ASTM D5580-02(2007)
(Test Method)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 Chromatography
Standard Test Method for Determination of Benzene, Toluene, Ethylbenzene, <span class="italic"> p/m</span>-Xylene, <span class="italic">o</span>-Xylene, C<sub>9</sub> and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography
SIGNIFICANCE AND USE
Regulations limiting the concentration of benzene and the total aromatic content of finished gasoline have been established for 1995 and beyond in order to reduce the ozone reactivity and toxicity of automotive evaporative and exhaust emissions. Test methods to determine benzene and the aromatic content of gasoline are necessary to assess product quality and to meet new fuel regulations.
This test method can be used for gasolines that contain oxygenates (alcohols and ethers) as additives. It has been determined that the common oxygenates found in finished gasoline do not interfere with the analysis of benzene and other aromatics by this test method.
SCOPE
1.1 This test method covers the determination of benzene, toluene, ethylbenzene, the xylenes, C9 and heavier aromatics, and total aromatics in finished motor gasoline by gas chromatography.
1.2 The aromatic hydrocarbons are separated without interferences from other hydrocarbons in finished gasoline. Nonaromatic hydrocarbons having a boiling point greater than n-dodecane may cause interferences with the determination of the C9 and heavier aromatics. For the C8 aromatics, p-xylene and m-xylene co-elute while ethylbenzene and o-xylene are separated. The C9 and heavier aromatics are determined as a single group.
1.3 This test method covers the following concentration ranges, in liquid volume %, for the preceding aromatics: benzene, 0.1 to 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 reported 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 increase octane, do not interfere with the analysis. Ethers such as methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmethylether (TAME), and diisopropylether (DIPE) have been found to elute from the precolumn with the nonaromatic hydrocarbons 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 precolumn to vent and does not interfere with benzene.
1.6 The values stated in SI units are to be regarded as the standard. The values given 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 responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5580 − 02(Reapproved 2007)
Standard Test Method for
Determination of Benzene, Toluene, Ethylbenzene, p/m-
Xylene, o-Xylene, C and Heavier Aromatics, and Total
Aromatics in Finished Gasoline by Gas Chromatography
This standard is issued under the fixed designation D5580; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.6 The values stated in SI units are to be regarded as
standard. The values given in parentheses are for information
1.1 This test method covers the determination of benzene,
only.
toluene, ethylbenzene, the xylenes, C and heavier aromatics,
and total aromatics in finished motor gasoline by gas chroma- 1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
tography.
responsibility of the user of this standard to establish appro-
1.2 The aromatic hydrocarbons are separated without inter-
priate safety and health practices and determine the applica-
ferences from other hydrocarbons in finished gasoline. Non-
bility of regulatory limitations prior to use.
aromatic hydrocarbons having a boiling point greater than
n-dodecane may cause interferences with the determination of
2. Referenced Documents
the C and heavier aromatics. For the C aromatics, p-xylene
9 8
and m-xylene co-elute while ethylbenzene and o-xylene are 2.1 ASTM Standards:
separated. The C and heavier aromatics are determined as a
D1298 Test Method for Density, Relative Density (Specific
single group. Gravity), or API Gravity of Crude Petroleum and Liquid
Petroleum Products by Hydrometer Method
1.3 This test method covers the following concentration
D4052 Test Method for Density, Relative Density, and API
ranges, in liquid volume %, for the preceding aromatics:
Gravity of Liquids by Digital Density Meter
benzene, 0.1 to 5 %; toluene, 1 to 15 %; individual C
D4057 Practice for Manual Sampling of Petroleum and
aromatics, 0.5 to 10 %; total C and heavier aromatics, 5 to
Petroleum Products
30 %, and total aromatics, 10 to 80 %.
D4307 Practice for Preparation of Liquid Blends for Use as
1.4 Resultsarereportedtothenearest0.01 %byeithermass
Analytical Standards
or by liquid volume.
E355 Practice for Gas Chromatography Terms and Relation-
1.5 Many of the common alcohols and ethers that are added ships
to gasoline to reduce carbon monoxide emissions and increase
octane,donotinterferewiththeanalysis.Etherssuchasmethyl
3. Terminology
tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-
3.1 Definitions of Terms Specific to This Standard:
amylmethylether (TAME), and diisopropylether (DIPE) have
3.1.1 aromatic—any organic compound containing a ben-
been found to elute from the precolumn with the nonaromatic
zene ring.
hydrocarbons to vent. Other oxygenates, including methanol
3.1.2 low-volume connector—aspecialunionforconnecting
and ethanol elute before benzene and the aromatic hydrocar-
two lengths of narrow bore tubing 1.6-mm (0.06-in.) outside
bons. 1-Methylcyclopentene has also been found to elute from
diameterandsmaller;sometimesthisisreferredtoaszerodead
the precolumn to vent and does not interfere with benzene.
volume union.
3.1.3 narrow bore tubing—tubing used to transfer compo-
nents prior to or after separation; usually 0.5-mm (0.02-in.)
inside diameter and smaller.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2007. Published January 2008. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1994. Last previous edition approved in 2002 as D5580–02. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D5580-02R07. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5580 − 02 (2007)
FIG. 1 Valve Diagram, Aromatics in Gasoline
3.1.4 split ratio—in capillary gas chromatography, the ratio o-xylene has eluted, the flow through the nonpolar WCOT
of the total flow of carrier gas to the sample inlet versus the columnisreversedtobackflushtheC andheavieraromaticsto
flow of the carrier gas to the capillary column, expressed by: the flame ionization detector.
split ratio 5 S1C /C (1) 4.3 From the first analysis, the peak areas of benzene,
~ !
toluene, and the internal standard (2-hexanone) are measured
where:
and recorded. Peak areas for ethylbenzene, p/m-xylene,
S = flow rate at the splitter vent and
o-xylene, the C and heavier aromatics, and internal standard
C = flow rate at the column outlet.
are measured and recorded from the second analysis. The
3.1.5 1,2,3-tris-2-cyanoethoxypropane (TCEP)—a polar gas
backflush peak eluting from the WCOT column in the second
chromatographic liquid phase.
analysis contains only C and heavier aromatics.
3.1.6 wall-coated open tubular (WCOT)—a type of capil-
4.4 The flame ionization detector response, proportional to
larycolumnpreparedbycoatingtheinsidewallofthecapillary
the concentration of each component, is used to calculate the
with a thin film of stationary phase.
amount of aromatics that are present with reference to the
internal standard.
4. Summary of Test Method
5. Significance and Use
4.1 Atwo-column chromatographic system equipped with a
columnswitchingvalveandaflameionizationdetectorisused.
5.1 Regulations limiting the concentration of benzene and
A reproducible volume of sample containing an appropriate the total aromatic content of finished gasoline have been
internal standard such as 2-hexanone is injected onto a precol-
established for 1995 and beyond in order to reduce the ozone
umn containing a polar liquid phase (TCEP). The C and reactivity and toxicity of automotive evaporative and exhaust
lighter nonaromatics are vented to the atmosphere as they elute
emissions.Testmethodstodeterminebenzeneandthearomatic
from the precolumn. A thermal conductivity detector may be content of gasoline are necessary to assess product quality and
used to monitor this separation. The TCEP precolumn is
to meet new fuel regulations.
backflushedimmediatelybeforetheelutionofbenzene,andthe
5.2 This test method can be used for gasolines that contain
remaining portion of the sample is directed onto a second
oxygenates (alcohols and ethers) as additives. It has been
column containing a nonpolar liquid phase (WCOT). Benzene,
determined that the common oxygenates found in finished
toluene, and the internal standard elute in the order of their
gasolinedonotinterferewiththeanalysisofbenzeneandother
boiling points and are detected by a flame ionization detector.
aromatics by this test method.
Immediately after the elution of the internal standard, the flow
through the nonpolar WCOT column is reversed to backflush 6. Apparatus
theremainderofthesample(C andheavieraromaticsplusC
8 10
6.1 Chromatographic System—See Practice E355 for spe-
and heavier nonaromatics) from the column to the flame
cific designations and definitions. Refer to Fig. 1 for a diagram
ionization detector.
of the system.
4.2 The analysis is repeated a second time allowing the C 6.1.1 Gas Chromatograph (GC), capable of operating at the
and lighter nonaromatics, benzene and toluene to elute from conditions given in Table 1, and having a column switching
the polar TCEP precolumn to vent. A thermal conductivity and backflushing system equivalent to Fig. 1. Carrier gas
detector may be used to monitor this separation. The TCEP pressure and flow control devices shall be capable of precise
precolumn is backflushed immediately prior to the elution of control when column head pressures and flow rates are low.
ethylbenzene and the remaining aromatic portion is directed 6.1.2 Sample Introduction System, capable of introducing a
into theWCOTcolumn.The internal standard and C aromatic representative sample into the gas chromatographic inlet.
components elute in the order of their boiling points and are Microlitre syringes and automatic syringe injectors have been
detected by a flame ionization detector. Immediately after used successfully.
D5580 − 02 (2007)
TABLE 1 Typical Chromatographic Operating Parameters 130
6.1.5.3 An automatic valve switching device is strongly
Temperatures recommended to ensure repeatable switching times.
Injection port (split injector) 200°C
6.2 Data Acquisition System:
FID (Detector A) 250°C
6.2.1 Integrator or Computer, capable of providing real-
TCD (Detector B) 200°C
Nonpolar WCOT capillary
time graphic and digital presentation of the chromatographic
Initial 60°C (6 min)
data are recommended for use. Peak areas and retention times
Program rate 2°C/min
can be measured by computer or electronic integration.
Final 115°C (hold until all
components elute)
6.2.1.1 It is recommended that this device be capable of
Polar TCEP precolumn (temperature to 60°C or same as nonpolar WCOT
performing multilevel internal-standard-type calibrations and
remain constant before time to capillary if TCEP/WCOT columns
be able to calculate the correlation coefficient (r ) and linear
BACKFLUSH, T1 or T2. Do not exceed contained in identical heated zone.
maximum operating temperature.)
least square fit equation for each calibration data set in
Valve >115°C or same as nonpolar WCOT
accordance with 11.4.
capillary if valve and WCOT column
contained in identical heated zone.
6.3 Chromatographic Columns (two columns are used):
Flows and Conditions
6.3.1 Polar Precolumn, to perform a pre-separation of the
Carrier gas helium
Flow to TCEP precolumn (split injector) 10 mL/min
aromatics from nonaromatic hydrocarbons in the same boiling
Flow to WCOT capillary (auxiliary flow) 10 mL/min
point range. Any column with equivalent or better chromato-
Flow from split vent 100 mL/min
graphic efficiency and selectivity in accordance with 6.3.1.1
Detector gases as necessary
Split ratio 11:1
can be used.
Sample size 1 µL
6.3.1.1 TCEP Micro-Packed Column, 560-mm (22-in.) by
1.6-mm ( ⁄16-in.) outside diameter by 0.76-mm (0.030-in.)
inside diameter stainless steel tube packed with 0.14 to 0.15 g
6.1.3 Inlet System, (splitting type)—Split injection is neces- of 20 % (mass/mass) TCEP on 80/100 mesh Chromosorb
sary to maintain the actual chromatographed sample size P(AW). This column was used in the cooperative study to
within the limits required for optimum column efficiency and provide the precision and bias data referred to in Section 15.
detector linearity.
6.3.2 Nonpolar (Analytical) Column—Any column with
6.1.3.1 Some gas chromatographs are equipped with on- equivalent or better chromatographic efficiency and selectivity
column injectors and autosamplers which can inject submi-
in accordance with 6.3.2.1 can be used.
crolitre sample sizes. Such systems can be used provided that 6.3.2.1 WCOT Methyl Silicone Column, 30 m long by
column efficiency and detector linearity are comparable to
0.53-mm inside diameter fused silica WCOT column with a
systems with split injection. 5.0-µm film thickness of cross-linked methyl siloxane.
6.1.4 Detector—A flame ionization detector (Detector A) is
employed for quantitation of components eluting from the
7. Reagents and Materials
WCOT column. The flame ionization detector used for Detec-
7.1 Carrier Gas, appropriate to the type of detector used.
torAshallhavesufficientsensitivityandstabilitytodetect0.01
Helium has been used successfully.The minimum purity of the
volume % of an aromatic compound.
carrier gas used must be 99.95 mol %. Additional purification
6.1.4.1 It is strongly recommended that a thermal conduc-
may be necessary to remove trace amounts of oxygen.
tivity detector be placed on the vent of the TCEP precolumn
(Warning—Helium is usually supplied as a compressed gas
(Detector B). This facilitates the determination of valve
under high pressure.)
BACKFLUSH and RESET times (10.5) and is useful for
7.2 Methylene Chloride—Used for column preparation. Re-
monitoring the separation of the polar TCEP precolumn.
agent grade, free of nonvolatile residue. (Warning—Harmful
6.1.5 SwitchingandBackflushingValve,tobelocatedwithin
when ingested or inhaled at high concentrations.)
a temperature-controlled heated zone and capable of perform-
ing the functions in accordance with Section 10, and illustrated
7.3 2,2,4-Trimethylpentane (isooctane)—Used as a solvent
in Fig. 1. The valve shall be of low internalvolume design and
in the preparation of the calibration mixture. Reagent grade.
notcontributesignificantlytodeteriorationofchromatographic
(Warning—Isooctaneisflammableandcanbeharmfulorfatal
resolution.
when ingested or inhaled.
6.1.5.1 A 10-port valve with 1.6-mm (0.06) outside diam-
7.4 Standards for Calibration and Identification, required
eter fittings is recommended for this test method. Alternately,
for all components to be analyzed and the internal standard.
and if using columns of 0.32-mm inside diameter or smaller, a
Standards are used for establishing identification by retention
valve with 0.8-mm (0.03-in.) outside diameter fittings should
time as well as calibration for quantitative measurements.
be used.
These materials shall be of known purity and free of the other
6.1.5.2 Some gas chromatographs are equipped with an
components to be analyzed. (Warning—These materials are
auxiliary oven which can be used to contain the valve. In such
flammable and may be harmful or fatal when ingested or
a configuration, the valve can be kept at a higher temperature
inhaled.
than the polar and nonpolar columns to prevent sample
condensation and peak broadening. The columns are then
8. Preparation of Columns
located in the main oven and the temperature can be adjusted
for optimum aromatic resolution. 8.1 TCEP Column Packing:
D5580 − 02 (2007)
8.1.1 Use any satisfactory method, that will produce a film thickness, or both, are used, it may be necessary to use
column capable of retaining aromatics from nonaromatic different optimum flows and temperatures.
components of the same boiling point range in a gasoline
10.2.2 Conditions listed in Table 1 are applicable to the
sample. The following procedure has been used successfully.
columnsdescribedin6.3.IfaWCOTcolumnofadifferentfilm
8.1.2 Completely dissolve 10 g of TCEP in 100 mL of
thickness is used, the conditions chosen for the analysis must
methylene chloride.
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
An American National Standard
Designation:D5580–00 Designation: D 5580 – 02 (Reapproved 2007)
Standard Test Method for
Determination of Benzene, Toluene, Ethylbenzene, p/m-
Xylene, o-Xylene, C and Heavier Aromatics, and Total
Aromatics in Finished Gasoline by Gas Chromatography
This standard is issued under the fixed designation D 5580; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of benzene, toluene, ethylbenzene, the xylenes, C and heavier aromatics, and
total aromatics in finished motor gasoline by gas chromatography.
1.2 The aromatic hydrocarbons are separated without interferences from other hydrocarbons in finished gasoline. Nonaromatic
hydrocarbons having a boiling point greater than n-dodecane may cause interferences with the determination of the C and heavier
aromatics. For the C aromatics, p-xylene and m-xylene co-elute while ethylbenzene and o-xylene are separated. The C and
8 9
heavier aromatics are determined as a single group.
1.3 This test method covers the following concentration ranges, in liquid volume %, for the preceding aromatics: benzene, 0.1
to 5 %; toluene, 1 to 15 %; individual C aromatics, 0.5 to 10 %; total C and heavier aromatics, 5 to 30 %, and total aromatics,
8 9
10 to 80 %.
1.4 Results are reported 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 increase
octane, do not interfere with the analysis. Ethers such as methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE),
tert-amylmethylether (TAME), and diisopropylether (DIPE) have been found to elute from the precolumn with the nonaromatic
hydrocarbons 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 precolumn to vent and does not interfere with benzene.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.04.0L
on Gas Chromatography Methods.
Current edition approved Apr. 10, 2000.Nov. 1, 2007. Published June 2000.January 2008. Originally published as D5580–94.approved in 1994. Last previous edition
D5580–95.approved in 2002 as D 5580–02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5580 – 02 (2007)
1.6 ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareprovidedforinformation
only; they may not be exact equivalents. only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D 1298Practice Test Method for Density, Relative Density,Density (Specific Gravity), orAPI Gravity of Crude Petroleum and
Liquid Petroleum Products by Hydrometer Method
D 4052 Test Method for Density and Relative Density of Liquids by Digital Density Meter
D 4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D 4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
E 355 Practice for Gas Chromatography Terms and Relationships
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 aromatic—any organic compound containing a benzene ring.
3.1.2 low-volume connector—a special union for connecting two lengths of narrow bore tubing 1.6-mm (0.06-in.) outside
diameter and smaller; sometimes this is referred to as zero dead volume union.
3.1.3 narrow bore tubing—tubing used to transfer components prior to or after separation; usually 0.5-mm (0.02-in.) inside
diameter and smaller.
3.1.4 split ratio—in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flow
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 and
C = 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 with
a thin film of stationary phase.
4. Summary of Test Method
4.1 Atwo-column chromatographic system equipped with a column switching valve and a flame ionization detector is used.A
reproducible volume of sample containing an appropriate internal standard such as 2-hexanone is injected onto a precolumn
containing a polar liquid phase (TCEP). The C and lighter nonaromatics are vented to the atmosphere as they elute from the
precolumn. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn is backflushed
immediately before the elution of benzene, and the remaining portion of the sample is directed onto a second column containing
a nonpolar liquid phase (WCOT). Benzene, toluene, and the internal standard elute in the order of their boiling points and are
detectedbyaflameionizationdetector.Immediatelyaftertheelutionoftheinternalstandard,theflowthroughthenonpolarWCOT
column is reversed to backflush the remainder of the sample (C and heavier aromatics plus C and heavier nonaromatics) from
8 10
the column to the flame ionization detector.
4.2 The analysis is repeated a second time allowing the C and lighter nonaromatics, benzene and toluene to elute from the
polar TCEP precolumn to vent. A thermal conductivity detector may be used to monitor this separation. The TCEP precolumn is
backflushed immediately prior to the elution of ethylbenzene and the remaining aromatic portion is directed into the WCOT
column. The internal standard and C aromatic components elute in the order of their boiling points and are detected by a flame
ionization detector. Immediately after o-xylene has eluted, the flow through the nonpolar WCOT column is reversed to backflush
the C and heavier aromatics to the flame ionization detector.
4.3 From the first analysis, the peak areas of benzene, toluene, and the internal standard (2-hexanone) are measured and
recorded. Peak areas for ethylbenzene, p/m-xylene, o-xylene, the C and heavier aromatics, and internal standard are measured and
recorded from the second analysis. The backflush peak eluting from the WCOT column in the second analysis contains only C
and heavier aromatics.
4.4 Theflameionizationdetectorresponse,proportionaltotheconcentrationofeachcomponent,isusedtocalculatetheamount
of aromatics that are present with reference to the internal standard.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
, Vol 05.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
D 5580 – 02 (2007)
5. Significance and Use
5.1 Regulations limiting the concentration of benzene and the total aromatic content of finished gasoline have been established
for 1995 and beyond in order to reduce the ozone reactivity and toxicity of automotive evaporative and exhaust emissions. Test
methods to determine benzene and the aromatic content of gasoline are necessary to assess product quality and to meet new fuel
regulations.
5.2 Thistestmethodcanbeusedforgasolinesthatcontainoxygenates(alcoholsandethers)asadditives.Ithasbeendetermined
that the common oxygenates found in finished gasoline do not interfere with the analysis of benzene and other aromatics by this
test method.
6. Apparatus
6.1 Chromatographic System—See Practice E 355 for specific designations and definitions. Refer to Fig. 1 for a diagram of the
system.
6.1.1 Gas Chromatograph (GC), capable of operating at the conditions given in Table 1, and having a column switching and
backflushing system equivalent to Fig. 1. Carrier gas pressure and flow control devices shall be capable of precise control when
column head pressures and flow rates are low.
6.1.2 Sample Introduction System,capableofintroducingarepresentativesampleintothegaschromatographicinlet.Microlitre
syringes and automatic syringe injectors have been used successfully.
6.1.3 Inlet System, (splitting type)— Split injection is necessary to maintain the actual chromatographed sample size within the
limits 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 submicrolitre
sample sizes. Such systems can be used provided that column efficiency and detector linearity are comparable to systems with split
injection.
6.1.4 Detector—Aflame ionization detector (DetectorA) is employed for quantitation of components eluting from the WCOT
column. The flame ionization detector used 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 theTCEPprecolumn (Detector
B). This facilitates the determination of valve BACKFLUSH and RESET times (10.5) and is useful for monitoring the separation
of the polar TCEP precolumn.
6.1.5 Switching and Backflushing Valve, to be located within a temperature-controlled heated zone and capable of performing
the functions in accordance with Section 10, and illustrated in Fig. 1. The valve shall be of low internalvolume design and not
contribute 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 if
using columns of 0.32-mm inside diameter or smaller, a valve with 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 a
configuration, the valve can be kept at a higher temperature than the polar and nonpolar columns to prevent sample condensation
and peak broadening. The columns are then located in the main oven and the temperature can be adjusted for optimum aromatic
resolution.
6.1.5.3 An automatic valve switching device is strongly recommended 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 chromatographic data are
recommended 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 capable of performing multilevel internal-standard-type calibrations and be able
to calculate the correlation coefficient (r ) and linear least square fit equation for each calibration data set in accordance with 11.4.
FIG. 1 Valve Diagram, Aromatics in Gasoline
D 5580 – 02 (2007)
TABLE 1 Typical Chromatographic Operating Parameters 130
Temperatures
Injection port (split injector) 200°C
FID (Detector A) 250°C
TCD (Detector B) 200°C
Nonpolar WCOT capillary
Initial 60°C (6 min)
Program rate 2°C/min
Final 115°C (hold until all
components elute)
Polar TCEP precolumn (temperature to 60°C or same as nonpolar WCOT
remain constant before time to capillary if TCEP/WCOT columns
BACKFLUSH, T1 or T2. Do not exceed contained in identical heated zone.
maximum operating temperature.)
Valve >115°C or same as nonpolar WCOT
capillary if valve and WCOT column
contained in identical heated zone.
Flows and Conditions
Carrier gas helium
Flow to TCEP precolumn (split injector) 10 mL/min
Flow to WCOT capillary (auxiliary flow) 10 mL/min
Flow from split vent 100 mL/min
Detector gases as necessary
Split ratio 11:1
Sample size 1 µL
6.3 Chromatographic Columns (two columns are used):
6.3.1 Polar Precolumn, to perform a pre-separation of the aromatics from nonaromatic hydrocarbons in the same boiling point
range. 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 ( ⁄16-in.) outside diameter by 0.76-mm (0.030-in.) inside
diameter stainless steel tube packed with 0.14 to 0.15 g of 20 % (mass/mass) TCEP on 80/100 mesh Chromosorb P(AW). This
column was used in the cooperative study to provide the precision and bias data referred to in Section 15.
6.3.2 Nonpolar (Analytical) Column—Any column with equivalent or better chromatographic efficiency and selectivity in
accordance 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 silicaWCOTcolumn with a 5.0-µm film
thickness of cross-linked methyl siloxane.
7. Reagents and Materials
7.1 Carrier Gas, appropriate to the type of detector used. Helium has been used successfully.The minimum purity of the carrier
gas used must be 99.95 mol %.Additional purification may be necessary to remove trace amounts of oxygen. (Warning—Helium
is usually supplied as a compressed gas under high pressure.)
7.2 Methylene Chloride—Used for column preparation. Reagent grade, free of nonvolatile residue. (Warning—Harmful when
ingested 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.
(Warning—Isooctane is flammable and can be harmful or fatal when ingested or inhaled.
7.4 Standards for Calibration and Identification,requiredforallcomponentstobeanalyzedandtheinternalstandard.Standards
are used for establishing identification by retention time as well as calibration for quantitative measurements.These materials shall
be of known purity and free of the other components to be analyzed. (Warning—These materials are flammable and may be
harmful or fatal when ingested or inhaled.
8. Preparation of Columns
8.1 TCEP Column Packing:
8.1.1 Use any satisfactory method, that will produce a column capable of retaining aromatics from nonaromatic components of
the same boiling point range i
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