ASTM D5580-2002 Standard Test Method for Determination of Benzene Toluene Ethylbenzene p m-Xylene o-Xylene C9 and Heavier Aromatics and Total Aromatics in Finished Gasoline by Gas .pdf

1、Designation: D 5580 02An American National StandardStandard Test Method forDetermination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9and Heavier Aromatics, and TotalAromatics in Finished Gasoline by Gas Chromatography1This standard is issued under the fixed designation D 5580; the num

2、ber 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 (e) indicates an editorial change since the last revision or reapproval.1. Scop

3、e1.1 This test method covers the determination of benzene,toluene, ethylbenzene, the xylenes, C9and heavier aromatics,and total aromatics in finished motor gasoline by gas chroma-tography.1.2 The aromatic hydrocarbons are separated without inter-ferences from other hydrocarbons in finished gasoline.

4、 Non-aromatic hydrocarbons having a boiling point greater thann-dodecane may cause interferences with the determination ofthe C9and heavier aromatics. For the C8aromatics, p-xyleneand m-xylene co-elute while ethylbenzene and o-xylene areseparated. The C9and heavier aromatics are determined as asingl

5、e group.1.3 This test method covers the following concentrationranges, in liquid volume %, for the preceding aromatics:benzene, 0.1 to 5 %; toluene, 1 to 15 %; individual C8aromatics, 0.5 to 10 %; total C9and heavier aromatics, 5 to30 %, and total aromatics, 10 to 80 %.1.4 Results are reported to th

6、e nearest 0.01 % by either massor by liquid volume.1.5 Many of the common alcohols and ethers that are addedto gasoline to reduce carbon monoxide emissions and increaseoctane, do not interfere with the analysis. Ethers such as methyltert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmeth

7、ylether (TAME), and diisopropylether (DIPE) havebeen found to elute from the precolumn with the nonaromatichydrocarbons to vent. Other oxygenates, including methanoland ethanol elute before benzene and the aromatic hydrocar-bons. 1-Methylcyclopentene has also been found to elute fromthe precolumn to

8、 vent and does not interfere with benzene.1.6 The values stated in SI units are to be regarded asstandard. The values given in parentheses are provided forinformation only; they may not be exact equivalents.1.7 This standard does not purport to address all of thesafety concerns, if any, associated w

9、ith 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:D 1298 Test Method for Density, Relative Density, (SpecificGravity

10、) or API Gravity of Crude Petroleum and LiquidPetroleum Products by Hydrometer Method2D 4052 Test Method for Density and Relative Density ofLiquids by Digital Density Meter3D 4057 Practice for Manual Sampling of Petroleum andPetroleum Products3D 4307 Practice for Preparation of Liquid Blends for Use

11、 asAnalytical Standards3E 355 Practice for Gas Chromatography Terms and Rela-tionships43. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 aromaticany organic compound containing a ben-zene ring.3.1.2 low-volume connectora special union for connect-ing two lengths of narrow bore t

12、ubing 1.6-mm (0.06-in.)outside diameter and smaller; sometimes this is referred to aszero dead volume union.3.1.3 narrow bore tubingtubing used to transfer compo-nents prior to or after separation; usually 0.5-mm (0.02-in.)inside diameter and smaller.3.1.4 split ratioin capillary gas chromatography,

13、 the ratioof the total flow of carrier gas to the sample inlet versus theflow of the carrier gas to the capillary column, expressed by:split ratio 5 S 1 C!/C (1)where:S = flow rate at the splitter vent andC = flow rate at the column outlet.3.1.5 1,2,3-tris-2-cyanoethoxypropane (TCEP)a polar gaschrom

14、atographic liquid phase.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0L on Gas Chromatography.Current edition approved Jan. 10, 2002. Published March 2002. Originallypublished as D 5580 94

15、. Last previous edition D 5580 00.2Annual Book of ASTM Standards, Vol 05.01.3Annual Book of ASTM Standards, Vol 05.02.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 wall-coated open tu

16、bular (WCOT)a type of capil-lary column prepared by coating the inside wall of the capillarywith a thin film of stationary phase.4. Summary of Test Method4.1 A two-column chromatographic system equipped with acolumn switching valve and a flame ionization detector is used.A reproducible volume of sam

17、ple containing an appropriateinternal standard such as 2-hexanone is injected onto a precol-umn containing a polar liquid phase (TCEP). The C9andlighter nonaromatics are vented to the atmosphere as they elutefrom the precolumn. A thermal conductivity detector may beused to monitor this separation. T

18、he TCEP precolumn isbackflushed immediately before the elution of benzene, and theremaining portion of the sample is directed onto a secondcolumn containing a nonpolar liquid phase (WCOT). Benzene,toluene, and the internal standard elute in the order of theirboiling points and are detected by a flam

19、e ionization detector.Immediately after the elution of the internal standard, the flowthrough the nonpolar WCOT column is reversed to backflushthe remainder of the sample (C8and heavier aromatics plus C10and heavier nonaromatics) from the column to the flameionization detector.4.2 The analysis is re

20、peated a second time allowing the C12and lighter nonaromatics, benzene and toluene to elute fromthe polar TCEP precolumn to vent. A thermal conductivitydetector may be used to monitor this separation. The TCEPprecolumn is backflushed immediately prior to the elution ofethylbenzene and the remaining

21、aromatic portion is directedinto the WCOT column. The internal standard and C8aromaticcomponents elute in the order of their boiling points and aredetected by a flame ionization detector. Immediately aftero-xylene has eluted, the flow through the nonpolar WCOTcolumn is reversed to backflush the C9an

22、d heavier aromatics tothe flame ionization detector.4.3 From the first analysis, the peak areas of benzene,toluene, and the internal standard (2-hexanone) are measuredand recorded. Peak areas for ethylbenzene, p/m-xylene,o-xylene, the C9and heavier aromatics, and internal standardare measured and re

23、corded from the second analysis. Thebackflush peak eluting from the WCOT column in the secondanalysis contains only C9and heavier aromatics.4.4 The flame ionization detector response, proportional tothe concentration of each component, is used to calculate theamount of aromatics that are present wit

24、h reference to theinternal standard.5. Significance and Use5.1 Regulations limiting the concentration of benzene andthe total aromatic content of finished gasoline have beenestablished for 1995 and beyond in order to reduce the ozonereactivity and toxicity of automotive evaporative and exhaustemissi

25、ons. Test methods to determine benzene and the aromaticcontent of gasoline are necessary to assess product quality andto meet new fuel regulations.5.2 This test method can be used for gasolines that containoxygenates (alcohols and ethers) as additives. It has beendetermined that the common oxygenate

26、s found in finishedgasoline do not interfere with the analysis of benzene and otheraromatics by this test method.6. Apparatus6.1 Chromatographic SystemSee Practice E 355 for spe-cific designations and definitions. Refer to Fig. 1 for a diagramof the system.6.1.1 Gas Chromatograph (GC), capable of op

27、erating at theconditions given in Table 1, and having a column switchingand backflushing system equivalent to Fig. 1. Carrier gaspressure and flow control devices shall be capable of precisecontrol when column head pressures and flow rates are low.6.1.2 Sample Introduction System, capable of introdu

28、cing arepresentative sample into the gas chromatographic inlet.Microlitre syringes and automatic syringe injectors have beenused successfully.6.1.3 Inlet System, (splitting type) Split injection is nec-essary to maintain the actual chromatographed sample sizewithin the limits required for optimum co

29、lumn efficiency anddetector linearity.6.1.3.1 Some gas chromatographs are equipped with on-column injectors and autosamplers which can inject submi-crolitre sample sizes. Such systems can be used provided thatcolumn efficiency and detector linearity are comparable tosystems with split injection.FIG.

30、 1 Valve Diagram, Aromatics in GasolineD 558026.1.4 DetectorA flame ionization detector (Detector A) isemployed for quantitation of components eluting from theWCOT column. The flame ionization detector used for Detec-tor A shall have sufficient sensitivity and stability to detect 0.01volume % of an

31、aromatic compound.6.1.4.1 It is strongly recommended that a thermal conduc-tivity detector be placed on the vent of the TCEP precolumn(Detector B). This facilitates the determination of valveBACKFLUSH and RESET times (10.5) and is useful formonitoring the separation of the polar TCEP precolumn.6.1.5

32、 Switching and Backflushing Valve, to be located withina temperature-controlled heated zone and capable of perform-ing the functions in accordance with Section 10, and illustratedin Fig. 1. The valve shall be of low internalvolume design andnot contribute significantly to deterioration of chromatogr

33、aphicresolution.6.1.5.1 A 10-port valve with 1.6-mm (0.06) outside diam-eter fittings is recommended for this test method. Alternately,and if using columns of 0.32-mm inside diameter or smaller, avalve with 0.8-mm (0.03-in.) outside diameter fittings shouldbe used.6.1.5.2 Some gas chromatographs are

34、 equipped with anauxiliary oven which can be used to contain the valve. In sucha configuration, the valve can be kept at a higher temperaturethan the polar and nonpolar columns to prevent samplecondensation and peak broadening. The columns are thenlocated in the main oven and the temperature can be

35、adjustedfor optimum aromatic resolution.6.1.5.3 An automatic valve switching device is stronglyrecommended to ensure repeatable switching times.6.2 Data Acquisition System:6.2.1 Integrator or Computer, capable of providing real-time graphic and digital presentation of the chromatographicdata are rec

36、ommended for use. Peak areas and retention timescan be measured by computer or electronic integration.6.2.1.1 It is recommended that this device be capable ofperforming multilevel internal-standard-type calibrations andbe able to calculate the correlation coefficient (r2) and linearleast square fit

37、equation for each calibration data set inaccordance with 11.4.6.3 Chromatographic Columns (two columns are used):6.3.1 Polar Precolumn, to perform a pre-separation of thearomatics from nonaromatic hydrocarbons in the same boilingpoint range. Any column with equivalent or better chromato-graphic effi

38、ciency and selectivity in accordance with 6.3.1.1can be used.6.3.1.1 TCEP Micro-Packed Column, 560-mm (22-in.) by1.6-mm (116-in.) outside diameter by 0.76-mm (0.030-in.)inside diameter stainless steel tube packed with 0.14 to 0.15 gof 20 % (mass/mass) TCEP on 80/100 mesh ChromosorbP(AW). This column

39、 was used in the cooperative study toprovide the precision and bias data referred to in Section 15.6.3.2 Nonpolar (Analytical) ColumnAny column withequivalent or better chromatographic efficiency and selectivityin accordance with 6.3.2.1 can be used.6.3.2.1 WCOT Methyl Silicone Column, 30 m long by0

40、.53-mm inside diameter fused silica WCOT column with a5.0-m film thickness of cross-linked methyl siloxane.7. Reagents and Materials7.1 Carrier Gas, appropriate to the type of detector used.Helium has been used successfully. The minimum purity of thecarrier gas used must be 99.95 mol %. Additional p

41、urificationmay be necessary to remove trace amounts of oxygen.(WarningHelium is usually supplied as a compressed gasunder high pressure.)7.2 Methylene ChlorideUsed for column preparation. Re-agent grade, free of nonvolatile residue. (WarningHarmfulwhen ingested or inhaled at high concentrations.)7.3

42、 2,2,4-Trimethylpentane (isooctane) Used as a solventin the preparation of the calibration mixture. Reagent grade.(WarningIsooctane is flammable and can be harmful or fatalwhen ingested or inhaled.7.4 Standards for Calibration and Identification, requiredfor all components to be analyzed and the int

43、ernal standard.Standards are used for establishing identification by retentiontime as well as calibration for quantitative measurements.These materials shall be of known purity and free of the othercomponents to be analyzed. (WarningThese materials areflammable and may be harmful or fatal when inges

44、ted orinhaled.8. Preparation of Columns8.1 TCEP Column Packing:8.1.1 Use any satisfactory method, that will produce acolumn capable of retaining aromatics from nonaromaticcomponents of the same boiling point range in a gasolinesample. The following procedure has been used successfully.8.1.2 Complete

45、ly dissolve 10 g of TCEP in 100 mL ofmethylene chloride. Next add 40 g of 80/100 mesh Chro-mosorb P(AW) to the TCEP solution. Quickly transfer thismixture to a drying dish, in a fume hood, without scraping anyof the residual packing from the sides of the container.Constantly, but gently, stir the pa

46、cking until all of the solventhas evaporated. This column packing can be used immediatelyto prepare the TCEP column.TABLE 1 Typical Chromatographic Operating Parameters 130TemperaturesInjection port (split injector) 200CFID (Detector A) 250CTCD (Detector B) 200CNonpolar WCOT capillaryInitial 60C (6

47、min)Program rate 2C/minFinal 115C (hold until allcomponents elute)Polar TCEP precolumn (temperature toremain constant before time toBACKFLUSH, T1 or T2. Do not exceedmaximum operating temperature.)60C or same as nonpolar WCOTcapillary if TCEP/WCOT columnscontained in identical heated zone.Valve 115C

48、 or same as nonpolar WCOTcapillary if valve and WCOT columncontained in identical heated zone.Flows and ConditionsCarrier gas heliumFlow to TCEP precolumn (split injector) 10 mL/minFlow to WCOT capillary (auxiliary flow) 10 mL/minFlow from split vent 100 mL/minDetector gases as necessarySplit ratio

49、11:1Sample size 1 LD 558038.2 Micro-packed TCEP Column:8.2.1 Wash a straight 560-mm (22-in.) length of 1.6-mm(116-in.) outside diameter, 0.76-mm (0.030-in.) inside diameterstainless steel tubing with methanol and dry with compressednitrogen.8.2.2 Insert 6 to 12 strands of silvered wire, a small meshscreen or stainless steel frit inside one end of the tube. Slowlyadd 0.14 to 0.15 g of packing material to the column and gentlyvibrate to settle the packing inside the column. Insert silveredwire, mesh screen, or frit to the other end of the tube to preventthe p