ASTM D4492-98
(Test Method)Standard Test Method for Analysis of Benzene by Gas Chromatography
Standard Test Method for Analysis of Benzene by Gas Chromatography
SCOPE
1.1 This test method covers the determination of normally occurring trace impurities in, and the purity of, finished benzene by gas chromatography.
1.2 This test method was judged applicable for nonaromatic impurities at levels from 0.001 to 0.200 weight % and for benzene purities of 99.80 weight % or higher.
1.3 This test method is applicable for aromatic impurities from 0.001 to 0.010 weight % in benzene.
1.4 The following applies to all specified limits in this standard: for purposes of determining conformance with this standard, 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 E29.
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. For specific hazard statements, see Section 8.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: D 4492 – 98
Standard Test Method for
Analysis of Benzene by Gas Chromatography
This standard is issued under the fixed designation D 4492; 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.
1. Scope OSHA Regulations. 29 CFR, paragraphs 1910.1000 and
1910.1200
1.1 This test method covers the determination of normally
occurring trace impurities in, and the purity of, finished
3. Summary of Test Method
benzene by gas chromatography.
3.1 A known amount of an internal standard is added to the
1.2 This test method was judged applicable for nonaromatic
specimen. A small volume of this mixture is injected into a gas
impurities at levels from 0.001 to 0.200 weight % and for
chromatograph equipped with a flame ionization detector (FID)
benzene purities of 99.80 weight % or higher.
and a capillary column.
1.3 This test method is applicable for aromatic impurities
3.2 The peak area of each impurity and the internal standard
from 0.001 to 0.010 weight % in benzene.
is measured by an electronic integrator. The concentration of
1.4 The following applies to all specified limits in this
each impurity is calculated from the ratio of the peak area of
standard: for purposes of determining conformance with this
the internal standard versus the peak area of the impurity.
standard, an observed value or a calculated value shall be
Purity is calculated by subtracting the sum of the impurities
rounded off “to the nearest unit” in the last right-hand digit
found from 100.00 weight %. Results are reported in weight
used in expressing the specification limit in accordance with
percent.
the rounding-off method of Practice E 29.
1.5 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 This test method is suitable for determining the concen-
responsibility of the user of this standard to establish appro-
trations of known impurities in finished benzene and for use as
priate safety and health practices and determine the applica-
an integral quality control tool where benzene is either pro-
bility of regulatory limitations prior to use. For specific hazard
duced or used in a manufacturing procedure. It is generally
statements, see Section 8.
applied to impurities such as nonaromatics containing nine
carbons or less, toluene, C8 aromatics, and 1, 4-dioxane.
2. Referenced Documents
4.2 Absolute purity cannot be determined if unknown im-
2.1 ASTM Standards:
2 purities are present. Test Method D 852 is generally used as a
D 852 Test Method for Solidification Point of Benzene
criteria for determining the absolute purity.
D 3437 Practice for Sampling and Handling Liquid Cyclic
Products
5. Interferences
E 29 Practice for Using Significant Digits in Test Data to
5.1 Benzene is typically resolved from naturally occurring
Determine Conformance with Specifications
3 components with boiling points <138°C. Naturally occurring
E 260 Practice for Packed Column Gas Chromatography
components include nonaromatic hydrocarbons, toluene, C8
E 355 Practice for Gas Chromatography Terms and Rela-
3 aromatics, and 1, 4-dioxane. An adequate separation of known
tionships
impurities from benzene should be evaluated for the column
E 691 Practice for Conducting an Interlaboratory Test Pro-
3 selected.
gram to Determine the Precision of Test Methods
5.2 The internal standard chosen must be sufficiently re-
E 1510 Practice for Installing Fused Silica Open Tubular
3 solved from any impurity and the benzene peak.
Capillary Columns in Gas Chromatographs
2.2 Other Document:
6. Apparatus
6.1 Gas Chromatograph—Any chromatograph having a
This test method is under the jurisdiction of ASTM Committee D16 on
flame ionization detector that can be operated at the conditions
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of
given in Table 1. The system should have sufficient sensitivity
Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane, and Their
Derivatives. to obtain a minimum peak height response for a 0.0005 weight
Current edition approved Aug. 10, 1998. Published October 1998. Originally
published as D 4492 – 85. Last previous edition D 4492 – 96.
2 4
Annual Book of ASTM Standards, Vol 06.04. Available from Superintendent of Documents, U.S. Government Printing
Annual Book of ASTM Standards, Vol 14.02. Office, Washington DC 20402.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4492
TABLE 1 Typical Instrumental Parameters
the conditions described in Table 1. Allow sufficient time for
Detector flame ionization the equipment to reach equilibrium. See Practices E 260,
Column: fused silica
E 1510 and E 355 for additional information on gas chroma-
Length 50 m
tography practices and terminology.
Inside diameter 0.32 mm
Stationary phase crosslinked polyethylene glycol
Film thickness 0.25 μm
11. Calibration
Temperatures:
Injector 200°C 11.1 Prepare a synthetic mixture of high purity benzene and
Detector 250°C
representative impurities by direct weighing. Weigh each
Column 70°C isothermal
impurity to the nearest 0.1 mg. Table 2 contains a typical
Carrier gas: helium
Linear velocity 22 cm/s calibration blend. Cyclohexane is used for the nonaromatic
Split ratio: 200:1
portion and ethylbenzene for the C aromatic portion.
Sample size 0.5 μL
11.2 Using the exact weight for each impurity, calculate the
Recorder electronic integration required
weight % concentration of the calibration blend.
11.3 Into a 50-mL volumetric flask, add 50 μL of nC to
% impurity twice the height of the signal background noise. 49.95 mL of the calibration blend and mix well. Using a
6.2 Electronic Integrator, computer-based capable of han- density of 0.874 g/mL for the calibration blend and a density of
dling internal standard calculations and peak grouping is 0.718 g/mL for the nC , the resulting nC concentration will be
9 9
recommended. 0.0825 weight %.
6.3 Column, fused silica capillary column with cross-li
...
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