ASTM D7504-09
(Test Method)Standard Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and Effective Carbon Number
Standard Test Method for Trace Impurities in Monocyclic Aromatic Hydrocarbons by Gas Chromatography and Effective Carbon Number
SIGNIFICANCE AND USE
Determining the type and amount of hydrocarbon impurities remaining from the manufacture of toluene, mixed xylenes, and p-xylene used as chemical intermediates and solvents is often required. This test method is suitable for setting specifications and for use as an internal quality control tool where these products are produced or are used. Typical impurities are: alkanes containing 1 to 10 carbons atoms, benzene, toluene, ethylbenzene (EB), xylenes, and aromatic hydrocarbons containing nine carbon atoms.
This method may not detect all components and there may be unknown components that would be assigned inappropriate response factors and thus, the results may not be absolute.
SCOPE
1.1 This test method covers the determination of the total nonaromatic hydrocarbons and trace monocyclic aromatic hydrocarbons in toluene, mixed xylenes, and p-xylene by gas chromatography. The purity of toluene, mixed xylenes, or p-xylene can also be calculated. Similar test methods, using the internal standard calibration technique and the external standard calibration technique, are Test Method D 2360 and D 5917 respectively.
1.2 Total aliphatic hydrocarbons containing 1 through 10 carbon atoms (methane through decanes) can be detected by this test method at concentrations ranging from 0.0001 to 2.5000 weight %. The limit of detection is 0.00003 weight % and the limit of quantitation is 0.0001 weight %.
1.2.1 A small amount of benzene in mixed xylenes or p-xylene may not be distinguished from the non-aromatics and the concentrations are determined as a composite (see 6.1).
1.3 Monocyclic aromatic hydrocarbon impurities containing 6 through 10 carbon atoms (benzene through C10 aromatics) can be detected by this test method at individual concentrations ranging from 0.0001 to 1.0000 weight %.
1.4 The following applies to all specified limits in this test method: for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E 29.
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 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.
General Information
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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: D7504 – 09
Standard Test Method for
Trace Impurities in Monocyclic Aromatic Hydrocarbons by
Gas Chromatography and Effective Carbon Number
This standard is issued under the fixed designation D7504; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method covers the determination of the total
nonaromatic hydrocarbons and trace monocyclic aromatic
2. Referenced Documents
hydrocarbons in toluene, mixed xylenes, and p-xylene by gas
2.1 ASTM Standards:
chromatography. The purity of toluene, mixed xylenes, or
D841 Specification for Nitration Grade Toluene
p-xylenecanalsobecalculated.Similartestmethods,usingthe
D2360 Test Method for Trace Impurities in Monocyclic
internal standard calibration technique and the external stan-
Aromatic Hydrocarbons by Gas Chromatography
dard calibration technique, are Test Method D2360 and D5917
D3437 Practice for Sampling and Handling Liquid Cyclic
respectively.
Products
1.2 Total aliphatic hydrocarbons containing 1 through 10
D4534 Test Method for Benzene Content of Cyclic Prod-
carbon atoms (methane through decanes) can be detected by
ucts by Gas Chromatography
this test method at concentrations ranging from 0.0001 to
D4790 TerminologyofAromaticHydrocarbonsandRelated
2.5000 weight %. The limit of detection is 0.00003 weight %
Chemicals
and the limit of quantitation is 0.0001 weight %.
D5136 Specification for High Purity p-Xylene
1.2.1 A small amount of benzene in mixed xylenes or
D5211 Specification for Xylenes for p-Xylene Feedstock
p-xylene may not be distinguished from the non-aromatics and
D5917 Test Method for Trace Impurities in Monocyclic
the concentrations are determined as a composite (see 6.1).
Aromatic Hydrocarbons by Gas Chromatography and
1.3 Monocyclicaromatichydrocarbonimpuritiescontaining
External Calibration
6 through 10 carbon atoms (benzene through C aromatics)
D6809 Guide for Quality Control and Quality Assurance
canbedetectedbythistestmethodatindividualconcentrations
Procedures for Aromatic Hydrocarbons and Related Ma-
ranging from 0.0001 to 1.0000 weight %.
terials
1.4 The following applies to all specified limits in this test
E29 Practice for Using Significant Digits in Test Data to
method: for purposes of determining conformance with this
Determine Conformance with Specifications
test method, an observed value or a calculated value shall be
E177 Practice for Use of the Terms Precision and Bias in
rounded off “to the nearest unit” in the last right-hand digit
ASTM Test Methods
used in expressing the specification limit, in accordance with
E260 Practice for Packed Column Gas Chromatography
the rounding-off method of Practice E29.
E355 Practice for Gas Chromatography Terms and Rela-
1.5 The values stated in SI units are to be regarded as
tionships
standard. No other units of measurement are included in this
E691 Practice for Conducting an Interlaboratory Study to
standard.
Determine the Precision of a Test Method
1.6 This standard does not purport to address all of the
E1510 Practice for Installing Fused Silica Open Tubular
safety concerns, if any, associated with its use. It is the
Capillary Columns in Gas Chromatographs
responsibility of the user of this standard to establish appro-
2.2 Other Document:
1 2
This test method is under the jurisdiction of ASTM Committee D16 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Standards volume information, refer to the standard’s Document Summary page on
Derivatives. the ASTM website.
Current edition approved Jan. 15, 2009. Published February 2009. DOI: Withdrawn. The last approved version of this historical standard is referenced
10.1520/D7504-09. on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7504 – 09
TABLE 1 Recommended Method Parameters
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
1910.1200 Inlet Split
Temperature, °C 270
Column:
3. Terminology
Tubing fused silica
Length, m 60
3.1 See Terminology D4790 for definitions of terms used in
Internal diameter, mm 0.32
this test method.
Stationary phase crosslinked polyethylene
glycol
4. Summary of Test Method
Film thickness, µm 0.25
Column temperature program
4.1 The specimen to be analyzed is injected into a gas
Initial temperature, °C 60
chromatographequippedwithaflameionizationdetector(FID)
Initial time, min 10
Programming rate, °C/min 5
and a capillary column. The peak area of each component is
Final, °C 150
measured and adjusted using effective carbon number (ECN)
Time 2, min 10
response factors. The concentration of each component is
Carrier gas helium or hydrogen
Linear velocity, cm/s at 145°C 20 helium or 45 hydrocarbon
calculated based on its relative percentages of total adjusted
Split ratio 100:1
peak area and normalized to 100.0000 %.
Sample size, µL 0.6
Detector: flame ionization
5. Significance and Use
Temperature, °C 300
Analysis time, min 38
5.1 Determining the type and amount of hydrocarbon im-
purities remaining from the manufacture of toluene, mixed
xylenes, and p-xylene used as chemical intermediates and
solvents is often required. This test method is suitable for
7.3 Gas Chromatograph—Any instrument having a flame
setting specifications and for use as an internal quality control
ionization detector and a splitter injector suitable for use with
tool where these products are produced or are used. Typical
a fused silica capillary column may be used, provided the
impurities are: alkanes containing 1 to 10 carbons atoms,
system has sufficient sensitivity, linearity, and range to deter-
benzene, toluene, ethylbenzene (EB), xylenes, and aromatic
mine 0.0001 wt %, while not exceeding the full scale of either
hydrocarbons containing nine carbon atoms.
the detector or the electronic integration for the major compo-
5.2 This method may not detect all components and there
nent. It shall have a split injection system that will not
may be unknown components that would be assigned inappro-
discriminate over the boiling range of the samples analyzed.
priate response factors and thus, the results may not be
The system should be capable of operating at conditions given
absolute.
in Table 1.
7.4 Injector—The specimen must be precisely and repeat-
6. Interferences
ably injected into the gas chromatograph.An automatic sample
6.1 Insomecasesformixedxylenesand p-xylene,itmaybe
injection devise is highly recommended.
difficult to resolve benzene from the nonaromatic hydrocar-
7.5 Syringe, chromatographic, capable of delivering appro-
bons. Therefore the concentrations are determined as a com-
priate µL volumes.
posite. In the event that the benzene concentration must be
determined, an alternate method such as Test Method D4534
8. Reagents and Materials
must be selected to ensure an accurate assessment of the
8.1 Purity of Reagent—Reagent grade chemicals shall be
benzene concentration.
used in all tests. Unless otherwise indicated, it is intended that
6.2 Complete separation of ethylbenzene and m-xylene for
all reagents shall conform to the specifications of the Commit-
p-xylene is difficult and can be considered adequate if the
teeonAnalyticalReagentsoftheAmericanChemicalSociety,
distance from baseline to valley between peaks is not greater
where such specifications are available. Reagents with an
than 50 % of the peak height of the impurity.
establish purity greater than ACS reagent grade may be used.
8.2 Carrier Gas, makeup gas and detector gases 99.999 %
7. Apparatus
pure. Oxygen in carrier gas less than 1 ppm, less than 0.5 ppm
7.1 Chromatographic data system is required.
is preferred. Purify carrier, makeup and detector gases to
7.2 Columns—The choice of column is based on resolution
remove oxygen, water, and hydrocarbons.
requirements. Any column may be used that is capable of
8.3 Air for the FID should contain less than 0.1 ppm total
resolving all significant impurities from the major component.
hydrocarbon.
The column and conditions described in Table 1 have been
8.4 Calibration check standard. This standard may be
used successfully and shall be used as a referee in cases of
purchased if desired.
dispute.
4 6
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments, Reagent Chemicals, American Chemical Society Specifications, American
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
www.access.gpo.gov. listed by the American Chemical Society, see Analar Standards for Laboratory
Scanlon. J. T. and Willis, D. E., “Calculation of Flame Ionization Detector Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Relative Response Factors Using the Effective Carbon Number Concept,” Journal and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
of Chromatographic Science, Vol. 3
...
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