1、Designation: D 5580 02 (Reapproved 2007)An 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 designati
2、on D 5580; 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 (e) indicates an editorial change since the last revision or
3、reapproval.1. Scope1.1 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
4、finished gasoline. 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 de
5、termined as asingle 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
6、are reported to the 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 (ET
7、BE), tert-amylmethylether (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 fr
8、omthe precolumn to vent and does not interfere with benzene.1.6 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the
9、responsibility 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:2D 1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of C
10、rude Petroleum and LiquidPetroleum Products by Hydrometer MethodD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density MeterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4307 Practice for Preparation of Liquid Blends for Use asAnalytical StandardsE
11、 355 Practice for Gas Chromatography Terms and Rela-tionships3. 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 tubing 1.6-mm (0.06-in.)out
12、side diameter and smaller; sometimes this is referred to aszero dead volume union.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 Methods.Current edition approved Nov
13、. 1, 2007. Published January 2008. Originallyapproved in 1994. Last previous edition approved in 2002 as D 558002.2For 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 th
14、e standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Copyright by ASTM Intl (all rights reserved); Sun Jan 4 01:22:25 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License A
15、greement. No further reproductions authorized.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, the ratioof the total flow of carrier gas to the sample inlet
16、 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 gaschromatographic liquid phase.3.1.6 wall-coated open tubular (WCOT)a
17、 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 sample containin
18、g 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. The TCEP preco
19、lumn 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 flame ionization
20、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 repeated a seco
21、nd 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 aromatic port
22、ion 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 C9and heavier aro
23、matics 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 recorded from t
24、he 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 with reference t
25、o 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 exhaustemissions. Test met
26、hods 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 oxygenates found in fi
27、nishedgasoline 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 operating at th
28、econditions 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.FIG. 1 Valve Diagram, Aromatics in GasolineD 5580 02 (2007)2Copyr
29、ight by ASTM Intl (all rights reserved); Sun Jan 4 01:22:25 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.6.1.2 Sample Introduction System, capable of introducing arepresentative sample into the gas chromatographic inlet.Microlitre s
30、yringes 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 column efficiency anddetector linearity.6.1.3.1 Some gas chromatographs are e
31、quipped 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.6.1.4 DetectorA flame ionization detector (Detector A) isemployed for quantitat
32、ion of components eluting from theWCOT column. The flame ionization detector used for Detec-torAshall have sufficient sensitivity and stability to detect 0.01volume % of an aromatic compound.6.1.4.1 It is strongly recommended that a thermal conduc-tivity detector be placed on the vent of the TCEP pr
33、ecolumn(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 Switching and Backflushing Valve, to be located withina temperature-controlled heated zone and capable of perform-ing the func
34、tions in accordance with Section 10, and illustratedin Fig. 1. The valve shall be of low internalvolume design andnot contribute significantly to deterioration of chromatographicresolution.6.1.5.1 A 10-port valve with 1.6-mm (0.06) outside diam-eter fittings is recommended for this test method. Alte
35、rnately,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 equipped with anauxiliary oven which can be used to contain the valve. In sucha configuration, the valve can be kept at a high
36、er 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 adjustedfor optimum aromatic resolution.6.1.5.3 An automatic valve switching device is stronglyrecommended to ensure repeatable
37、 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 recommended for use. Peak areas and retention timescan be measured by computer or electronic integration.6.2.1.1 It is recommended
38、 that this device be capable ofperforming multilevel internal-standard-type calibrations andbe able to calculate the correlation coefficient (r2) and linearleast square fit equation for each calibration data set inaccordance with 11.4.6.3 Chromatographic Columns (two columns are used):6.3.1 Polar Pr
39、ecolumn, to perform a pre-separation of thearomatics from nonaromatic hydrocarbons in the same boilingpoint range. Any column with equivalent or better chromato-graphic efficiency 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
40、.) 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 was used in the cooperative study toprovide the precision and bias data referred to in Section 15.6.3.2 Nonpolar (Analytical)
41、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 by0.53-mm inside diameter fused silica WCOT column with a5.0-m film thickness of cross-linked methyl siloxane.7. Reagents and Mate
42、rials7.1 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 purificationmay be necessary to remove trace amounts of oxygen.(WarningHelium is usually supplied as a compressed gasunder high
43、pressure.)7.2 Methylene ChlorideUsed for column preparation. Re-agent grade, free of nonvolatile residue. (WarningHarmfulwhen ingested or inhaled at high concentrations.)7.3 2,2,4-Trimethylpentane (isooctane) Used as a solventin the preparation of the calibration mixture. Reagent grade.(WarningIsooc
44、tane 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 internal standard.Standards are used for establishing identification by retentiontime as well as calibration for quantitative meas
45、urements.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 ingested orinhaled.TABLE 1 Typical Chromatographic Operating Parameters 130TemperaturesInjection port (split injector) 200CFID (Dete
46、ctor A) 250CTCD (Detector B) 200CNonpolar WCOT capillaryInitial 60C (6 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 WCOTcapi
47、llary if TCEP/WCOT columnscontained in identical heated zone.Valve 115C 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/mi
48、nFlow from split vent 100 mL/minDetector gases as necessarySplit ratio 11:1Sample size 1 LD 5580 02 (2007)3Copyright by ASTM Intl (all rights reserved); Sun Jan 4 01:22:25 EST 2009Downloaded/printed byGuo Dehua (CNIS) pursuant to License Agreement. No further reproductions authorized.8. Preparation
49、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 Completely 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
