ASTM D2549-23

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Designation: D2549 − 02 (Reapproved 2017) D2549 − 23
Standard Test Method for
Separation of Representative Aromatics and Nonaromatics
Fractions of High-Boiling Oils by Elution Chromatography
This standard is issued under the fixed designation D2549; 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 separation and determination of representative aromatics and nonaromatics fractions from
hydrocarbon mixtures that boil between 232 °C and 538 °C (450 °F and 1000 °F). Alternative procedures are provided for the
separation of 2 g or 10 g of hydrocarbon mixture.
NOTE 1—Some components may not be eluted from the chromatographic column for some types of samples under the conditions used in this method.
NOTE 2—Test Method D2007 is an alternative method of separating high-boiling oils into polar compounds, aromatics, and saturates fractions.
1.2 An alternative procedure is provided to handle samples boiling below 232 °C (450 °F), but whose 5 % point is above 178 °C
(350 °F) as determined by Test Method D2887. This procedure is given in Appendix X1.
1.3 The values stated in acceptable SI units are to be regarded as the standard. The values given in parentheses are provided for
information purposes only.
1.4 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 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:
D2007 Test Method for Characteristic Groups in Rubber Extender and Processing Oils and Other Petroleum-Derived Oils by the
Clay-Gel Absorption Chromatographic Method
D2425 Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
D2786 Test Method for Hydrocarbon Types Analysis of Gas-Oil Saturates Fractions by High Ionizing Voltage Mass
Spectrometry
D2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography
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
D02.04.0C on Liquid Chromatography.
Current edition approved Dec. 1, 2017March 1, 2023. Published December 2017March 2023. Originally approved in 1966. Last previous edition approved in 20122017
as D2549 – 02 (2012).(2017). DOI: 10.1520/D2549-02R17.10.1520/D2549-23.
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.
*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
D2549 − 23
D3239 Test Method for Aromatic Types Analysis of Gas-Oil Aromatic Fractions by High Ionizing Voltage Mass Spectrometry
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 aromatics fraction—fraction, n—the portion of the sample desorbed with the polar eluants. The aromatics fraction may
contain aromatics, condensed naphthenic-aromatics, aromatic olefins, and compounds containing sulfur, nitrogen, and oxygen
atoms.
3.2.2 nonaromatics fraction—fraction, n—the portion of the sample eluted with n-pentane. The nonaromatics fraction is a mixture
of paraffinic and naphthenic hydrocarbons if the sample is a straight-run material. If the sample is a cracked stock, the nonaromatics
fraction will also contain aliphatic and cyclic olefins.
4. Summary of Test Method
4.1 A weighed amount of sample is charged to the top of a glass chromatographic column packed with activated bauxite and silica
gel. n-Pentane is added to the column to elute the nonaromatics. When all of the nonaromatics are eluted, the aromatics fraction
is eluted by additions of diethyl ether, chloroform, and ethyl alcohol.
4.2 The solvents are completely removed by evaporation, and the residues are weighed and calculated as the aromatics and
nonaromatics fractions of the sample.
5. Significance and Use
5.1 The determination of compound types by mass spectrometry requires, in some instances, a preliminary separation of the
petroleum sample into representative aromatics and nonaromatics fractions, as in Test Methods D2425, D2786, and D3239. This
test method provides a suitable separation technique for this application.
6. Apparatus
6.1 Chromatographic Columns, as shown in Fig. 1. Different chromatographic columns are provided for the analysis of 2 g and
10 g samples.
6.2 Beakers, 100 mL, 250 mL, and 600 mL, inverted-rim type.
6.3 Steam Bath.
6.4 Electric Vibrator, for packing column.
6.5 Weighing Bottles or Erlenmeyer Flasks, 25 mL and 50 mL.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in this test. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not listed by the American Chemical Society, see
AnnualAnalar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial
Convention, Inc. (USPC), Rockville, MD.
D2549 − 23
FIG. 1 Chromatographic Columns
7.2 Bauxite, 20 mesh to 60 mesh. Before use, activate the bauxite by heating at 538 °C (1000 °F) for 16 h. Transfer the activated
material to an airtight container while still hot and protect thereafter from atmospheric moisture.
7.3 Chloroform. (Warning—Toxic. May be fatal if swallowed.Warning)—Toxic. May be fatal if swallowed.)
7.4 Cleaning Solution—Chromic-sulfuric acid.acid (Warning— Causes severe burns. A recognized carcinogen, strong oxidizer,
contact with organic material may cause fireWarning);— Causes severe burns. A recognized carcinogen, strong oxidizer, contact
with organic material may cause fire.) or other glassware detergents that are a homogeneous blend of sodium linear alkylaryl
sulfonate, alcohol sulfate, phosphates, and carbonates. (Warning—Toxic if swallowed.)
7.5 Diethyl Ether, anhydrous. (Warning—Extremely flammable.Warning)—Extremely flammable.) The ethyl ether used in this
test method should be free of peroxides as determined by the procedure in “Reagent Chemical, American Chemical Society
Specifications.”
The sole source of supply of the bauxite known to the committee at this time is Porocel Corp., Little Rock, AR. If you are aware of alternative suppliers, please provide
this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee , which you may
attend.
D2549 − 23
7.6 Ethyl Alcohol, denatured, conforming to Formula 2B of the U.S. Bureau of Internal Revenue. denatured. (Warning—
Flammable.Warning—)Flammable.)
7.7 Pressuring Gas, dry air or nitrogen, delivered to the top of the column at a regulated gage pressure of 0 psi to 2 psi (13.8 kPa).
(Warning—Compressed gas.Warning—)Compressed gas.)
7.8 n-Pentane, commercial grade, aromatic-free. Some samples of waxy stocks may not dissolve completely in n-pentane, in
which case cyclohexane, commercial grade, aromatic-free, may be substituted for n-pentane. (Warning—Extremely flammable
liquid.Warning—)Extremely flammable liquid.)
7.9 Silica Gel, 100 mesh to 200 mesh.
8. Procedure
NOTE 3—The procedural details differ depending on the initial boiling point of the sample. If the 5 % point is above 178 °C (350 °F), but below 232 °C
(450 °F), use procedure described in Appendix X1. If above 232 °C, continue as written depending on amount of sample to be analyzed. Instructions
specific for 2 g samples are given in 8.4.1 – 8.4.13, and instructions specific for 10 g samples are given in 8.5.1 and 8.5.8.
8.1 Select the appropriate column, depending on whether 2 g or 10 g of sample are to be analyzed. Clean the column with either
chromic-sulfuric acid (Warning—Causes severe burnsWarning—),Causes severe burns), or a glassware detergent followed by
distilled or demineralized water, acetone, and dry air or nitrogen.
8.2 Introduce a small plug of glass wool into the column, pressing it firmly into the lower end to prevent the flow of silica gel
from the column.
8.3 Clamp the column in a vertical position. Add small increments of silica gel, while vibrating the column along its length, until
the tightly packed silica gel extends to the lower mark on the chromatographic column. Continue to vibrate the column and add
bauxite until the bauxite layer extends to the upper mark on the chromatographic column. Vibrate the column for an additional
3 min after filling is completed.
8.4 If 2 g of sample are to be analyzed, continue as in 8.4.1, otherwise continue as in 8.5.
8.4.1 If the sample is viscous, warm it with intermittent mixing or shaking until it is completely fluid. Transfer a representative
sample (approximately 2 g) to a 25 mL weighing bottle or flask. Determine the mass of the sample to the nearest 1 mg by weighing
the flask before and after sample transfer. Add 10 mL of n-pentane (Warning—Extremely flammable liquid.Warning—)Extremely
flammable liquid), to the flask and dissolve the sample. If the sample does not dissolve completely in cold n-pentane, warm it in
warm water or over a steam bath. If the sample does not dissolve in warm n-pentane, take a fresh sample and substitute
cyclohexane for the n-pentane.
8.4.2 Add 10 mL of n-pentane to the top of the column to prewet the adsorbent. When the liquid level reaches the top of the
bauxite bed, transfer the sample solution from the weighing flask to the top of the column. Rinse the flask with three successive
3 mL washes of n-pentane. Add each wash to the top of the column. Then rinse the walls of the column bulb with two 3 mL
portions of n-pentane, allowing the liquid level to reach the top of the bauxite bed before adding the next portion. Finally add
35 mL of n-pentane to the column bulb.
8.4.3 Place a 50 mL graduate beneath the column to collect the eluate. The elution rate should be approximately 1 mL ⁄min.
NOTE 4—Gas pressure (Warning—Compressed gas.Warning—)Compressed gas) can be applied to the top of the column as necessary to maintain the
elution rate at approximately 1 mL ⁄min. If the correct pressure setting is known from previous runs, gas pressure may be applied after addition of the
last increment of n-pentane. Otherwise, gas pressure should be applied when n-pentane begins to elute from the column and should be adjusted to give
a flow rate of approximately 1 mL ⁄min.
The sole source of supply of the silica gel known to the committee at this time is W.R. Grace and Co., Davison Chemical Div., Baltimore, MD 21203, by specifying
Code 923. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration
at a meeting of the responsible technical committee , which you may attend.
D2549 − 23
8.4.4 When the n-pentane level reaches the top of the bauxite bed, add 80 mL of diethyl etherether. (Warning—Extremely
flammable.Warning—)Extremely flammable). Connect the pressuring gas to the top of the column and adjust the pressure to
maintain an elution rate of 1 mL ⁄min to 2 mL ⁄min.
8.4.5 Collect 50 mL of n-pentane eluate in the graduate. Rinse the tip of the column with 1 mL to 2 mL of n-pentane, adding this
to the 50 mL in the graduate (Note 5). Label the 50 mL graduate as n-pentane eluate.
NOTE 5—The n-pentane will have reached the adsorbent bed before the required volume of eluate has been collected in the 50 mL receiver. Continue
collection in this receiver after the addition of ether until the proper volume has been collected before changing to the 100 mL graduate.
8.4.6 When the ether level reaches the top of the bauxite bed, release the gas pressure and add 100 mL of chloroform
(Warning—Toxic. May be fatal if swallowed.Warning—)Toxic. May be fatal if swallowed) to the top of the column. Reconnect
the gas pressuring system and continue the elution. When 80 mL of eluate have been collected in the graduate, rinse the column
tip with 1 mL of ether and add the rinse to the 100 mL graduate. Change the receiver to a 250 mL graduate. Label the 100 mL
graduate as ether-eluted fraction.
8.4.7 When the chloroform level reaches the top of the bauxite bed, release the gas pressure and add 75 mL of ethyl
alcoholalcohol. (Warning—Flammable liquid.Warning—)Flammable liquid). Reconnect the gas pressuring system and continue
the elution until the alcohol level reaches the top of the bauxite bed. Release the gas pressure
...