ASTM D7183-07

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Designation:D7183–07
Standard Test Method for
Determination of Total Sulfur in Aromatic Hydrocarbons and
Related Chemicals by Ultraviolet Fluorescence
This standard is issued under the fixed designation D 7183; 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 2.2 Other Documents
OSHA Regulations, 29 CFR, paragraphs 1910.1000 and
1.1 This test method covers the determination of sulfur in
1910.1200
aromatic hydrocarbons, their derivatives, and related chemi-
cals.
3. Terminology
1.2 This test method is applicable to samples with sulfur
3.1 oxidative pyrolysis, n—a process in which a sample is
concentrations from 0.5 to 100 mg/kg.
combusted in an oxygen-rich atmosphere at high temperature
1.3 The following applies for the purposes of determining
to break down the components of the sample into elemental
the conformance of the test results using this test method to
oxides.
applicable specifications, results shall be rounded off in accor-
3.2 ultraviolet fluorescence, n—radiation in the region of
dance with the rounding-off method of PracticeE29.
the electromagnetic spectrum including wavelength from 100
1.4 The values stated in SI units are to be regarded as
to 3900A that excites SO to (SO *).
2 2
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.5 This standard does not purport to address all of the
4.1 A specimen is either directly injected or placed in a
safety concerns, if any, associated with its use. It is the
sample boat. The boat is then inserted into a high temperature
responsibility of the user of this standard to establish appro-
combustion tube where the sulfur is oxidized to sulfur dioxide
priate safety and health practices and determine the applica-
(SO ) in an oxygen-rich atmosphere. Water produced during
bility of regulatory limitations prior to use. For specific hazard
the sample combustion is removed and the sample combustion
statements, see Section 9.
gases are next exposed to ultraviolet (UV) light. The SO
absorbs the energy from the UV light and is converted to
2. Referenced Documents
2 excited sulfur dioxide (SO *). As it returns to a stable state,
2.1 ASTM Standards:
light is emitted and detected by a photomultiplier tube and the
D 1555 Test Method for Calculation of Volume and Weight
resulting signal is a measure of the sulfur contained in the
of Industrial Aromatic Hydrocarbons and Cyclohexane
specimen.
D 3437 Practice for Sampling and Handling Liquid Cyclic
Products
5. Significance and Use
D 6809 Guide for Quality Control and Quality Assurance
5.1 Some process catalysts used in petroleum and chemical
Procedures for Aromatic Hydrocarbons and Related Ma-
refining can be poisoned when trace amounts of sulfur-bearing
terials
materials are contained in the feedstocks. This test method can
E29 Practice for Using Significant Digits in Test Data to
be used to determine sulfur in process feeds, sulfur in finished
Determine Conformance with Specifications
products, and can also be used for purposes of regulatory
E 691 Practice for Conducting an Interlaboratory Study to
control.
Determine the Precision of a Test Method
6. Interferences
6.1 Halogens present in the specimen in concentrations
This test method is under the jurisdiction of ASTM Committee D16 on
greater than 10 % and nitrogen concentrations of 1500 mg/kg
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of
SubcommitteeD16.04 on Instrumental Analysis. or greater can interfere.
Current edition approved Jan. 15, 2007. Published April 2007.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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D7183–07
6.2 Moisture produced during the combustion step can 8.5 Dibenzothiophene—FW184.26, 17.399 % (m/m) Sulfur
interfere if not removed prior to the gas entering the detector (see Note 3).
cell.
NOTE 3—A correction for chemical impurity is required. Normally
98 %.
7. Apparatus
8.6 Quartz Wool—If needed.
7.1 Pyrolysis Furnace—An electric furnace capable of
8.7 Sulfur Stock Solution, approximately 870 to 1044 µg
maintaining a temperature sufficient to volatilize and pyrolyze
S/ml—This standard may be purchased if desired. Prepare a
all the sample and oxidize sulfur to SO . The actual tempera-
stock solution by accurately weighing approximately 0.5 to 0.6
ture should be recommended by specific instrument manufac-
g of dibenzothiophene to the nearest 0.1 mg into a tared 100
turer.
mLvolumetric flask. Record the weight. Dilute to volume with
7.2 Quartz Pyrolysis Tube—Capable of withstanding 900 to
the selected solvent. Use Eq 1 to determine the concentration
1200°C. The tube should be recommended by the instrument
of stock solution. This stock solution can be further diluted to
manufacturer.
desired sulfur concentrations (see Note 4 and Note 5). Alter-
7.3 Microlitre Syringe—Capable of delivering from 5 to
nate volumes of solutions may be prepared so long as the
250 µLof sample. Check with the instrument manufacturer for
preparation meets the concentration specified.
recommendations for specific sample requirements.
7.4 Constant Rate Injector System—If the sample is to be
~gofDBT!3~.174!3~Purity of DBT!3~10 !
µg S/ml solvent 5 (1)
introduced into the pyrolysis furnace via syringe, use a
100 ml of Solvent
constant rate injector or a liquid introduction module.
where:
7.5 Liquid Auto-Sampler—Capable of injecting 5 to 250 µL
DBT = dibenzothiophene
of sample.
SinDBT = 17.3994 %
7.6 Automatic Boat Drive System—If the instrument is
equipped with an inlet system, a device for driving the boat
NOTE 4—Working standards should be remixed on a regular basis
into the furnace at a controlled and repeatable rate is required.
depending upon frequency of use and age. Typically, stock solutions have
a useful life of about 3 months.
7.7 Flow Control—The instrument must be equipped with
flow controllers capable of maintaining a constant supply of NOTE 5—Check all new calibration standards against the previous
standard.
oxygen and carrier gas.
7.8 Drier Tube—The instrument must be equipped with a
9. Hazards
mechanism for removal of water vapor.
9.1 Consult the current version OSHA regulations, suppli-
8. Reagents
er’s Material Data Sheets, and local regulations for all mate-
8.1 Purity of Reagents—Reagent grade chemicals shall be rials used in this test method.
9.2 High temperature is employed in this test method. Extra
used in all tests. It is intended that all reagents shall conform to
the specifications of the Committee on Analytical Reagents of care must be exercised when using flammable materials near
the furnace.
theAmerican Chemical Society, where such specifications are
available, unless otherwise indicated. Other grades may be 9.3 Warning—Exposuretoexcessivequantitiesofultravio-
used, provided it is first ascertained that the reagent is of let light is injurious to health. The operator must avoid
sufficiently high purity to permit its use without lessening the exposing any part of their person, especially their eyes, not
accuracy of the determination. only to direct UV light but also to secondary or scattered
8.2 Inert Gas—Either argon (Ar) or helium (He) may be radiation that is present.
used. The purity should be no less than 99.99 mol %.
8.3 Oxygen Gas—The purity should be no less than 99.99
10. Sampling
mol %.
10.1 Consult guidelines for taking samples from bulk con-
8.4 Solvent—The solvent chosen should be capable of
tainers in accordance with Practice D 3437.
dissolving the sulfur compound. The solvent of choice should
have a boiling point similar to the sample being analyzed.
11. Preparation of Apparatus
Suggested possibilities include, but not limited to methanol,
11.1 Set-up the instrument in accordance with manufactur-
iso-octane, and p-xylene (see Note 1 and Note 2).
er’s instructions.
NOTE 1—A quick screening can be conducted by injecting the solvent
...