ASTM D5986-96(2011)
(Test Method)Standard Test Method for Determination of Oxygenates, Benzene, Toluene, C8-C 12 Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography/Fourier Transform Infrared Spectroscopy
Standard Test Method for Determination of Oxygenates, Benzene, Toluene, C<sub>8</sub>-C<sub> 12</sub> Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography/Fourier Transform Infrared Spectroscopy
SIGNIFICANCE AND USE
Test methods to determine oxygenates, 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 quantitative determination of oxygenates: methyl-t-butylether (MTBE), di-isopropyl ether (DIPE), ethyl-t-butylether (ETBE), t-amylmethyl ether (TAME), methanol (MeOH), ethanol (EtOH), 2-propanol (2-PrOH), t-butanol (t-BuOH), 1-propanol (1-PrOH), 2-butanol (2-BuOH), i-butanol (i-BuOH), 1-butanol (1-BuOH); benzene, toluene and C8–C12 aromatics, and total aromatics in finished motor gasoline by gas chromatography/Fourier Transform infrared spectroscopy (GC/FTIR).
1.2 This test method covers the following concentration ranges: 0.1–20 volume % per component for ethers and alcohols; 0.1–2 volume % benzene; 1–15 volume % for toluene, 10–40 volume % total (C6–C12) aromatics.
1.3 The method has not been tested by ASTM for refinery individual hydrocarbon process streams, such as reformates, fluid catalytic cracking naphthas, etc., used in blending of gasolines.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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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Designation: D5986 − 96(Reapproved 2011)
Standard Test Method for
Determination of Oxygenates, Benzene, Toluene, C –C
8 12
Aromatics and Total Aromatics in Finished Gasoline by Gas
Chromatography/Fourier Transform Infrared Spectroscopy
This standard is issued under the fixed designation D5986; 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 Gravity of Crude Petroleum and Liquid Petroleum Prod-
ucts by Hydrometer Method
1.1 This test method covers the quantitative determination
D4052 Test Method for Density, Relative Density, and API
of oxygenates: methyl-t-butylether (MTBE), di-isopropyl ether
Gravity of Liquids by Digital Density Meter
(DIPE), ethyl-t-butylether (ETBE), t-amylmethyl ether
D4057 Practice for Manual Sampling of Petroleum and
(TAME), methanol (MeOH), ethanol (EtOH), 2-propanol (2-
Petroleum Products
PrOH), t-butanol (t-BuOH), 1-propanol (1-PrOH), 2-butanol
D4307 Practice for Preparation of Liquid Blends for Use as
(2-BuOH), i-butanol (i-BuOH), 1-butanol (1-BuOH); benzene,
Analytical Standards
toluene and C –C aromatics, and total aromatics in finished
8 12
motor gasoline by gas chromatography/Fourier Transform
3. Terminology
infrared spectroscopy (GC/FTIR).
3.1 Definitions of Terms Specific to This Standard:
1.2 This test method covers the following concentration
3.1.1 aromatics—refers to any organic compound contain-
ranges: 0.1–20 volume % per component for ethers and
ing a benzene or naphthalene ring.
alcohols; 0.1–2 volume % benzene; 1–15 volume % for
toluene, 10–40 volume % total (C –C ) aromatics.
3.1.2 calibrated aromatic component—in this test method,
6 12
refers to the individual aromatic components which have a
1.3 The method has not been tested by ASTM for refinery
specific calibration.
individual hydrocarbon process streams, such as reformates,
fluid catalytic cracking naphthas, etc., used in blending of
3.1.3 cool on-column injector—in gas chromatography,a
gasolines.
direct sample introduction system which is set at a temperature
at or below the boiling point of solutes or solvent on injection
1.4 The values stated in SI units are to be regarded as
and then heated at a rate equal to or greater than the column.
standard. No other units of measurement are included in this
Normally used to eliminate boiling point discrimination on
standard.
injectionortoreduceadsorption,orboth,onglasslinerswithin
1.5 This standard does not purport to address all of the
injectors. The sample is injected directly into the head of the
safety concerns, if any, associated with its use. It is the
capillary column tubing or retention gap.
responsibility of the user of this standard to establish appro-
3.1.4 Gram-Schmidt chromatogram—a nonselective sum-
priate safety and health practices and determine the applica-
mation of total intensity from a spectral scan per unit time
bility of regulatory limitations prior to use.
which resembles in profile a flame ionization detector chro-
2. Referenced Documents matogram.
2.1 ASTM Standards: 3.1.5 retention gap—in gas chromatography, refers to a
D1298 Test Method for Density, Relative Density, or API
deactivated precolumn which acts as a zone of low retention
power for reconcentrating bands in space. The polarity of the
precolumn must be similar to that of the analytical column.
This test method is under the jurisdiction of ASTM Committee D02 on
3.1.6 selective wavelength chromatogram (SWC)—in this
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.04.0L on Gas Chromatography Methods.
test method, refers to a selective chromatogram obtained by
Current edition approved May 1, 2011. Published May 2011. Originally
summing the spectral intensity in a narrow spectral wavelength
approved in 1996. Last previous edition approved in 2006 as D5986 – 96 (2006).
or frequency range as a function of elution time which is
DOI: 10.1520/D5986-96R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or unique to the compound being quantitated.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.1.7 uncalibrated aromatic component—in this test
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. method,referstoindividualaromaticsforwhichacalibrationis
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5986 − 96 (2011)
not available and whose concentrations are estimated from the
response factor of a calibrated aromatic component.
3.1.8 wall coated open tubular (WCOT)—atypeofcapillary
column prepared by coating or bonding the inside wall of the
capillary with a thin film of stationary phase.
4. Summary of Test Method
4.1 A gas chromatograph equipped with a methylsilicone
WCOT column is interfaced to a Fourier transform infrared
spectrometer.The sample is injected through a cool on-column
injector capable of injecting a small sample size without
overloading the column.
4.2 Calibration is performed using mixtures of specified
pure oxygenates and aromatic hydrocarbons on a mass basis.
FIG. 1 Light-Pipe GC/FTIR System
Volume % data is calculated from the densities of the indi-
vidual components and the density of the sample. Multipoint
6.2.3 The lower limit of 550 cm-1 is necessary for the
calibrations consisting of at least five levels and bracketing the
accurate determination of benzene. Fig. 2 gives an acceptable
concentration of the specified individual aromatics is required.
infrared spectra of benzene.
Unidentified aromatic hydrocarbons present which have not
been specifically calibrated for are quantitated using the
7. Reagents and Materials
response factor of 1,2,3,5-tetramethylbenzene and summed
7.1 Carrier Gas—Helium and hydrogen have been used
with the other calibrated aromatic components to obtain a total
successfully. The minimum purity of the carrier gas used must
aromatic concentration of the sample.
be 99.85 mole %. Additional purification using commercially
4.3 Specified quality control mixture(s) are analyzed to
available scrubbing reagents is recommended to remove trace
monitor the performance of the calibrated GC/FTIR system.
oxygen which may deteriorate the performance of the GC
WCOT column.
5. Significance and Use
7.2 Dilution Solvents—n-heptane and methylbenzene (tolu-
5.1 Test methods to determine oxygenates, benzene, and the
ene) used as a solvent in the preparation of the calibration
aromatic content of gasoline are necessary to assess product
mixture. Reagent grade. All at 99 % or greater purity. Free
quality and to meet new fuel regulations.
from detectable oxygenates and aromatics which may interfere
with the analysis.
5.2 This test method can be used for gasolines that contain
7.2.1 Toluene should be used as a solvent only for the
oxygenates (alcohols and ethers) as additives. It has been
preparation of C + components and must be free from inter-
determined that the common oxygenates found in finished
fering aromatics. (Warning—The gasoline samples and sol-
gasolinedonotinterferewiththeanalysisofbenzeneandother
vents used as reagents such as heptane and toluene are
aromatics by this test method.
6. Apparatus
6.1 Gas Chromatograph:
6.1.1 System equipped with temperature programmable gas
chromatograph suitable for cool-on-column injections. The
injector must allow the introduction of small (for example, 0.1
µL) sample sizes at the head of the WCOT column or a
retention gap. An autosampler is mandatory.
6.1.2 WCOT column containing a methylsilicone stationary
phase which elutes the aromatic hydrocarbons according to
their boiling points.Acolumn containing a relatively thick film
of stationary phase, such as 4 to 5 µm, is recommended to
prevent column sample overload.
6.2 FTIR Spectrometer:
6.2.1 This test method requires a light-pipe GC/FTIR sys-
tem (Fig. 1). No data have been acquired with matrix-isolation
or other deposition type systems.
6.2.2 The spectrometer must be equipped with a mercury-
cadmium-telluride(MCT)detectorcapableofdetectingfromat
least 4000 cm-1 to 550 cm-1. FIG. 2 Vapor Phase Spectrum of Benzene
D5986 − 96 (2011)
TABLE 2 GC/FTIR Aromatic Hydrocarbons Calibration
flammable and may be harmful or fatal if ingested or inhaled.
Components (Calibrated Aromatic Components)
Benzene is a known carcinogen. Use with proper ventilation.
Compound CAS No.
Safety glasses and gloves are required while preparing samples
Benzene 71-43-2
and standards.)
Methylbenzene 108-88-3
7.3 Internal Standard—1,2-dimethoxyethane (DME) or Ethylbenzene 100-41-4
1,3-Dimethylbenzene 108-38-3
deuterated compounds, or both, have been used successfully.A
1,4-Dimethylbenzene 106-42-3
single internal standard such as DME may be used. If other
1,2-Dimethylbenzene 95-47-6
(1-Methylethyl)-benzene 98-82-8
internal standards are used, a narrow selective wavelength
Propyl-benzene 103-65-1
range must be determined to generate a SWC which yields no
1-methyl-3-ethylbenzene 620-14-4
interference from other components in the sample.
1-methyl-4-ethylbenzene 622-96-8
1,3,5-trimethylbenzene 108-67-8
7.4 Liquid Nitrogen, supplied from low pressure dewar.
1-methyl-2-ethylbenzene 611-14-3
Required for cooling of the MCT detector. Dewar may be
1,2,4-trimethylbenzene 95-63-6
1,2,3-trimethylbenzene 526-73-8
connected through an electronic solenoid to the MCT cooling
Indan 496-11-7
reservoir for unattended operation. (Warning—Helium and
1,4-diethylbenzene 105-05-5
hydrogen are supplied under high pressure. Hydrogen can be
Butylbenzene 104-51-8
1,2-Diethylbenzene 135-01-3
explosive and requires special handling. Hydrogen monitors
1,2,4,5-Tetramethylbenzene 95-93-2
that automatically shut off supply to the GC in case of serious
1,2,3,5-Tetramethylbenzene 527-53-7
leaks are available from GC supply manufacturers.)
Naphthalene 91-20-3
2-methyl-naphthalene 91-57-6
7.5 Spectrometer Purge Gas, N dry air has not been tested,
2 1-methyl-naphthalene 90-12-0
but should be adequate.
NOTE 1—The FTIR spectrometer can be protected by installing appro-
priate filters to remove volatile oils or contaminants that may be present
meet certain regulatory specifications may require the use of
in commercial low quality nitrogen supplies.Aliquid nitrogen dewar may
specific sampling procedures. Consult appropriate regulations.
be used as a source for the nitrogen purge.
8.2 Take appropriate steps to minimize the loss of light
7.6 Standards for Calibration and Identification, all at 99 %
hydrocarbons from the gasoline sample while sampling and
or greater purity (Table 1 and Table 2). If reagents of high
duringanalyses.Uponreceiptinthelaboratorychillthesample
purity are not available, an accurate assay of the reagent must
in its original container to 0 to 5°C (32 to 40°F) before and
be performed using a properly calibrated GC or other tech-
after a sample is obtained for analysis.
niques. The concentration of the impurities which overlap the
other calibration components must be known and used to
8.3 After the sample is prepared for analysis with internal
correct the concentration of the calibration components. Be-
standard(s), chill the sample and transfer to an appropriate
cause of the error that may be introduced from impurity
autosampler vial with minimal headspace. Re-chill the remain-
corrections, the use of only high purity reagents is strongly
derofthesampleimmediatelyandprotectfromevaporationfor
recommended. Standards are used for calibration as well for
further analyses, if necessary.
establishing the identification by retention time in conjunction
with spectral match. 9. Calibration Procedure
9.1 Preparation of Calibration Standards—Prepare multi-
8. Sampling
component calibration standards using the compounds listed in
8.1 Make every effort to ensure that the sample is represen-
Table 1 and Table 2 by mass according to Practice D4307.
tative of the fuel source from which it is taken. Follow the
Prepare calibration solutions as described in 9.1 – 9.1.4 for
recommendations of Practice D4057 or its equivalent when each set. Adjust these concentrations, as necessary, to ensure
obtaining samples from bulk storage or pipelines. Sampling to
thattheconcentrationsofthecomponentsintheactualsamples
are bracketed by the calibration concentrations. Solid compo-
nents are weighed directly into the flask or vial. The specified
volumes of each calibration component are weighed into 100
TABLE 1 GC/FTIR Oxygenates Calibration Components
mL volumetric flasks or 100 mL septum capped vials. Prepare
Compound CAS
a calibration standard as follows. Cap and record the tare
Methyl-t-butyl ether (MTBE) 1634-04-4
weight of the 100 mL volumetric flask or vial to 0.1 mg.
Ethyl-t-butyl ether (ETBE) 637-92-3
Remove the cap and carefully add components to the flask or
Methyl-t-amyl ether (TAME) 994-05-8
Di-isopropyl ether (DIPE) 108-20-3
vial starting with the least volatile component. Cap the flask
Methanol 67-56-1
and record the net mass (Wi) of the aromatic component added
Ethanol 64-17-5
2-Propanol 67-63-0 to0.1mg.Repeattheadditionandweighingprocedureforeach
t-Butanol 75-65-0
component. Similarly add the internal standard and record its
1-Propanol 71-23-6
netmass(Ws)to0.1mg.Storethecappedcalibrationstandards
2-Butanol 15892-23-6
Isobutanol 78-83-1 in a refrigerator at 0 to 5°C (32 to 40°F) when not in use.
1-Butanol 71-36-3
1,2-dimethoxyethane (DME) (Internal Standard) 110-71-4 NOTE2—Mixallcalibrationsolutionsforatleast30sonaVortexmixer
after preparation or equivalent. Highly precise sample robotic sample
D5986 − 96 (2011)
preparation systems are available commercially. These systems may be TABLE 3 Relative Densities and Calibration Procedure for
Aromatic Hydrocarbons
used provided that the results for the quality control reference material
(Section 11) are met when prepared in this manner.
Relative Densities
Compound Calibration Set
60°F/60°F
9.1.1 Ethers and Alcohols:
Benzene 0.8845 Set A
9.1.1.1 Three sets of at least six calibration levels each
Methylbenzene 0.8719 Set A
(eighteen total solutions) are prepared bracketing the 0 to 20
Ethylbenzene 0.8717 Set A
volume % range. Set 1: for MTBE, DIPE, ETBE, TAME; Set 1,3-Dimethylbenzene 0.8687 Set A
1,4-Dimethylbenzene 0.8657 Set A
2: MeOH, EtOH, 2-PrOH, t-BuOH; and Set 3: 1-PrOH,
1,2-Dimethylbenzene 0.8848 Set A
2-BuOH, i-BuOH, 1-BuOH.
(1-Methylethyl)-benzene 0.8663 Set B
Propyl-benzene 0.8666 Set B
9.1.1.2 For each above Set
...
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