30 F) below that of the base stock. Open the valvesFIG. 3 Sampling and Expansion Cylinder ArrangementD2712 91 (2016)4
