ASTM_D_2712_-_91_2010.pdf

Designation:D271291(Reapproved 2010)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 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 5 to 500ppm each of ethylene,total butylenes,acetylene,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 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.2.Referenced Documents2.1 ASTM Standards:2E260 Practice for Packed Column Gas ChromatographyF307 Practice for Sampling 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 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 compound 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 willresolve 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 presentin 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.Columnsfound 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 to 40g 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.NOTE1Separation of all the desired compounds on a single columnhas been found by cooperators 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 trace 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 levelon a 0 to 100 scale chart.The noise level must be restricted toa maximum of 2 chart divisions.When electronic integration isemployed,the signal for 20-ppm concentration must be at leasttwice the noise level.NOTE2A 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,Liquid Fuels,and Lubricantsand is the direct responsibility ofSubcommittee D02.D0.03 on Propylene.Current edition approved May 1,2010.Published May 2010.Originallyapproved in 1968.Last previous edition approved in 2003 as D2712 91(2003)E1.DOI:10.1520/D2712-91R10.2For referenced ASTM standards,visit 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 19428-2959.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