1、Designation: D5580 02 (Reapproved 2007)D5580 13Standard Test Method forDetermination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, and TotalAromatics in Finished Gasoline by Gas Chromatography1This standard is issued under the fixed designation D5580; the number
2、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. Scope Sco
3、pe*1.1 This test method covers the determination of benzene, toluene, ethylbenzene, the xylenes, C9 and heavier aromatics, andtotal aromatics in finished motor gasoline by gas chromatography.1.2 The aromatic hydrocarbons are separated without interferences from other hydrocarbons in finished gasolin
4、e. Nonaromatichydrocarbons having a boiling point greater than n-dodecane may cause interferences with the determination of the C9 and heavieraromatics. For the C8 aromatics, p-xylene and m-xylene co-elute while ethylbenzene and o-xylene are separated. The C9 andheavier aromatics are determined as a
5、 single group.1.3 This test method covers the following concentration ranges, in liquid volume %, for the preceding aromatics: benzene, 0.1to 5 %; toluene, 1 to 15 %; individual C8 aromatics, 0.5 to 10 %; total C9 and heavier aromatics, 5 to 30 %, and total aromatics,10 to 80 %.1.4 Results are repor
6、ted to the nearest 0.01 % by either mass or by liquid volume.1.5 Many of the common alcohols and ethers that are added to gasoline to reduce carbon monoxide emissions and increaseoctane, do not interfere with the analysis. Ethers such as methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE),te
7、rt-amylmethylether (TAME), and diisopropylether (DIPE) have been found to elute from the precolumn with the nonaromatichydrocarbons to vent. Other oxygenates, including methanol and ethanol elute before benzene and the aromatic hydrocarbons.1-Methylcyclopentene has also been found to elute from the
8、precolumn to vent and does not interfere with benzene.1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.04.0L on Gas Chromatography Methods.Current edition approved Nov.
9、1, 2007Sept. 15, 2013. Published January 2008 October 2013. Originally approved in 1994. Last previous edition approved in 20022007as D5580D5580 02 (2007).02. DOI: 10.1520/D5580-02R07.10.1520/D5580-13.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard
10、an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is
11、to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.6 The values stated in SI units are to be regarded as standard. The values given
12、 in parentheses are for information only.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryl
13、imitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density MeterD
14、4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsE355 Practice for Gas Chromatography Terms and Relationships3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 aromaticany organic c
15、ompound containing a benzene ring.3.1.2 low-volume connectora special union for connecting two lengths of narrow bore tubing 1.6-mm (0.06-in.) outsidediameter and smaller; sometimes this is referred to as zero dead volume union.3.1.3 narrow bore tubingtubing used to transfer components prior to or a
16、fter separation; usually 0.5-mm (0.02-in.) insidediameter and smaller.3.1.4 split ratioin capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flowof the carrier gas to the capillary column, expressed by:split ratio5S1C!/C (1)where:S = flow rate at
17、the splitter vent andC = flow rate at the column outlet.3.1.5 1,2,3-tris-2-cyanoethoxypropane (TCEP)a polar gas chromatographic liquid phase.3.1.6 wall-coated open tubular (WCOT)a type of capillary column prepared by coating the inside wall of the capillary witha thin film of stationary phase.4. Sum
18、mary of Test Method4.1 A two-column chromatographic system equipped with a column switching valve and a flame ionization detector is used. Areproducible volume of sample containing an appropriate internal standard such as 2-hexanone is injected onto a precolumncontaining a polar liquid phase (TCEP).
19、 The C9 and lighter nonaromatics are vented to the atmosphere as they elute from theprecolumn. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn is backflushedimmediately before the elution of benzene, and the remaining portion of the sample is directed onto
20、a second column containinga nonpolar liquid phase (WCOT). Benzene, toluene, and the internal standard elute in the order of their boiling points and aredetected by a flame ionization detector. Immediately after the elution of the internal standard, the flow through the nonpolar WCOTcolumn is reverse
21、d to backflush the remainder of the sample (C8 and heavier aromatics plus C10 and heavier nonaromatics) fromthe column to the flame ionization detector.4.2 The analysis is repeated a second time allowing the C12 and lighter nonaromatics, benzene and toluene to elute from thepolar TCEP precolumn to v
22、ent. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn isbackflushed immediately prior to the elution of ethylbenzene and the remaining aromatic portion is directed into the WCOTcolumn. The internal standard and C8 aromatic components elute in the order of th
23、eir boiling points and are detected by a flameionization detector. Immediately after o-xylene has eluted, the flow through the nonpolar WCOT column is reversed to backflushthe C9 and heavier aromatics to the flame ionization detector.4.3 From the first analysis, the peak areas of benzene, toluene, a
24、nd the internal standard (2-hexanone) are measured andrecorded. Peak areas for ethylbenzene, p/m-xylene, o-xylene, the C9 and heavier aromatics, and internal standard are measured andrecorded from the second analysis. The backflush peak eluting from the WCOT column in the second analysis contains on
25、ly C9and heavier aromatics.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.D5580 1324.4 The flame ionization
26、detector response, proportional to the concentration of each component, is used to calculate the amountof aromatics that are present with reference to the internal standard.5. Significance and Use5.1 Regulations limiting the concentration of benzene and the total aromatic content of finished gasolin
27、e have been establishedfor 1995 and beyond in order to reduce the ozone reactivity and toxicity of automotive evaporative and exhaust emissions. Testmethods to determine benzene and the aromatic content of gasoline are necessary to assess product quality and to meet new fuelregulations.5.2 This test
28、 method can be used for gasolines that contain oxygenates (alcohols and ethers) as additives. It has been determinedthat the common oxygenates found in finished gasoline do not interfere with the analysis of benzene and other aromatics by thistest method.6. Apparatus6.1 Chromatographic SystemSee Pra
29、ctice E355 for specific designations and definitions. Refer to Fig. 1 for a diagram of thesystem.6.1.1 Gas Chromatograph (GC), capable of operating at the conditions given in Table 1, and having a column switching andbackflushing system equivalent to Fig. 1. Carrier gas pressure and flow control dev
30、ices shall be capable of precise control whencolumn head pressures and flow rates are low.6.1.2 Sample Introduction System, capable of introducing a representative sample into the gas chromatographic inlet. Microlitresyringes and automatic syringe injectors have been used successfully.6.1.3 Inlet Sy
31、stem, (splitting type)Split injection is necessary to maintain the actual chromatographed sample size within thelimits required for optimum column efficiency and detector linearity.6.1.3.1 Some gas chromatographs are equipped with on-column injectors and autosamplers which can inject submicrolitresa
32、mple sizes. Such systems can be used provided that column efficiency and detector linearity are comparable to systems with splitinjection.6.1.4 DetectorA flame ionization detector (Detector A) is employed for quantitation of components eluting from the WCOTcolumn. The flame ionization detector used
33、for Detector A shall have sufficient sensitivity and stability to detect 0.01 volume %of an aromatic compound.6.1.4.1 It is strongly recommended that a thermal conductivity detector be placed on the vent of the TCEP precolumn (DetectorB). This facilitates the determination of valve BACKFLUSH and RES
34、ET times (10.5) and is useful for monitoring the separationof the polar TCEP precolumn.6.1.5 Switching and Backflushing Valve, to be located within a temperature-controlled heated zone and capable of performingthe functions in accordance with Section 10, and illustrated in Fig. 1. The valve shall be
35、 of low internalvolume design and notcontribute significantly to deterioration of chromatographic resolution.6.1.5.1 A 10-port valve with 1.6-mm (0.06) outside diameter fittings is recommended for this test method. Alternately, and ifusing columns of 0.32-mm inside diameter or smaller, a valve with
36、0.8-mm (0.03-in.) outside diameter fittings should be used.6.1.5.2 Some gas chromatographs are equipped with an auxiliary oven which can be used to contain the valve. In such aconfiguration, the valve can be kept at a higher temperature than the polar and nonpolar columns to prevent sample condensat
37、ionand peak broadening. The columns are then located in the main oven and the temperature can be adjusted for optimum aromaticresolution.6.1.5.3 An automatic valve switching device is strongly recommended to ensure repeatable switching times.6.2 Data Acquisition System:FIG. 1 Valve Diagram, Aromatic
38、s in GasolineD5580 1336.2.1 Integrator or Computer, capable of providing real-time graphic and digital presentation of the chromatographic data arerecommended for use. Peak areas and retention times can be measured by computer or electronic integration.6.2.1.1 It is recommended that this device be c
39、apable of performing multilevel internal-standard-type calibrations and be ableto calculate the correlation coefficient (r2) and linear least square fit equation for each calibration data set in accordance with 11.4.6.3 Chromatographic Columns (two columns are used):6.3.1 Polar Precolumn, to perform
40、 a pre-separation of the aromatics from nonaromatic hydrocarbons in the same boiling pointrange. Any column with equivalent or better chromatographic efficiency and selectivity in accordance with 6.3.1.1 can be used.6.3.1.1 TCEP Micro-Packed Column, 560-mm (22-in.) by 1.6-mm (116-in.) outside diamet
41、er by 0.76-mm (0.030-in.) insidediameter stainless steel tube packed with 0.14 to 0.15 g of 20 % (mass/mass) TCEP on 80/100 mesh Chromosorb P(AW). Thiscolumn was used in the cooperative study to provide the precision and bias data referred to in Section 15.6.3.2 Nonpolar (Analytical) ColumnAny colum
42、n with equivalent or better chromatographic efficiency and selectivity inaccordance with 6.3.2.1 can be used.6.3.2.1 WCOT Methyl Silicone Column, 30 m long by 0.53-mm inside diameter fused silica WCOT column with a 5.0-m filmthickness of cross-linked methyl siloxane.7. Reagents and Materials7.1 Carr
43、ier Gas, appropriate to the type of detector used. Helium has been used successfully. The minimum purity of the carriergas used must be 99.95 mol %.Additional purification may be necessary to remove trace amounts of oxygen. (WarningHeliumis usually supplied as a compressed gas under high pressure.)7
44、.2 Methylene ChlorideUsed for column preparation. Reagent grade, free of nonvolatile residue. (WarningHarmful wheningested or inhaled at high concentrations.)7.3 2,2,4-Trimethylpentane (isooctane)Used as a solvent in the preparation of the calibration mixture. Reagent grade.(WarningIsooctane is flam
45、mable and can be harmful or fatal when ingested or inhaled.7.4 Standards for Calibration and Identification, required for all components to be analyzed and the internal standard. Standardsare used for establishing identification by retention time as well as calibration for quantitative measurements.
46、 These materials shallbe of known purity and free of the other components to be analyzed. (WarningThese materials are flammable and may beharmful or fatal when ingested or inhaled.TABLE 1 Typical Chromatographic Operating Parameters 130TemperaturesInjection port (split injector) 200CFID (Detector A)
47、 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 WCOTcapillary i
48、f 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/minFlow f
49、rom split vent 100 mL/minDetector gases as necessarySplit ratio 11:1Sample size 1 LD5580 1348. Preparation of Columns8.1 TCEP Column Packing:8.1.1 Use any satisfactory method, that will produce a column capable of retaining aromatics from nonaromatic components ofthe same boiling point range in a gasoline sample. The following procedure has been used successfully.8.1.2 Completely dissolve 10 g of TCEP in 100 mL of methylene chloride. Next add 40 g of 80/100 mesh Chromosorb P(AW)to the TCEP solution. Quickly transfer this mixture to a drying dish, i
