ASTM D5292-99
(Test Method)Standard Test Method for Aromatic Carbon Contents of Hydrocarbon Oils by High Resolution Nuclear Magnetic Resonance Spectroscopy
Standard Test Method for Aromatic Carbon Contents of Hydrocarbon Oils by High Resolution Nuclear Magnetic Resonance Spectroscopy
SCOPE
1.1 This test method covers the determination of the aromatic hydrogen content (Procedures A and B) and aromatic carbon content (Procedure C) of hydrocarbon oils using high-resolution nuclear magnetic resonance (NMR) spectrometers. Applicable samples include kerosenes, gas oils, mineral oils, lubricating oils, coal liquids, and other distillates that are completely soluble in chloroform and carbon tetrachloride at ambient temperature. For pulse Fourier transform (FT) spectrometers, the detection limit is typically 0.1 mol % aromatic hydrogen atoms and 0.5 mol % aromatic carbon atoms. For continuous wave (CW) spectrometers, which are suitable for measuring aromatic hydrogen contents only, the detection limit is considerably higher and typically 0.5 mol % aromatic hydrogen atoms.
1.2 The reported units are mole percent aromatic hydrogen atoms and mole percent aromatic carbon atoms.
1.3 This test method is not applicable to samples containing more than 1 mass % olefinic or phenolic compounds.
1.4 This test method does not cover the determination of the percentage mass of aromatic compounds in oils since NMR signals from both saturated hydrocarbons and aliphatic substituents on aromatic ring compounds appear in the same chemical shift region. For the determination of mass or volume percent aromatics in hydrocarbon oils, chromatographic, or mass spectrometry methods can be used.
1.5 The values stated in SI units are to be regarded as the standard.
1.6 This standard does not purport to address all of the safety problems, 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. Specific precautionary statements are given in Notes 1, 2 and 3.
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An American National Standard
Designation:D5292–99
Standard Test Method for
Aromatic Carbon Contents of Hydrocarbon Oils by High
Resolution Nuclear Magnetic Resonance Spectroscopy
This standard is issued under the fixed designation D5292; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D3238 Test Method for Calculation of Carbon Distribution
and Structural Group Analysis of Petroleum Oils by the
1.1 This test method covers the determination of the aro-
n-d-M Method
matic hydrogen content (Procedures A and B) and aromatic
D3701 Test Method for Hydrogen Content of Aviation
carbon content (Procedure C) of hydrocarbon oils using
TurbineFuelsbyLowResolutionNuclearMagneticReso-
high-resolution nuclear magnetic resonance (NMR) spectrom-
nance Spectrometry
eters. Applicable samples include kerosenes, gas oils, mineral
D4057 Practice for Manual Sampling of Petroleum and
oils, lubricating oils, coal liquids, and other distillates that are
Petroleum Products
completely soluble in chloroform at ambient temperature. For
E386 Practice for Data Presentation Relating to High-
pulse Fourier transform (FT) spectrometers, the detection limit
ResolutionNuclearMagneticResonance(NMR)Spectros-
istypically0.1mol%aromatichydrogenatomsand0.5mol%
copy
aromatic carbon atoms. For continuous wave (CW) spectrom-
2.2 Institute of Petroleum Methods:
eters, which are suitable for measuring aromatic hydrogen
IP Proposed Method BD Aromatic Hydrogen and Aromatic
contents only, the detection limit is considerably higher and
CarbonContentsofHydrocarbonOilsbyHighResolution
typically 0.5 mol % aromatic hydrogen atoms.
Nuclear Magnetic Resonance Spectroscopy
1.2 The reported units are mole percent aromatic hydrogen
atoms and mole percent aromatic carbon atoms.
3. Terminology
1.3 Thistestmethodisnotapplicabletosamplescontaining
3.1 Definitions of Terms Specific to This Standard:
more than 1 mass % olefinic or phenolic compounds.
3.1.1 aromatic carbon content—mole percent aromatic car-
1.4 Thistestmethoddoesnotcoverthedeterminationofthe
bon atoms or the percentage of aromatic carbon of the total
percentage mass of aromatic compounds in oils since NMR
carbon:
signals from both saturated hydrocarbons and aliphatic sub-
aromatic carbon content 5100
stituents on aromatic ring compounds appear in the same
3 ~aromatic carbon atoms!/~total carbon atoms! (1)
chemicalshiftregion.Forthedeterminationofmassorvolume
percent aromatics in hydrocarbon oils, chromatographic, or
3.1.1.1 Discussion—For example, the aromatic carbon con-
mass spectrometry methods can be used.
tent of toluene is 100 3(6/7) or 85.7 mol % aromatic carbon
1.5 The values stated in SI units are to be regarded as the
atoms.
standard.
3.1.2 aromatic hydrogen content—mole percent aromatic
1.6 This standard does not purport to address all of the
hydrogen atoms or the percentage of aromatic hydrogen of the
safety problems, if any, associated with its use. It is the
total hydrogen:
responsibility of the user of this standard to establish appro-
aromatic hydrogen content 5100
priate safety and health practices and determine the applica-
3 ~aromatic hydrogen atoms!/~total hydrogen atoms! (2)
bility of regulatory limitations prior to use. Specific precau-
3.1.2.1 Discussion—For example, the aromatic hydrogen
tionary statements are given in 7.2 and 7.4.
content of toluene is 100 3(5/8) or 62.5 mol % aromatic
hydrogen atoms.
2. Referenced Documents
2.1 ASTM Standards:
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
D02.04.0Fon Absorption Spectroscopic Methods. Annual Book of ASTM Standards, Vol 05.02.
Current edition approved Nov. 10, 1999. Published December 1999. Originally Annual Book of ASTM Standards, Vol 14.01.
published as D5292–92. Last previous edition D5292–93. Available from Institute of Petroleum Standards.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5292–99
3.2 Definitions of chemical shift (reported in parts per 5.3 The aromatic hydrogen and aromatic carbon contents
million (ppm)), internal reference, spectral width, and other determinedbythistestmethodcanbeusedtoevaluatechanges
NMR terminology used in this test method can be found in in aromatic contents of hydrocarbon oils due to changes in
Practice E386. processing conditions and to develop processing models in
3.3 Chloroform-d refers to chloroform solvent in which which the aromatic content of the hydrocarbon oil is a key
hydrogen is replaced by deuterium, the heavier isotope of processing indicator.
hydrogen. Chloroform-d is available from a variety of chemi-
6. Apparatus
cal and isotope suppliers.
6.1 High-Resolution Nuclear Magnetic Resonance
4. Summary of Test Method
Spectrometer—A high-resolution continuous wave (CW) or
4.1 Hydrogen ( H) nuclear magnetic resonance (NMR)
pulse Fourier transform (FT) NMR spectrometer capable of
spectra are obtained on solutions of the sample in beingoperatedaccordingtotheconditionsinTable1andTable
chloroform-d, using a CW or pulse FT high-resolution NMR
spectrometer. Carbon ( C) NMR spectra are obtained on
TABLE 1 Sample and Instrument Conditions for Continuous
solutions of the sample in chloroform-d using a pulse FT
Wave (CW) Measurements of H NMR Spectra
high-resolution NMR spectrometer. Tetramethylsilane is pre-
Solvent Chloroform-d
ferred as an internal reference in these solvents for assigning
Sample concentration Up to 50 % v/v for distillable oils
the 0.0 parts per million (ppm) chemical shift position in
Sample temperature Instrument ambient
1 13
Internal lock None
both H and C NMR spectra.
Sample spinning rate As recommended by manufacturer, typically 20 Hz
4.2 The aromatic hydrogen content of the sample is mea-
r-f Power level As recommended by instrument manufacturer
sured by comparing the integral for the aromatic hydrogen
Signal to noise level A minimum of 5:1 for the maximum height of the
smaller integrated absorption band
bandinthe HNMRspectrum(5.0to10.0ppmchemicalshift
Chemical shift reference Preferably tetramethylsilane (0.0 ppm) at no
region) with the sum of the integrals for both the aliphatic
greater than 1 vol % concentration
hydrogen band (−0.5 to 5.0 ppm region) and the aromatic
Integration Integrate over the range − 0.5 to 5.0 ppm for the
aliphatic band and 5.0 to 10.0 ppm for the aromatic
hydrogen band (5.0 to 10.0 ppm region).
band
4.3 The aromatic carbon content of the sample is measured
by comparing the integral for the aromatic carbon band in
the C spectrum (100 to 170 ppm chemical shift region) with
thesumoftheintegralsforboththealiphaticcarbonband(−10 2andofproducingpeakshavingwidthslessthanthefrequency
to 70 ppm region) and the aromatic carbon band (100 to 170 ranges of the majority of chemical shifts and coupling con-
ppm region). stants for the measured nucleus.
4.4 The integral of the aromatic hydrogen band must be 6.1.1 H NMR spectra can be obtained using either CW or
corrected for the NMR absorption line due to residual chloro- pulse FT techniques but C measurements require signal aver-
form (7.25 ppm chemical shift) in the predominantly aging and, therefore, currently require the pulse FT technique.
chloroform-d solvent.
Low resolution NMR spectrometers and procedures are not
4.5 The integrals of the aliphatic hydrogen band and of the discussed in this test method (see Test Method D3701 for an
aliphatic carbon band must be corrected for the NMR absorp-
example of the use of low resolution NMR).
tion line due to the internal chemical shift reference tetrameth- 6.2 Tube Tubes—Usuallya5or10mm outside diameter
1 13
ylsilane (0.0 ppm chemical shift in both H and C spectra). tube compatible with the configuration of the CW or pulse FT
spectrometer.
5. Significance and Use
7. Reagents and Materials
5.1 Aromatic content is a key characteristic of hydrocarbon
oilsandcanaffectavarietyofpropertiesoftheoilincludingits
7.1 Purity of Reagents—Reagent grade chemicals shall be
boiling range, viscosity, stability, and compatibility of the oil used in all tests. Unless otherwise indicated, it is intended that
with polymers.
all reagents shall conform to the specifications of the Commit-
5.2 Existing methods for estimating aromatic contents use tee onAnalytical Reagents of theAmerican Chemical Society,
physical measurements, such as refractive index, density, and
where such specifications are available. Other grades may be
numberaveragemolecularweight(seeTestMethodD3238)or used, provided it is first ascertained that the reagent is of
infrared absorbance and often depend on the availability of
sufficiently high purity to permit its use.
suitable standards. These NMR procedures do not require 7.2 Chloroform-d—For H NMR, chloroform-d must con-
standards of known aromatic hydrogen or aromatic carbon
tain less than 0.2 vol % residual chloroform. Care must be
contentsandareapplicabletoawiderangeofhydrocarbonoils taken not to contaminate the solvent with water and other
that are completely soluble in chloroform at ambient tempera-
extraneous materials. (Warning: Health hazard. Highly toxic.
ture.
“Reagent Chemicals, American Chemical Society Specification.” American
Brandes, G., “The Structural Groups of Petroleum Fractions. I. Structural Chemical Society, Washington, D.C. For suggestions on the testing of reagents not
GroupAnalysisWiththeHelpofInfraredSpectroscopy,” Brennstoff-ChemieVol37, listed by the American Chemical Society, see “Analar Standards for Laboratory
1956, p. 263. U.K.Chemicals,”BDHLtd.,Poole,Dorset,andthe“UnitedStatesPharamacopeia.”
D5292–99
TABLE 2 Sample and Instrument Conditions for Pulse Fourier
7.4 Chromium (III) 2,4-Pentanedionate, relaxation reagent
1 13
Transform Measurements of H and C NMR Spectra 13
for C NMR spectra, typically 97% grade.
Solvent:
H NMR Chloroform-d
8. Sampling
C NMR Chloroform-d
8.1 It is assumed that a representative sample acquired by a
Sample concentration:
H NMR Must be optimized for the instrument in use but
procedure of Practice D4057 or equivalent has been received
may be as high as 5 % v/v
inthelaboratory.Ifthetestisnottobeconductedimmediately
C NMR Up to 50 % v/v for petroleum distillates and 30 %
v/v for coal liquids upon receipt of the sample, store in a cool place until needed.
Relaxation agent Chromium (III) 2,4-pentanedionate recommended
8.2 A minimum of approximately 10 mL of sample is
for C NMR solutions only. Where used, a 20 mM
required for this test method. This should allow duplicate
solution (about 10 mg per mL)
Sample temperature Instrument ambient determinations, if desired.
Internal lock Deuterium (when chloroform-d is used for H
8.3 All samples must be homogeneous prior to subsam-
NMR)
pling. If any suspended particles present are attributable to
Sample spinning rate As recommended by manufacturer, typically 20 Hz
1 13
H Decoupling Only for C NMR. Broadband over the whole of
foreign matter such as rust, filter a portion of the sample to be
1 13
the H frequency range, gated on during C data
tested through a small plug of glass wool, contained in a clean
acquisition only with a decoupler rise time less
small funnel, into a clean and dry vial or NMR sample tube
than2m/s
Pulse flip angle Approximately 30°
containing chloroform-d.
Sequence delay time:
8.4 If the sample contains waxy materials, heat the sample
HNMR>10s
in the container to approximately 60°C and mix with a
CNMR>3swith and> 60 s without relaxation
agent
high-shear mixer prior to sampling. It may be necessary to
Memory size for Choose to give a minimum digitizing rate of 0.5
transfer a portion of the sample to an NMR tube containing
1 13
acquisition: Hz/point for H and 1.2 Hz/point for C NMR. If
chloroform-d by means of a pipet which has been heated to
necessary, increase memory size and zero fill
Spectral width:
approximately 60°C to maintain the homogeneity of the
H NMR At least 15 ppm in frequency and centered, as
sample.
close as possible, to the 5 ppm chemical shift
8.5 For a valid test result, samples must be completely
value
C NMR At least 250 ppm in frequency and centered, as
solubleinchloroform-d.Checktoensurethatthefinalsolution
close as possible, to the 100 ppm chemical shift
is homogeneous and free of undissolved particles.
value
Filter bandwidth Set to be equal to or greater than the spectral
9. Procedures
width and as permitted by the instrument’s filter
hardware
9.1 Three different procedures are described in this section
Exponential line Set at least equal to the digitizing rate
broadening for determining the aromatic hydrogen content, (see 9.6)
Signal to noise levels:
ProceduresAand B (see 9.7), and the aromatic carbon content
H NMR A minimum of 20:1 for the maximum height of the
of hydrocarbon oils, Procedure C (see 9.8).
smaller integrated band
C NMR A minimum of 60:1 for the maximum height of the 9.2 Theprocedureselectedbytheanalystwilldependonthe
chloroform-d resonance appearing between 75 and
available NMR instrumentation and on whether an aromatic
80 ppm on the chemical shift scale
hydrogen or aromatic carbon content is of greater value in
Chemical shift reference:
H NMR Preferably tetramethylsilane (0.0 ppm) at no
evaluating the characteristics of the hydrocarbon oil.
greater than 1 vol % concentration
9.3 Appendix X1 and Practice E386 should be used in
C NMR Preferably tetramethylsilane (0.0 ppm) at no
conjunction with the NMR spectrometer manufacturer’s in-
greater than 1 vol % concentration. If this
reference is not used, the central peak of
structionsinordertoensureoptimumperformanceoftheNMR
chloroform-d is set to 77.0 ppm
instrument in the application of these procedures.
Integration:
9.4 If tetramethylsilane is used as an internal chemical shift
H NMR Integrate over the range − 0.5 to 5.0 ppm for the
aliphatic band and 5.0 to 10.0 ppm for the aromatic standard,preparea1%v/vTMSinsolventsolutionbyadding
band
tetramethylsilane to chloroform-d solvent. Since TMS is very
C NMR Integrate over the range − 10 to 70 ppm for the
volatile, this solution should be refrigerated or replaced if the
aliphatic band and 100 to 170 ppm for the aromatic
band
characteristic absorption due to TMS is no longer evident in
1 13
theHor C NMR spectrum.
9.5 If it is inconvenient to prepare the test solution directly
in the NMR sample tube as suggested in the following
Cancer suspect agen
...
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