ASTM D5292-99(2009)
(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
SIGNIFICANCE AND USE
Aromatic content is a key characteristic of hydrocarbon oils and can affect a variety of properties of the oil including its boiling range, viscosity, stability, and compatibility of the oil with polymers.
Existing methods for estimating aromatic contents use physical measurements, such as refractive index, density, and number average molecular weight (see Test Method D 3238) or infrared absorbance and often depend on the availability of suitable standards. These NMR procedures do not require standards of known aromatic hydrogen or aromatic carbon contents and are applicable to a wide range of hydrocarbon oils that are completely soluble in chloroform at ambient temperature.
The aromatic hydrogen and aromatic carbon contents determined by this test method can be used to evaluate changes in aromatic contents of hydrocarbon oils due to changes in processing conditions and to develop processing models in which the aromatic content of the hydrocarbon oil is a key processing indicator.
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 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 standard. No other units of measurement are included in this 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 7.2 and 7.3.
General Information
Relations
Standards Content (Sample)
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: D5292 − 99(Reapproved 2009)
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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of the aro- 2.1 ASTM Standards:
matic hydrogen content (Procedures A and B) and aromatic D3238Test Method for Calculation of Carbon Distribution
carbon content (Procedure C) of hydrocarbon oils using and Structural Group Analysis of Petroleum Oils by the
high-resolution nuclear magnetic resonance (NMR) spectrom- n-d-M Method
eters. Applicable samples include kerosenes, gas oils, mineral D3701Test Method for Hydrogen Content of Aviation
oils, lubricating oils, coal liquids, and other distillates that are Turbine Fuels by Low Resolution Nuclear Magnetic
completely soluble in chloroform at ambient temperature. For Resonance Spectrometry
pulse Fourier transform (FT) spectrometers, the detection limit D4057Practice for Manual Sampling of Petroleum and
istypically0.1mol%aromatichydrogenatomsand0.5mol% Petroleum Products
aromatic carbon atoms. For continuous wave (CW) E386Practice for Data Presentation Relating to High-
spectrometers, which are suitable for measuring aromatic Resolution Nuclear Magnetic Resonance (NMR) Spec-
hydrogen contents only, the detection limit is considerably troscopy
higher and typically 0.5 mol % aromatic hydrogen atoms.
2.2 Energy Institute Methods:
IP Proposed Method BD Aromatic Hydrogen and Aromatic
1.2 The reported units are mole percent aromatic hydrogen
CarbonContentsofHydrocarbonOilsbyHighResolution
atoms and mole percent aromatic carbon atoms.
Nuclear Magnetic Resonance Spectroscopy
1.3 Thistestmethodisnotapplicabletosamplescontaining
more than 1 mass % olefinic or phenolic compounds.
3. Terminology
1.4 Thistestmethoddoesnotcoverthedeterminationofthe
3.1 Definitions of Terms Specific to This Standard:
percentage mass of aromatic compounds in oils since NMR
3.1.1 aromatic carbon content—mole percent aromatic car-
signals from both saturated hydrocarbons and aliphatic sub-
bon atoms or the percentage of aromatic carbon of the total
stituents on aromatic ring compounds appear in the same
carbon:
chemicalshiftregion.Forthedeterminationofmassorvolume
aromatic carbon content 51003 (1)
percent aromatics in hydrocarbon oils, chromatographic, or
mass spectrometry methods can be used.
aromatic carbon atoms / total carbon atoms
~ ! ~ !
1.5 The values stated in SI units are to be regarded as 3.1.1.1 Discussion—For example, the aromatic carbon con-
standard. No other units of measurement are included in this
tent of toluene is 100×(6/7) or 85.7 mol % aromatic carbon
standard. atoms.
1.6 This standard does not purport to address all of the
3.1.2 aromatic hydrogen content—mole percent aromatic
safety problems, if any, associated with its use. It is the hydrogen atoms or the percentage of aromatic hydrogen of the
responsibility of the user of this standard to establish appro-
total hydrogen:
priate safety and health practices and determine the applica-
aromatic hydrogen content 51003 (2)
bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in 7.2 and 7.3.
~aromatic hydrogen atoms!/~total hydrogen atoms!
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D02.04.0F on Absorption Spectroscopic Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 15, 2009. Published July 2009. Originally the ASTM website.
ϵ1 3
approved in 1992. Last previous edition approved in 2004 as D5292–99(2004) . Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
DOI: 10.1520/D5292-99R09. U.K.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5292 − 99 (2009)
TABLE 1 Sample and Instrument Conditions for Continuous
3.1.2.1 Discussion—For example, the aromatic hydrogen
Wave (CW) Measurements of H NMR Spectra
content of toluene is 100×(5/8) or 62.5 mol % aromatic
Solvent Chloroform-d
hydrogen atoms.
Sample concentration Up to 50 % v/v for distillable oils
Sample temperature Instrument ambient
3.2 Definitions of chemical shift (reported in parts per
Internal lock None
million (ppm)), internal reference, spectral width, and other
Sample spinning rate As recommended by manufacturer, typically 20 Hz
NMR terminology used in this test method can be found in
r-f Power level As recommended by instrument manufacturer
Practice E386. Signal to noise level A minimum of 5:1 for the maximum height of the
smaller integrated absorption band
3.3 Chloroform-d refers to chloroform solvent in which
Chemical shift reference Preferably tetramethylsilane (0.0 ppm) at no
greater than 1 vol % concentration
hydrogen is replaced by deuterium, the heavier isotope of
Integration Integrate over the range − 0.5 to 5.0 ppm for the
hydrogen. Chloroform-d is available from a variety of chemi-
aliphatic band and 5.0 to 10.0 ppm for the aromatic
cal and isotope suppliers.
band
4. Summary of Test Method
4.1 Hydrogen ( H) nuclear magnetic resonance (NMR)
suitable standards. These NMR procedures do not require
spectra are obtained on solutions of the sample in
standards of known aromatic hydrogen or aromatic carbon
chloroform-d, using a CW or pulse FT high-resolution NMR
contentsandareapplicabletoawiderangeofhydrocarbonoils
spectrometer. Carbon ( C) NMR spectra are obtained on
that are completely soluble in chloroform at ambient tempera-
solutions of the sample in chloroform-d using a pulse FT
ture.
high-resolution NMR spectrometer. Tetramethylsilane is pre-
5.3 The aromatic hydrogen and aromatic carbon contents
ferred as an internal reference in these solvents for assigning
determinedbythistestmethodcanbeusedtoevaluatechanges
the 0.0 parts per million (ppm) chemical shift position in both
1 13
in aromatic contents of hydrocarbon oils due to changes in
H and C NMR spectra.
processing conditions and to develop processing models in
4.2 The aromatic hydrogen content of the sample is mea-
which the aromatic content of the hydrocarbon oil is a key
sured by comparing the integral for the aromatic hydrogen
processing indicator.
band in the H NMR spectrum (5.0 to 10.0 ppm chemical shift
region) with the sum of the integrals for both the aliphatic
6. Apparatus
hydrogen band (−0.5 to 5.0 ppm region) and the aromatic
6.1 High-Resolution Nuclear Magnetic Resonance
hydrogen band (5.0 to 10.0 ppm region).
Spectrometer—A high-resolution continuous wave (CW) or
4.3 The aromatic carbon content of the sample is measured
pulse Fourier transform (FT) NMR spectrometer capable of
by comparing the integral for the aromatic carbon band in the
beingoperatedaccordingtotheconditionsinTable1andTable
C spectrum (100 to 170 ppm chemical shift region) with the
2andofproducingpeakshavingwidthslessthanthefrequency
sum of the integrals for both the aliphatic carbon band (−10 to
ranges of the majority of chemical shifts and coupling con-
70ppmregion)andthearomaticcarbonband(100to170ppm
stants for the measured nucleus.
region).
6.1.1 H NMR spectra can be obtained using either CW or
pulse FT techniques but C measurements require signal
4.4 The integral of the aromatic hydrogen band must be
averaging and, therefore, currently require the pulse FT tech-
corrected for the NMR absorption line due to residual chloro-
nique. Low resolution NMR spectrometers and procedures are
form (7.25 ppm chemical shift) in the predominantly
not discussed in this test method (see Test Method D3701 for
chloroform-d solvent.
an example of the use of low resolution NMR).
4.5 The integrals of the aliphatic hydrogen band and of the
6.2 Tube Tubes—Usuallya5or10mm outside diameter
aliphatic carbon band must be corrected for the NMR absorp-
tube compatible with the configuration of the CW or pulse FT
tion line due to the internal chemical shift reference tetrameth-
1 13
spectrometer.
ylsilane (0.0 ppm chemical shift in both H and C spectra).
7. Reagents and Materials
5. Significance and Use
7.1 Purity of Reagents—Reagent grade chemicals shall be
5.1 Aromatic content is a key characteristic of hydrocarbon
used in all tests. Unless otherwise indicated, it is intended that
oilsandcanaffectavarietyofpropertiesoftheoilincludingits
all reagents shall conform to the specifications of the Commit-
boiling range, viscosity, stability, and compatibility of the oil
tee onAnalytical Reagents of theAmerican Chemical Society,
with polymers.
where such specifications are available. Other grades may be
5.2 Existing methods for estimating aromatic contents use
used, provided it is first ascertained that the reagent is of
physical measurements, such as refractive index, density, and
sufficiently high purity to permit its use.
numberaveragemolecularweight(seeTestMethodD3238)or
infrared absorbance and often depend on the availability of
“Reagent Chemicals, American Chemical Society Specification.” American
Chemical Society, Washington, D.C. For suggestions on the testing of reagents not
Brandes, G., “The Structural Groups of Petroleum Fractions. I. Structural listed by the American Chemical Society, see “Analar Standards for Laboratory
GroupAnalysisWiththeHelpofInfraredSpectroscopy,” Brennstoff-ChemieVol37, U.K. Chemicals,” BDH Ltd., Poole, Dorset, and the “United States Pharmacopeia.”
1956, p. 263.
D5292 − 99 (2009)
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
Sample concentration:
8.1 It is assumed that a representative sample acquired by a
H NMR Must be optimized for the instrument in use but
procedureofPracticeD4057orequivalenthasbeenreceivedin
may be as high as 5 % v/v
C NMR Up to 50 % v/v for petroleum distillates and 30 %
the laboratory. If the test is not to be conducted immediately
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
for C NMR solutions only. Where used, a 20 mM
8.2 A minimum of approximately 10 mL of sample is
solution (about 10 mg per mL)
required for this test method. This should allow duplicate
Sample temperature Instrument ambient
Internal lock Deuterium (when chloroform-d is used for H NMR) determinations, if desired.
Sample spinning rate As recommended by manufacturer, typically 20 Hz
1 13
8.3 All samples must be homogeneous prior to subsam-
H Decoupling Only for C NMR. Broadband over the whole of
1 13
the H frequency range, gated on during C data
pling. If any suspended particles present are attributable to
acquisition only with a decoupler rise time less
foreign matter such as rust, filter a portion of the sample to be
than2m/s
tested through a small plug of glass wool, contained in a clean
Pulse flip angle Approximately 30°
Sequence delay time:
small funnel, into a clean and dry vial or NMR sample tube
HNMR>10s
containing chloroform-d.
CNMR>3swith and> 60 s without relaxation
agent
8.4 If the sample contains waxy materials, heat the sample
Memory size for Choose to give a minimum digitizing rate of 0.5
1 13
in the container to approximately 60°C and mix with a
acquisition: Hz/point for H and 1.2 Hz/point for C NMR. If
necessary, increase memory size and zero fill
high-shear mixer prior to sampling. It may be necessary to
Spectral width:
transfer a portion of the sample to an NMR tube containing
H NMR At least 15 ppm in frequency and centered, as
chloroform-d by means of a pipet which has been heated to
close as possible, to the 5 ppm chemical shift
value
approximately 60°C to maintain the homogeneity of the
C NMR At least 250 ppm in frequency and centered, as
sample.
close as possible, to the 100 ppm chemical shift
value
8.5 For a valid test result, samples must be completely
Filter bandwidth Set to be equal to or greater than the spectral
solubleinchloroform-d.Checktoensurethatthefinalsolution
width and as permitted by the instrument’s filter
hardware
is homogeneous and free of undissolved particles.
Exponential line Set at least equal to the digitizing rate
broadening
9. Procedures
Signal to noise levels:
H NMR A minimum of 20:1 for the maximum height of the
9.1 Three different procedures are described in this section
smaller integrated band
C NMR A minimum of 60:1 for the maximum height of the for determining the aromatic hydrogen content, (see 9.6)
chloroform-d resonance appearing between 75 and
ProceduresAand B (see 9.7), and the aromatic carbon content
80 ppm on the chemical shift scale
of hydrocarbon oils, Procedure C (see 9.8).
Chemical shift reference:
H NMR Preferably tetramethylsilane (0.0 ppm) at no
9.2 Theprocedureselectedbytheanalystwilldependonthe
greater than 1 vol % concentration
available NMR instrumentation and on whether an aromatic
C NMR Preferably tetramethylsilane (0.0 ppm) at no
greater than 1 vol % concentration. If this
hydrogen or aromatic carbon content is of greater value in
reference is not used, the central peak of
evaluating the characteristics of the hydrocarbon oil.
chloroform-d is set to 77.0 ppm
Integration:
9.3 Appendix X1 and Practice E386 should be used in
H NMR Integrate over the range − 0.5 to 5.0 ppm for the
conjunction with the NMR spectrometer manufacturer’s in-
aliphatic band and 5.0 to 10.0 ppm for the aromatic
band
structionsinordertoensureoptimumperformanceoftheNMR
C NMR Integrate over the range − 10 to 70 ppm for the
instrument in the application of these procedures.
aliphatic band and 100 to 170 ppm for the aromatic
band
9.4 If tetramethylsilane is used as an internal chemical shift
standard,preparea1%v/vTMSinsolventsolutionbyadding
tetramethylsilane to chloroform-d solvent. Since TMS is very
volatile, this solution should be refrigerated or replaced if the
characteristicabsorptionduetoTMSisnolongerevidentinthe
7.2 Chloroform-d—For H NMR, chloroform-d must con-
1 13
tain less than 0.2 vol % residual chl
...
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