ASTM D5580-15(2020)
(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, <emph type="ital"> p/m</emph>-Xylene, <emph type="ital">o</emph>-Xylene, C<inf>9</inf> and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography
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 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 This test method includes a relative bias section for U.S. EPA spark-ignition engine fuel regulations reporting for benzene based on Practice D6708 accuracy assessment between Test Method D5580 and Test Method D3606 as a possible Test Method D5580 alternative to Test Method D3606. The Practice D6708 derived correlation equation is only applicable for fuels in the benzene concentration range from 0.0 % to 2.31 % by volume as measured by Test Method D5580. The applicable Test Method D3606 range for benzene is from 0.0 % to 2.38 % by volume as reported by Test Method D3606.
1.6 This test method includes a relative bias section for U.S. EPA spark-ignition engine fuel regulations for total aromatics reporting based on Practice D6708 accuracy assessment between Test Method D5580 and Test Method D5769 as a possible Test Method D5580 alternative to Test Method D5769. The Practice D6708 derived correlation equation(s) is only applicable for fuels in the total aromatic concentration range from 5.4 % to 31.6 % by volume as measured by Test Method D5580 and a distillation temperature T95, at which 95 % of the sample has evaporated, as measured by Test Method D86 is in the range of 149.1 °C to 196.6 °C (300.4 °F to 385.9 °F).
1.6.1 The applicable Test Method D5769 range for total aromatics is from 3.7 % to 29.4 % by volume as reported by Test Method D5769 and the distillation temperature T95, at which 95 % of the sample has evaporated, when tested according to Test Method D86 ranged from 149.1 °C to 196.6 °C (300.4 °F to 385.9 °F).
1.7 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.
1.8 The values stated in SI units are to be regarded as standard.
1.8.1 Exception—The values given in parentheses are for informat...
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Designation: D5580 − 15 (Reapproved 2020)
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 tween Test Method D5580 and Test Method D5769 as a
possible Test Method D5580 alternative to Test Method
1.1 This test method covers the determination of benzene,
D5769. The Practice D6708 derived correlation equation(s) is
toluene, ethylbenzene, the xylenes, C and heavier aromatics,
only applicable for fuels in the total aromatic concentration
and total aromatics in finished motor gasoline by gas chroma-
range from 5.4 % to 31.6 % by volume as measured by Test
tography.
Method D5580 and a distillation temperature T , at which
1.2 The aromatic hydrocarbons are separated without inter-
95 % of the sample has evaporated, as measured by Test
ferences from other hydrocarbons in finished gasoline. Non-
Method D86 is in the range of 149.1 °C to 196.6 °C (300.4 °F
aromatic hydrocarbons having a boiling point greater than
to 385.9 °F).
n-dodecane may cause interferences with the determination of
1.6.1 The applicable Test Method D5769 range for total
the C and heavier aromatics. For the C aromatics, p-xylene
9 8
aromatics is from 3.7 % to 29.4 % by volume as reported by
and m-xylene co-elute while ethylbenzene and o-xylene are
Test Method D5769 and the distillation temperature T ,at
separated. The C and heavier aromatics are determined as a
which 95 % of the sample has evaporated, when tested
single group.
according to Test Method D86 ranged from 149.1 °C to
1.3 This test method covers the following concentration
196.6 °C (300.4 °F to 385.9 °F).
ranges, in liquid volume %, for the preceding aromatics:
1.7 Many of the common alcohols and ethers that are added
benzene, 0.1 % to 5 %; toluene, 1 % to 15 %; individual C
to gasoline to reduce carbon monoxide emissions and increase
aromatics, 0.5 % to 10 %; total C and heavier aromatics, 5 %
octane,donotinterferewiththeanalysis.Etherssuchasmethyl
to 30 %, and total aromatics, 10 % to 80 %.
tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-
1.4 Resultsarereportedtothenearest0.01 %byeithermass
amylmethylether (TAME), and diisopropylether (DIPE) have
or by liquid volume.
been found to elute from the precolumn with the nonaromatic
hydrocarbons to vent. Other oxygenates, including methanol
1.5 This test method includes a relative bias section for U.S.
and ethanol elute before benzene and the aromatic hydrocar-
EPA spark-ignition engine fuel regulations reporting for ben-
bons. 1-Methylcyclopentene has also been found to elute from
zene based on Practice D6708 accuracy assessment between
the precolumn to vent and does not interfere with benzene.
Test Method D5580 and Test Method D3606 as a possible Test
MethodD5580alternativetoTestMethodD3606.ThePractice
1.8 The values stated in SI units are to be regarded as
D6708 derived correlation equation is only applicable for fuels
standard.
in the benzene concentration range from 0.0 % to 2.31 % by
1.8.1 Exception—The values given in parentheses are for
volume as measured by Test Method D5580. The applicable
information only.
Test Method D3606 range for benzene is from 0.0 % to 2.38 %
1.9 This standard does not purport to address all of the
by volume as reported by Test Method D3606.
safety concerns, if any, associated with its use. It is the
1.6 This test method includes a relative bias section for U.S.
responsibility of the user of this standard to establish appro-
EPA spark-ignition engine fuel regulations for total aromatics
priate safety, health, and environmental practices and deter-
reporting based on Practice D6708 accuracy assessment be-
mine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
ization established in the Decision on Principles for the
Subcommittee D02.04.0L on Gas Chromatography Methods.
Development of International Standards, Guides and Recom-
CurrenteditionapprovedJune1,2020.PublishedJuly2020.Originallyapproved
mendations issued by the World Trade Organization Technical
in 1994. Last previous edition approved in 2015 as D5580 – 15. DOI: 10.1520/
D5580-15R20. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5580 − 15 (2020)
2. Referenced Documents A reproducible volume of sample containing an appropriate
2 internal standard such as 2-hexanone is injected onto a precol-
2.1 ASTM Standards:
umn containing a polar liquid phase (TCEP). The C and
D86 Test Method for Distillation of Petroleum Products and
lighter nonaromatics are vented to the atmosphere as they elute
Liquid Fuels at Atmospheric Pressure
from the precolumn. A thermal conductivity detector may be
D1298 Test Method for Density, Relative Density, or API
used to monitor this separation. The TCEP precolumn is
Gravity of Crude Petroleum and Liquid Petroleum Prod-
backflushedimmediatelybeforetheelutionofbenzene,andthe
ucts by Hydrometer Method
remaining portion of the sample is directed onto a second
D3606 Test Method for Determination of Benzene and
column containing a nonpolar liquid phase (WCOT). Benzene,
Toluene in Spark Ignition Fuels by Gas Chromatography
toluene, and the internal standard elute in the order of their
D4052 Test Method for Density, Relative Density, and API
boiling points and are detected by a flame ionization detector.
Gravity of Liquids by Digital Density Meter
Immediately after the elution of the internal standard, the flow
D4057 Practice for Manual Sampling of Petroleum and
through the nonpolar WCOT column is reversed to backflush
Petroleum Products
theremainderofthesample(C andheavieraromaticsplusC
8 10
D4307 Practice for Preparation of Liquid Blends for Use as
and heavier nonaromatics) from the column to the flame
Analytical Standards
ionization detector.
D5769 Test Method for Determination of Benzene, Toluene,
4.2 The analysis is repeated a second time allowing the C
and Total Aromatics in Finished Gasolines by Gas
Chromatography/Mass Spectrometry and lighter nonaromatics, benzene and toluene to elute from
the polar TCEP precolumn to vent. A thermal conductivity
D6708 Practice for StatisticalAssessment and Improvement
of Expected Agreement Between Two Test Methods that detector may be used to monitor this separation. The TCEP
precolumn is backflushed immediately prior to the elution of
Purport to Measure the Same Property of a Material
E355 Practice for Gas Chromatography Terms and Relation- ethylbenzene and the remaining aromatic portion is directed
into theWCOTcolumn.The internal standard and C aromatic
ships
components elute in the order of their boiling points and are
3. Terminology
detected by a flame ionization detector. Immediately after
3.1 Definitions of Terms Specific to This Standard:
o-xylene has eluted, the flow through the nonpolar WCOT
3.1.1 aromatic, n—any organic compound containing a columnisreversedtobackflushtheC andheavieraromaticsto
benzene ring.
the flame ionization detector.
3.1.2 low-volume connector, n—a special union for connect-
4.3 From the first analysis, the peak areas of benzene,
ing two lengths of narrow bore tubing 1.6 mm (0.06 in.)
toluene, and the internal standard (2-hexanone) are measured
outside diameter and smaller; sometimes this is referred to as
and recorded. Peak areas for ethylbenzene, p/m-xylene,
zero dead volume union.
o-xylene, the C and heavier aromatics, and internal standard
are measured and recorded from the second analysis. The
3.1.3 narrow bore tubing, n—tubing used to transfer com-
backflush peak eluting from the WCOT column in the second
ponents prior to or after separation; usually 0.5 mm (0.02 in.)
analysis contains only C and heavier aromatics.
inside diameter and smaller.
4.4 The flame ionization detector response, proportional to
3.1.4 split ratio, n—in capillary gas chromatography, the
the concentration of each component, is used to calculate the
ratio of the total flow of carrier gas to the sample inlet versus
amount of aromatics that are present with reference to the
the flow of the carrier gas to the capillary column, expressed
internal standard.
by:
split ratio 5 ~S1C!/C (1) 5. Significance and Use
5.1 Regulations limiting the concentration of benzene and
where:
the total aromatic content of finished gasoline have been
S = flow rate at the splitter vent, and
established for 1995 and beyond in order to reduce the ozone
C = flow rate at the column outlet.
reactivity and toxicity of automotive evaporative and exhaust
3.1.5 1,2,3-tris-2-cyanoethoxypropane (TCEP), n—a polar
emissions.Testmethodstodeterminebenzeneandthearomatic
gas chromatographic liquid phase.
content of gasoline are necessary to assess product quality and
3.1.6 wall-coated open tubular (WCOT), n—a type of cap-
to meet new fuel regulations.
illary column prepared by coating the inside wall of the
5.2 This test method can be used for gasolines that contain
capillary with a thin film of stationary phase.
oxygenates (alcohols and ethers) as additives. It has been
4. Summary of Test Method determined that the common oxygenates found in finished
gasolinedonotinterferewiththeanalysisofbenzeneandother
4.1 Atwo-column chromatographic system equipped with a
aromatics by this test method.
columnswitchingvalveandaflameionizationdetectorisused.
6. Apparatus
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.1 Chromatographic System—See Practice E355 for spe-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
cific designations and definitions. Refer to Fig. 1 for a diagram
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. of the system.
D5580 − 15 (2020)
FIG. 1 Valve Diagram, Aromatics in Gasoline
TABLE 1 Typical Chromatographic Operating Parameters 130
6.1.1 Gas Chromatograph (GC), capable of operating at the
Temperatures
conditions given in Table 1, and having a column switching
and backflushing system equivalent to Fig. 1. Carrier gas Injection port (split injector) 200 °C
FID (Detector A) 250 °C
pressure and flow control devices shall be capable of precise
TCD (Detector B) 200 °C
control when column head pressures and flow rates are low.
Nonpolar WCOT capillary
Initial 60 °C (6 min)
6.1.2 Sample Introduction System, capable of introducing a
Program rate 2 °C ⁄min
representative sample into the gas chromatographic inlet.
Final 115 °C (hold until all
Microlitre syringes and automatic syringe injectors have been
components elute)
Polar TCEP precolumn (temperature to 60 °C or same as nonpolar WCOT
used successfully.
remain constant before time to capillary if TCEP/WCOT columns
6.1.3 Inlet System, (splitting type)—Split injection is neces-
BACKFLUSH, T1 or T2. Do not exceed contained in identical heated zone.
sary to maintain the actual chromatographed sample size
maximum operating temperature.)
Valve >115 °C or same as nonpolar WCOT
within the limits required for optimum column efficiency and
capillary if valve and WCOT column
detector linearity.
contained in identical heated zone.
6.1.3.1 Some gas chromatographs are equipped with on-
Flows and Conditions
Carrier gas helium
column injectors and autosamplers which can inject submi-
Flow to TCEP precolumn (split injector) 10 mL/min
crolitre sample sizes. Such systems can be used provided that
Flow to WCOT capillary (auxiliary flow) 10 mL/min
column efficiency and detector linearity are comparable to
Flow from split vent 100 mL/min
Detector gases as necessary
systems with split injection.
Split ratio 11:1
6.1.4 Detector—A flame ionization detector (Detector A) is
Sample size 1 µL
employed for quantitation of components eluting from the
WCOT column. The flame ionization detector used for Detec-
tor A shall have sufficient sensitivity and stability to detect
condensation and peak broadening. The columns are then
0.01 % by volume of an aromatic compound.
located in the main oven and the temperature can be adjusted
6.1.4.1 It is strongly recommended that a thermal conduc-
for optimum aromatic resolution.
tivity detector be placed on the vent of the TCEP precolumn
6.1.5.3 An automatic valve switching device is strongly
(Detector B). This facilitates the determination of valve
recommended to ensure repeatable switching times.
BACKFLUSH and RESET times (10.5) and is useful for
6.2 Data Acquisition System:
monitoring the separation of the polar TCEP precolumn.
6.2.1 Integrator or Computer, capable of providing real-
6.1.5 Switching and Backflushing Valve,tobelocatedwithin
time graphic and digital presentation of the chromatographic
a temperature-controlled heated zone and capable of perform-
data are recommended for use. Peak areas and retention times
ing the functions in accordance with Section 10, and illustrated
can be measured by computer or electronic integration.
in Fig. 1. The valve shall be of low internalvolume design and
6.2.1.1 It is recommended that this device be capable of
notcontributesignificantlytodeteriorationofchromatographic
performing multilevel internal-standard-type calibrations and
resolution.
be able to calculate the correlation coefficient (r ) and linear
6.1.5.1 A 10-port valve with 1.6 mm (0.06 in.) outside
least square fit equation for each calibration data set in
diameter fittings is recommended for this test method.
accordance with 11.4.
Alternatively,andifusingcolumnsof0.32 mminsidediameter
or smaller, a valve with 0.8 mm (0.03 in.) outside diameter 6.3 Chromatographic Columns (two columns are used):
fittings should be used. 6.3.1 Polar Precolumn, to perform a pre-separation of the
6.1.5.2 Some gas chromatographs are equipped with an aromatics from nonaromatic hydrocarbons in the same boiling
auxiliary oven which can be used to contain the valve. In such point range. Any column with equivalent or better chromato-
a configuration, the valve can be kept at a higher temperature graphic efficiency and selectivity in accordance with 6.3.1.1
than the polar and nonpolar columns to prevent sample can be used.
-------
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM 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.
Designation: D5580 − 15 D5580 − 15 (Reapproved 2020)
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*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,
0.10.1 % to 5 %; toluene, 11 % to 15 %; individual C aromatics, 0.50.5 % to 10 %; total C and heavier aromatics, 55 % to 30 %,
8 9
and total aromatics, 1010 % to 80 %.
1.4 Results are reported to the nearest 0.01 % by either mass or by liquid volume.
1.5 This test method includes a relative bias section for U.S. EPA spark-ignition engine fuel regulations reporting for benzene
based on Practice D6708 accuracy assessment between Test Method D5580 and Test Method D3606 as a possible Test Method
D5580 alternative to Test Method D3606. The Practice D6708 derived correlation equation is only applicable for fuels in the
benzene concentration range from 0.0 % to 2.31 % 0.0 % to 2.31 % by volume as measured by Test Method D5580. The applicable
Test Method D3606 range for benzene is from 0.0 % to 2.38 % 0.0 % to 2.38 % by volume as reported by Test Method D3606.
1.6 This test method includes a relative bias section for U.S. EPA spark-ignition engine fuel regulations for total aromatics
reporting based on Practice D6708 accuracy assessment between Test Method D5580 and Test Method D5769 as a possible Test
Method D5580 alternative to Test Method D5769. The Practice D6708 derived correlation equation(s) is only applicable for fuels
in the total aromatic concentration range from 5.4 % to 31.6 % 5.4 % to 31.6 % by volume as measured by Test Method D5580
and a distillation temperature T , at which 95 % of the sample has evaporated, as measured by Test Method D86 is in the range
of 149.1 °C to 196.6 °C (300.4 °F to 385.9 °F).
1.6.1 The applicable Test Method D5769 range for total aromatics is from 3.7 % to 29.4 % 29.4 % by volume as reported by
Test Method D5769 and the distillation temperature T , at which 95 % of the sample has evaporated, when tested according to
Test Method D86 ranged from 149.1 °C to 196.6 °C (300.4 °F to 385.9 °F).
1.7 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.
1.8 The values stated in SI units are to be regarded as standard.
1.8.1 Exception—The values given in parentheses are for information only.
1.9 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.04.0L on Gas Chromatography Methods.
Current edition approved Dec. 1, 2015June 1, 2020. Published December 2015July 2020. Originally approved in 1994. Last previous edition approved in 20132015 as
D5580 – 13.D5580 – 15. DOI: 10.1520/D5580-15.10.1520/D5580-15R20.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5580 − 15 (2020)
1.10 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D86 Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D3606 Test Method for Determination of Benzene and Toluene in Spark Ignition Fuels by Gas Chromatography
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D5769 Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasolines by Gas
Chromatography/Mass Spectrometry
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
E355 Practice for Gas Chromatography Terms and Relationships
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 aromatic—aromatic, n—any organic compound containing a benzene ring.
3.1.2 low-volume connector—connector, n—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, n—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—ratio, n—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 S1C /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)TCEP),—n—a polar gas chromatographic liquid phase.
3.1.6 wall-coated open tubular (WCOT)—(WCOT), n—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 A two-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
detected by a flame ionization detector. Immediately after the elution of the internal standard, the flow through the nonpolar WCOT
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.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D5580 − 15 (2020)
FIG. 1 Valve Diagram, Aromatics in Gasoline
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 The flame ionization detector response, proportional to the concentration of each component, is used to calculate the amount
of aromatics that are present with reference to the internal standard.
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 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.
6. Apparatus
6.1 Chromatographic System—See Practice E355 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, capable of introducing a representative sample into the gas chromatographic inlet. 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—A flame ionization detector (Detector A) 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 0.01 % by
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 (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)(0.06 in.) outside diameter fittings is recommended for this test method.
Alternatively, 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.
D5580 − 15 (2020)
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
6.1.5.2 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
...
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