ASTM D7183-23

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Designation: D7183 − 18a (Reapproved 2023) D7183 − 23
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 D7183; 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 determination of sulfur in aromatic hydrocarbons, their derivatives, and related chemicals.
1.2 This test method is applicable to samples with sulfur concentrations to 10 mg/kg. The limit of detection (LOD) is 0.03 mg/kg
S and the limit of quantitation (LOQ) is 0.1 mg/kg S. With careful analytical technique, this method can be used to successfully
analyze concentrations below the current scope (see Appendix X1).
NOTE 1—LOD and LOQ were calculated using data in ASTM Research Report RR:D16-1060.
1.3 The following applies for the purposes of determining the conformance of the test results using this test method to applicable
specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific hazard statements, see Section 9.
1.6 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:
D1555 Test Method for Calculation of Volume and Weight of Industrial Aromatic Hydrocarbons and Cyclohexane
D3437 Practice for Sampling and Handling Liquid Cyclic Products
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsibility of
Subcommittee D16.04 on Instrumental Analysis.
Current edition approved Jan. 1, 2023May 1, 2023. Published January 2023May 2023. Originally approved in 2007. Last previous edition approved in 20182023 as
ɛ1
D7183 – 18a . DOI: 10.1520/D7183-18AR23.(2023). DOI: 10.1520/D7183-23.
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
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D7183 − 23
2.2 Other Documents
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Terminology
3.1 oxidative pyrolysis, n—a process in which a sample is combusted in an oxygen-rich atmosphere at high temperature to break
down the components of the sample into elemental oxides.
3.2 ultraviolet fluorescence, n—radiation in the region of the electromagnetic spectrum including wavelength from 100 to 3900A
that excites SO to (SO *).
2 2
4. Summary of Test Method
4.1 A specimen is either directly injected or placed in a sample boat. The boat is then inserted into a high temperature combustion
tube where the sulfur is oxidized to sulfur dioxide (SO ) in an oxygen-rich atmosphere. Water produced during the sample
combustion is removed and the sample combustion gases are next exposed to ultraviolet (UV) light. The SO absorbs the energy
from the UV light and is converted to excited sulfur dioxide (SO *). As it returns to a stable state, light is emitted and detected
by a photomultiplier tube and the resulting signal is a measure of the sulfur contained in the specimen.
5. Significance and Use
5.1 Some process catalysts used in petroleum and chemical refining can be poisoned when trace amounts of sulfur-bearing
materials are contained in the feedstocks. This test method can be used to determine sulfur in process feeds, sulfur in finished
products, and can also be used for purposes of regulatory control.
6. Interferences
6.1 Halogens present in the specimen in concentrations greater than 10 % and nitrogen concentrations of 1500 mg/kg or greater
can interfere.
6.2 Moisture produced during the combustion step can interfere if not removed prior to the gas entering the detector cell.
7. Apparatus
7.1 Combustion Furnace—An electric furnace capable of maintaining a temperature sufficient to volatilize and combust all the
sample and oxidize sulfur to SO . The actual temperature should be recommended by specific instrument manufacturer.
7.2 Quartz Combustion Tube—Capable of withstanding 900 °C to 1200 °C. The tube should be recommended by the instrument
manufacturer.
7.3 Microlitre Syringe—Capable of delivering from 5 μL to 250 μL of sample. Check with the instrument manufacturer for
recommendations for specific sample requirements.
7.4 Constant Rate Injector System—If the sample is to be introduced into the pyrolysis furnace via syringe, use a constant rate
injector or a liquid introduction module.
7.5 Liquid Auto-Sampler—Capable of injecting 5 μL to 250 μL of sample.
7.6 Automatic Boat Drive System—If the instrument is equipped with an inlet system, a device for driving the boat into the furnace
at a controlled and repeatable rate is required.
7.7 Flow Control—The instrument must be equipped with a means of flow control capable of maintaining a constant supply of
oxygen and carrier gas or air.
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7.8 Drier Tube—The instrument must be equipped with a mechanism for removal of water vapor.
8. Reagents
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. 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, unless otherwise indicated. 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.
8.2 Inert Gas or Air—Either argon (Ar), helium (He) or air may be used. The purity should be no less than 99.99 %.
8.3 Oxygen Gas (as required)—The purity should be no less than 99.99 %.
8.4 Solvent—The solvent chosen should be capable of dissolving the sulfur compound. The solvent of choice should have a boiling
point similar to the sample being analyzed. Suggested possibilities include, but not limited to methanol, iso-octane, and p-xylene
(see Note 2 and Note 3).
NOTE 2—A quick screening can be conducted by injecting the solvent and sample once or twice and comparing relative area counts.
NOTE 3—All solvents should have known sulfur content or known to be less than what will interfere with results.
8.5 Dibenzothiophene—FW184.26, 17.399 % (m/m) Sulfur (see Note 4).
NOTE 4—A correction for chemical impurity is required. Normally 98 %.
8.6 Quartz Wool—If needed.
8.7 Sulfur Stock Solution, approximately 870 μg to 1044 μg S/ml—This standard may be purchased if desired. Prepare a stock
solution by accurately weighing approximately 0.5 g to 0.6 g of dibenzothiophene to the nearest 0.1 mg into a tared 100 mL
volumetric flask. Record the weight. Dilute to volume with the selected solvent. Use Eq 1 to determine the concentration of stock
solution. This stock solution can be further diluted to desired sulfur concentrations (see Note 5 and Note 6). Alternate volumes of
solutions may be prepared so long as the preparation meets the concentration specified.
g of DBT × .174 × Purity of DBT × 10
~ ! ~ ! ~ ! ~ !
μg S/ml solvent 5 (1)
100 ml of Solvent
where:
DBT = dibenzothiophene
S in DBT = 17.3994 %
NOTE 5—Working standards should be remixed on a regular basis depending upon frequency of use and age. Typically, stock solutions have a useful life
of about 3 months.
NOTE 6—Check all new calibration standards against the previous standard.
8.8 Oxidation Reagent (as required)—Tungsten trioxide, (WO ), granular (typical particle size >2.0 mm), high purity, 99.75 %
minimum.
9. Hazards
9.1 Consult the current version OSHA regulations, supplier’s Data Sheets, and local regulations for all materials used in this test
method.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, American Chemical Society, Washington, DC. For
suggestions on the testing of reagents not listed by the American Chemical Society, see Analar 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.
D7183 − 23
9.2 High temperature is employed in this test method. Extra care must be exercised when using flammable materials near the
furnace.
9.3 Warning—Exposure to excessive quantities of ultraviolet light is injurious to health. The operator must avoid exposing any
part of their person, especially their eyes, not only to direct UV light but also to secondary or scattered radiation that is present.
10. Sampling
10.1 Consult guidelines for taking samples from bulk containers in accordance with Practice D3437.
11. Preparation of Apparatus
11.1 Set-up the instrument in accordance with manufacturer’s instructions.
11.2 Adjust gas flows and pyrolysis temperature(s) to the operating conditions recommended by the manufacturer.
11.3 The actual operation of injecting a sample will vary depending upon the instrument manufacturer and the type of inlet system
used.
11.4 An autosampler or a constant rate injector must be used when using an instrument equipped with a vertical furnace.
11.5 Prebake the sample boats to be used for the determination when using a horizontal furnace.
12. Calibration and Standardization
12.1 Using the sulfur standard stock solution (see 8.7), make a series of calibrations standards covering the range of expected
sulfur concentration.
NOTE 7—When looking for levels of sulfur below 1 mg/kg make a calibration curve using an autosampler or constant rate injector and standards, made
from the sulfur stock solution, to cover the expected range of samples. Follow manufacturer’s recommendations for constructing the curve.
NOTE 8—When looking for concentrations from 1 mg S/kg to 10 mg S/kg, follow manufacturer’s recommendations for constructing the curve.
12.2 The sample size can be determined either volumetrically, by syringe or by mass.
12.3 Volumetric measurement can be utilized by filling the syringe with standard, carefully eliminating all bubbles, and pushing
the plunger to a calibrated mark on the syringe, and recording the volume of liquid in the syringe. After injecting the standard, read
the volume remaining in the syringe. The difference between the two volume readings is the volume of standard injected. This test
method requires the known or measured density, to the third decimal place.
12.4 Alternatively, the syringe may be weighed before and after the injection to determine the weight of the sample injected. This
technique provides greater precision than the volume delivery method, provided a balance with a precision of 60.0001 g is used.
12.5 F
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