ASTM D7360-11
(Test Method)Standard Test Method for Analysis of Benzene by Gas Chromatography with External Calibration
Standard Test Method for Analysis of Benzene by Gas Chromatography with External Calibration
SIGNIFICANCE AND USE
This test method is suitable for determining the concentrations of known impurities in finished benzene and for use as an integral quality control tool where benzene is either produced or used in a manufacturing procedure. It is generally applied to impurities such as nonaromatics containing nine carbons or less, toluene, C8 aromatics, and 1,4-dioxane.
Absolute purity cannot be determined if undetected impurities are present.
SCOPE
1.1 This test method covers the determination of normally occurring trace impurities in, and the purity of, finished benzene by gas chromatography with external calibration. A similar test method, using the internal standard technique of calibration is Test Method D4492.
1.2 This test method is applicable for nonaromatic hydrocarbon impurities at levels from 5 to 2000 mg/kg and for benzene purities of 99.80 weight % or higher.
1.3 This test method is applicable for aromatic impurities from 5 to 2000 mg/kg in benzene.
1.4 This test method has been found applicable to heteroatomic species such as 1,4-dioxane, from 10 to 2000 mg/kg in benzene.
1.5 The limit of detection for aromatic impurities is 0.9 mg/kg, 2.7 mg/kg for 1,4-dioxane and 1.1 mg/kg for methyl cyclohexane.
1.6 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 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. For specific hazard statements, see Section 9.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D7360 − 11
Standard Test Method for
Analysis of Benzene by Gas Chromatography with External
Calibration
This standard is issued under the fixed designation D7360; 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 2. Referenced Documents
1.1 This test method covers the determination of normally 2.1 ASTM Standards:
occurring trace impurities in, and the purity of, finished D3437 Practice for Sampling and Handling Liquid Cyclic
benzene by gas chromatography with external calibration. A Products
similar test method, using the internal standard technique of D3798 Test Method for Analysis of p-Xylene by Gas Chro-
calibration is Test Method D4492. matography (Withdrawn 2009)
D4307 Practice for Preparation of Liquid Blends for Use as
1.2 This test method is applicable for nonaromatic hydro-
Analytical Standards
carbon impurities at levels from 5 to 2000 mg/kg and for
D4492 Test Method for Analysis of Benzene by Gas Chro-
benzene purities of 99.80 weight % or higher.
matography
1.3 This test method is applicable for aromatic impurities
D4790 Terminology ofAromatic Hydrocarbons and Related
from 5 to 2000 mg/kg in benzene.
Chemicals
1.4 This test method has been found applicable to hetero- D6809 Guide for Quality Control and Quality Assurance
Procedures for Aromatic Hydrocarbons and Related Ma-
atomic species such as 1,4-dioxane, from 10 to 2000 mg/kg in
benzene. terials
E29 Practice for Using Significant Digits in Test Data to
1.5 The limit of detection for aromatic impurities is 0.9
Determine Conformance with Specifications
mg/kg, 2.7 mg/kg for 1,4-dioxane and 1.1 mg/kg for methyl
E177 Practice for Use of the Terms Precision and Bias in
cyclohexane.
ASTM Test Methods
1.6 In determining the conformance of the test results using
E260 Practice for Packed Column Gas Chromatography
this method to applicable specifications, results shall be
E355 Practice for Gas Chromatography Terms and Relation-
rounded off in accordance with the rounding-off method of
ships
Practice E29.
E1510 Practice for Installing Fused Silica Open Tubular
Capillary Columns in Gas Chromatographs
1.7 The values stated in SI units are to be regarded as
2.2 Other Document:
standard. No other units of measurement are included in this
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
standard.
1910.1200
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 See Terminology D4790 for definition of terms used in
priate safety and health practices and determine the applica-
this test method.
bility of regulatory limitations prior to use. For specific hazard
statements, see Section 9.
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
This test method is under the jurisdiction of ASTM Committee D16 on the ASTM website.
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of The last approved version of this historical standard is referenced on
Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their www.astm.org.
Derivatives. AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
Current edition approved June 1, 2011. Published July 2011. DOI: 10.1520/ 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
D7360–11.
www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7360 − 11
FIG. 1 Typical Chromatogram
TABLE 1 Typical Instrumental Parameters
Detector flame ionization
4. Summary of Test Method
Column: fused silica
Length 50 m
4.1 A repeatable volume of the specimen to be analyzed is
Inside diameter 0.32 mm
precisely injected into a gas chromatograph equipped with a
Stationary phase crosslinked polyethylene
glycol
flame ionization detector (FID) and a capillary column.
Film thickness 0.25 µm
4.2 The peak area of each impurity is measured. The Temperatures:
Injector 200°C
concentration of each impurity is determined using response
Detector 250°C
factor or the linear calibration curve of peak area versus
Column 70°C isothermal
concentration. Purity is calculated by subtracting the sum of Carrier gas: helium
Linear velocity 22 cm/s
the impurities found from 100.00 weight %. The concentration
Split ratio: 100:1
of impurities are reported in mg/kg. Purity of benzene is
Sample size 2.0 µL
Recorder electronic integration
reported in weight percent.
required
5. Significance and Use
5.1 This test method is suitable for determining the concen-
trations of known impurities in finished benzene and for use as
7.4 Automatic Injector—The sample must be precisely and
an integral quality control tool where benzene is either pro-
repeatably injected into the gas chromatograph. An automatic
duced or used in a manufacturing procedure. It is generally
sample injection device is highly recommended.
applied to impurities such as nonaromatics containing nine
carbons or less, toluene, C8 aromatics, and 1,4-dioxane.
8. Reagents and Materials
5.2 Absolute purity cannot be determined if undetected
8.1 Carrier Gas, 99.999 % helium or hydrogen. Concentra-
impurities are present.
tion of oxygen in the carrier should be <1 ppm, <0.5 ppm is
preferred.
6. Interferences
8.2 Detector Gases, 99.999 %—Nitrogen is recommended
6.1 Benzene is typically resolved from components with
for make up 99.999 %. Hydrogen with THC <0.5 mg/kg. Air
boiling points <138°C that normally are found in purified
with CO2, CO andTHC <1 mg/kg and oxygen between 20 and
benzene. Components normally found in purified benzene
22 %, is recommended.
include nonaromatic hydrocarbons, toluene, C8 aromatics, and
8.3 High Purity Benzene, 99.999 weight % minimum,
1,4-dioxane.An adequate separation of known impurities from
prepared by multiple step recrystallization of commercially
benzene should be evaluated for the column selected.
available 99 + weight % benzene. See AnnexA1. The benzene
must be recrystalized a minimum of three times and then
7. Apparatus
analyzed using this test method. Continue recrystalizing the
7.1 Gas Chromatograph,anychromatographhavingaflame
benzene until no impurity greater than three times the noise
ionization detector that can be operated at the conditions given
level is detected.
in Table 1.
8.4 Pure compounds for calibration should include toluene,
7.2 Electronic Integrator chromatography data system.
o-, m-, and p-xylene, ethylbenzene, methylcyclohexane, and
7.3 Column, fused silica capillary column with cross-linked 1,4-dioxane of a purity not less than 99 %. If the purity of the
polyethylene glycol stationary phase is recommended. Alter- calibration compounds is less than 99 %, the concentration and
nate stationary phases may be used if they produce at least the identification of impurities must be known so that the compo-
same aromatic separation as achieved in the chromatogram in sition of the final weighed blends can be adjusted for the
Fig. 1 and elute C nonaromatic impurities before benzene. presence of the impurities.
D7360 − 11
9. Hazards 12.5 Initially analyze the
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