ASTM D6379-99
(Test Method)Standard Test Method for Determination of Aromatic Hydrocarbon Types in Aviation Fuels and Petroleum Distillates-High Performance Liquid Chromatography Method with Refractive Index Detection
Standard Test Method for Determination of Aromatic Hydrocarbon Types in Aviation Fuels and Petroleum Distillates-High Performance Liquid Chromatography Method with Refractive Index Detection
SCOPE
1.1 This test method covers a high performance liquid chromatographic test method for the determination of monoaromatic and di-aromatic hydrocarbon contents in aviation kerosenes and petroleum distillates boiling in the range from 50 to 300°C, such as Jet A or Jet A-1 fuels. The total aromatic content is calculated from the sum of the individual aromatic hydrocarbon-types.
Note 1-Samples with a final boiling point greater than 300°C that contain tri-aromatic and higher polycyclic aromatic compounds are not determined by this test method and should be analysed by IP 391, or other suitable equivalent test methods.
1.2 This test method is calibrated for distillates containing from 10 to 25% m/m mono-aromatic hydrocarbons and from 0 to 7% m/m di-aromatic hydrocarbons.
1.3 The precision of this test method has been established for kerosene boiling range distillates containing from 10 to 25% m/m mono-aromatic hydrocarbons and from 0 to 7% m/m di-aromatic hydrocarbons.
1.4 Compounds containing sulfur, nitrogen, and oxygen are possible interferents. Mono-alkenes do not interfere, but conjugated di- and poly-alkenes, if present, are possible interferents.
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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An American National Standard
Designation: D 6379 – 99
Designation: 436/98
Standard Test Method for
Determination of Aromatic Hydrocarbon Types in Aviation
Fuels and Petroleum Distillates – High Performance Liquid
Chromatography Method with Refractive Index Detection
This standard is issued under the fixed designation D 6379; 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.
INTRODUCTION
This test method is intended to be technically equivalent to IP 436-98 with an identical title. The
ASTM format for test methods has been used, and where possible, equivalent ASTM test methods
have replaced the IP or ISO standards.
The test method is intended to be used as one of several possible alternative instrumental test
methods that are aimed at quantitative determination of hydrocarbon types in fuels. This does not
imply that a correlation necessarily exists between this and any other test method intended to give this
information, and it is the responsibility of the user to determine such correlation if necessary.
1. Scope 1.5 This standard does not purport to address the safety
concerns, if any, associated with its use. It is the responsibility
1.1 This test method covers a high performance liquid
of the user of this standard to establish appropriate safety and
chromatographic test method for the determination of mono-
health practices and determine the applicability of regulatory
aromatic and di-aromatic hydrocarbon contents in aviation
limitations prior to use.
kerosenes and petroleum distillates boiling in the range from
50 to 300°C, such as Jet A or Jet A-1 fuels. The total aromatic
2. Referenced Documents
content is calculated from the sum of the individual aromatic
2.1 ASTM Standards:
hydrocarbon-types.
D 4057 Practice for Manual Sampling of Petroleum and
NOTE 1—Samples with a final boiling point greater than 300°C that
Petroleum Products
contain tri-aromatic and higher polycyclic aromatic compounds are not
D 4177 Practice for Automatic Sampling of Petroleum and
determined by this test method and should be analysed by IP 391, or other
Petroleum Products
suitable equivalent test methods.
2.2 IP Standards:
1.2 This test method is calibrated for distillates containing
IP 391 Determination of Aromatic Hydrocarbon Types in
from 10 to 25 % m/m mono-aromatic hydrocarbons and from
Diesel Fuels and Distillates — High Performance Liquid
0 to 7 % m/m di-aromatic hydrocarbons.
Chromatography Refractive Index Method
1.3 The precision of this test method has been established
IP 436 Test Method for Determination of Automatic Hydro-
for kerosene boiling range distillates containing from 10 to
carbon Types in Aviation Fuels and Petroleum Distillates-
25 % m/m mono-aromatic hydrocarbons and from 0 to 7 %
High Performance Liquid Chromatography Method with
m/m di-aromatic hydrocarbons.
Refractive Index
1.4 Compounds containing sulfur, nitrogen, and oxygen are
possible interferents. Mono-alkenes do not interfere, but con-
3. Terminology
jugated di- and poly-alkenes, if present, are possible interfer-
3.1 Definitions of Terms Specific to This Standard:
ents.
3.1.1 non-aromatic hydrocarbons, n—compounds that have
a shorter retention time on the specified polar column than the
mono-aromatic hydrocarbons.
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis.
Current edition approved Jan. 10, 1999. Published March 1999. Annual Book of ASTM Standards, Vol 05.02.
In the IP, this test method is under the jurisdiction of the Standardization Available from Institute of Petroleum, 61 New Canvendish St., London, W. I.,
Committee. England.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6379
3.1.2 mono-aromatic hydrocarbons (MAHs), n— com- the percent m/m MAHs and DAHs in the sample. The sum of
pounds that have a longer retention time on the specified polar the MAHs and DAHs is reported as the total aromatic content
column than the non-aromatic hydrocarbons but a shorter (percent m/m) of the sample.
retention time than the di-aromatic hydrocarbons.
3.1.3 di-aromatic hydrocarbons (DAHs), n— compounds 5. Significance and Use
that have a longer retention time on the specified polar column
5.1 Accurate quantitative information on aromatic hydro-
than the MAHs.
carbon types can be useful in determining the effects of
3.1.4 total aromatic hydrocarbons, n—sum of the MAHs
petroleum processes on production of various finished fuels.
and DAHs.
This information can also be useful for indicating the quality of
fuels and for assessing the relative combustion properties of
NOTE 2—The elution characteristics of aromatic and non-aromatic
finished fuels.
compounds on the specified polar column have not been specifically
determined for this test method. Published and unpublished data indicate
the major constituents for each hydrocarbon type as follows: (a) Non-
6. Apparatus
aromatic hydrocarbons: acyclic and cyclic alkanes (paraffins and naph-
6.1 High Performance Liquid Chromatograph (HPLC)—
thenes), mono-alkenes (if present). (b) MAHs: benzenes, tetralins, in-
Any high performance liquid chromatograph capable of pump-
danes, thiophenes, conjugated poly-alkenes. (c) DAHs: naphthalenes,
biphenyls, indenes, fluorenes, acenaphthenes, benzothiophenes. ing the mobile phase at flow rates between 0.5 and 1.5 ml/min
with a precision better than 0.5 % and a pulsation of <1 % full
4. Summary of Test Method
scale deflection under the test conditions described in Section
4.1 The sample is diluted 1:1 with the mobile phase, such as 9. See Fig. 1.
heptane, and a fixed volume of this solution injected into a high 6.2 Sample Injection System—The sample injection system
performance liquid chromatograph fitted with a polar column. shall be capable of injecting 10 μL (nominal) of sample
This column has little affinity for the non-aromatic hydrocar- solution with a repeatability better than 2 %.
bons and exhibits a pronounced selectivity for aromatic hydro- 6.2.1 An equal and constant volume of the calibration and
carbons. As a result of this selectivity, the aromatic hydrocar- sample solutions shall be injected into the chromatograph.
bons are separated from the non-aromatic hydrocarbons into Both manual and automatic sample injection systems (using
distinct bands in accordance with their ring structure, that is, either complete or partial filling of the sample loop) will, when
MAHs and DAHs. used correctly, meet the repeatability requirements laid down
4.2 The column is connected to a refractive index detector in 6.2. When using the partial loop filling mode, it is recom-
that detects the components as they elute from the column. The mended that the injection volume should be less than half the
electronic signal from the detector is continually monitored by total loop volume. For complete filling of the loop, best results
a data processor. The amplitudes of the signals (peak areas) are obtained by overfilling the loop at least six times.
from the sample aromatics are compared with those obtained 6.2.2 Sample injection volumes other than 10 μL (typically
from previously-run calibration standards in order to calculate in the range from 3 to 20 μL) may be used provided they meet
FIG. 1 Example Chromatogram of an Aviation Fuel Showing Integration Points and Aromatic Hydrocarbon Type Groups
D 6379
NOTE 7—Warning: Hydrocarbon solvents are highly flammable and
the requirements laid down for injection repeatability (see 6.2),
may cause irritation by inhalation, ingestion, or skin contact.
refractive index sensitivity and linearity (see 9.4 and 10.1), and
column resolution (see 9.4)
7.3 1-Methylnaphthalene, $ 98 % pure.
6.3 Sample Filter (Optional)—A microfilter of porosity
NOTE 8—Purity is determined by gas chromatography with flame
0.45 μm or less, which is chemically-inert towards hydrocar-
ionisation detection. The highest purity standards available should be
bon solvents, is recommended for the removal of particulate
used. Standards of $ 98 % purity are commercially available from all
matter from the sample solutions.
major suppliers.
6.4 Column System— Any stainless steel HPLC column(s) NOTE 9—Warning: Gloves should be worn when handling aromatic
compounds (for example, disposable vinyl gloves).
packed with an approved amino-bonded (or polar amino/
cyano-bonded) silica stationary phase is suitable, provided it
7.4 o-Xylene (1,2-Dimethylbenzene), $ 98 % pure.
meets the resolution requirements laid down in 9.4.3. Column
8. Sampling
lengths from 150 to 300 mm with an internal diameter from 4
to 5 mm and packed with 3 or 5 μm particle size stationary
8.1 The laboratory fuel sample from which an aliquot is
phase have been found to be satisfactory. The use of a guard being drawn for the purposes of this test method shall be
column (for example, 30 3 4.6-mm internal diameter) packed
representative of the lot of fuel. The laboratory sample should
with silica or amino-bonded silica is recommended but not
be obtained by following Practice D 4057 or D 4177, or a
essential.
similar standard.
6.5 HPLC Column Oven— Any suitable HPLC column
9. Apparatus Preparation
oven (block heating or air circulating) capable of maintaining
a constant temperature (6 1°C) within the range from 20 to 9.1 Set up the chromatograph, injection system, column and
40°C. column oven, refractive index detector, and computing inte-
grator in accordance with the appropriate equipment manuals.
NOTE 3—The refractive index detector is sensitive to both sudden and
The HPLC column shall be installed in the column oven.
gradual changes in the temperature of the eluent. All necessary precau-
tions should be taken to establish constant temperature conditions
NOTE 10—The column oven is optional if alternative arrangements are
throughout the liquid chromatograph system.
made to maintain a constant temperature environment, for example, a
NOTE 4—Alternative forms of temperature control, for example,
temperature-controlled laboratory (see 6.5).
temperature-controlled laboratories, are permitted.
9.2 Adjust the flow rate of the mobile phase to a constant 1.0
6.6 Refractive Index Detector—Any refractive index detec-
6 0.2 mL/min and ensure that the reference cell of the
tor may be used provided it is capable of being operated over
refractive index detector is full of mobile phase (see 6.6.1).
the refractive index range from 1.3 to 1.6, meets the sensitivity
Allow the temperature of the column oven (and refractive
requirement specified in 9.4.2, gives a linear response over the
index detector if equipped with temperature control) to stabi-
calibration range, and has a suitable output signal for the data
lize.
system. If the refractive index detector has a facility for
9.2.1 To minimize drift, it is essential to make sure that the
independent temperature control, it is recommended that this is
reference cell is full of solvent. The best way to accomplish this
set at the same temperature as the column oven.
is either to (1) flush the mobile phase through the reference cell
6.7 Computer or Computing Integrator—Any data system
(then isolate the reference cell to prevent evaporation of the
can be used provided it is compatible with the refractive index
solvent) immediately prior to analysis, or (2) continuously
detector, has a minimum sampling rate of 1 Hz, and is capable
make up for solvent evaporation by supplying a steady flow
of peak area and retention time measurement. The data system
through the reference cell. The make-up flow is optimized so
should also have minimum facilities for post-analysis data
that reference and analytical cell mis-match due to drying-out,
processing, such as baseline correction and re-integration. The
temperature, or pressure gradients are minimized. Typically
ability to perform automatic peak detection and identification
this can be accomplished with a make-up flow set at one tenth
and to calculate sample concentrations from peak area mea-
of the analytical flow.
surements is recommended but not essential.
NOTE 11—The flow rate may be adjusted (typically within the range
6.8 Volumetric Flasks, Grade B, or better, of 10 mL and 100
from 0.8 to 1.2 mL/min) to an optimum value to meet the resolution
mL capacity.
requirements specified in 9.4.3.
6.9 Analytical Balance, accurate to 60.0001 g.
9.3 Prepare a system resolution standard (SRS) by weighing
7. Reagents
cyclohexane (1.0 6 0.1 g), o-xylene (0.5 6 0.05 g), and
1-methylnaphthalene (0.05 6 0.005 g) into a 100 mL volumet-
7.1 Cyclohexane, >99 % pure.
ric flask and making up to the mark with heptane.
NOTE 5—Cyclohexane may contain benzene as an impurity.
NOTE 12—The SRS may be kept for up to one year if stored in a tightly
7.2 Heptane, HPLC Grade. For use as HPLC mobile phase.
stoppered bottle in a dark place between 5 and 25°C.
NOTE 6—It is recommended practice to degas the HPLC mobile phase
9.4 When operating conditions are steady, as indicated by a
before use.
stable horizontal baseline, inject 10 μL of the SRS (see 9.3) and
record the chromatogram using the data system.
NOTE 13—Baseline drift over the period of the HPLC analysis run
Stationary phases known to give suitable results include Spherisorb 3NH ,
Sphersorb 5NH , Partisil 5 PAC, and Partisphere 5 PAC. should be less than 0.5 % of the peak height for cyclohexane. A baseline
D 6379
drift greater than this indicates problems with the temperature control of
10.1.2 When operating conditions are steady (see 9.4),
the column/refractive index or polar material eluting from the column, or
inject 10 μL of Calibration Standard A. Record the chromato-
both. A period of up to 1 h may be required before the liquid chromato-
gram, and measure the peak areas for each aromatic standard.
graph reaches steady state conditions.
Ensure that baseline separation is obtained between all three
9.4.1 Ensure that baseline separation is obtained between all
components.
three components of the SRS.
10.1.3 Repeat 10.1.2 using Calibration Standards B, C, and
9.4.2 Ensure that the data system can accurately measure the
D.
peak area of 1-methylnaphthalene.
10.1.4 Plot percent m/v (g/100 mL) concentration against
area counts for each aromatic standard, that is, o-xylene and
NOTE 14—The S/N (signal to noise) ratio for 1-methylnaphthalene
1-methylnaphthalene. Calibration
...
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