ASTM D7359-23

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Designation: D7359 − 18 D7359 − 23
Standard Test Method for
Total Fluorine, Chlorine and Sulfur in Aromatic
Hydrocarbons and Their Mixtures by Oxidative
Pyrohydrolytic Combustion followed by Ion
Chromatography Detection (Combustion Ion
Chromatography-CIC)
This standard is issued under the fixed designation D7359; 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*
1.1 This test method covers the individual determination of total fluorine, chlorine, and sulfur in aromatic hydrocarbons and their
mixtures. Samples containing 0.100.10 mg ⁄kg to 1010 mg mg/kg ⁄kg of each element can be analyzed.
1.2 This method can be applied to sample concentrations outside the range of the scope by dilution of the sample in an appropriate
solvent to bring the total concentrations of fluorine, chlorine, and sulfur within the range covered by the test method. However,
it is the responsibility of the analyst to verify the solubility of the sample in the solvent and that the diluted sample results conform
to the precision and accuracy of the method.
1.2.1 Special considerations must be made in order to attain detection limits below 1.01.0 mg mg/kg ⁄kg in a sample. The
instrument must be clean and properly maintained to address potential sources of contamination, of contamination, or carryover,
or both. Multiple sequential injections shall be completed until a stable background is attained. A stable background is considered
to be achieved when the analysis of a minimum of three consecutive system blanks have area counts equal to or less than 5 % RSD
for the anions of interest.
1.3 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.
1.4 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. 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.
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 Nov. 1, 2018April 1, 2023. Published December 2018April 2023. Originally approved in 2008. Last previous edition approved in 20142018 as
D7359 – 14a. DOI: 10.1520/D7359-18.18. DOI: 10.1520/D7359-23.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7359 − 23
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D3437 Practice for Sampling and Handling Liquid Cyclic Products
D3505 Test Method for Density or Relative Density of Pure Liquid Chemicals
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
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E288 Specification for Laboratory Glass Volumetric Flasks
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E969 Specification for Glass Volumetric (Transfer) Pipets
2.2 Other Documents:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Terminology
3.1 Definitions:
3.1.1 combustion ion chromatography, n—an analytical system consisting of pyrohydrolytic combustion followed by ion
chromatographic detection.
3.1.2 oxidative pyrohydrolytic combustion, n—a process in which a sample undergoes combustion at temperatures greater than
900°C900 °C in an oxygen rich oxygen-rich environment and in the presence of excess water vapor not originating from the
combustion of the sample. In oxidative pyrohydrolytic combustion, the sample is pyrolyzed into carbon dioxide, water, hydrogen
halides, and residual ash; typically elemental oxides.
3.1.3 halogens (X), n—the elements fluorine, chlorine, bromine, and iodine.
3.1.4 hydrogen halide (HX), n—are inorganic compounds with the formula HX where X is one of the halogens: fluorine, chlorine,
bromine, and iodine. Hydrogen halides are gases that dissolve in water to give acids.
3.1.5 sulfur oxide (SO ), n—refers to one or more of the following compounds:
x
3.1.5.1 sulfur dioxide (SO )
3.1.5.2 sulfur trioxide (SO )
3.1.5.3 sulfate (SO )
3.1.6 system blank, n—a combustion ion chromatography (CIC) analysis with no solvent or sample injection in which the same
combustion, chromatography and time protocols are used as for the sample analysis, but without the combustion of a sample or
solvent blank. The system blank must be equal to or less than 50 % (1/2) the area counts of the lowest calibration standard used
for calibration and a maximum of 50 % (1/2) of the area count of the solvent blank used in the preparation of the calibration
standards for the anions of interest.
3.1.7 solvent blank, n—a combustion ion chromatography (CIC) analysis of the solvent used for preparation of the calibration
standards in which the same combustion, chromatography, time protocols and injection volumes are used as for the sample
analysis. The solvent blank area count must be less than or equal to two times (2×) the system blank and 50 % (1/2) or less than
the area counts of the lowest calibration standard used in the calibration of the system for the anions of interest.
3.1.8 stock standard solution, n—standard prepared from primary standards and subsequently used to prepare the working
standard.
3.1.9 working standard solution, n—standard prepared from the stock standard solution and subsequently used to prepare the
calibration standards.
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.
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
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3.1.10 calibration standard, n—standard prepared from the working standard and subsequently used to calibrate the instrument.
3.2 Abbreviations:
3.2.1 CIC—combustion ion chromatography
3.2.2 Conc—concentration
3.2.3 CRM—certified reference material
3.2.4 HCI—hydrogen chloride
3.2.5 HF—hydrogen fluoride
3.2.6 HX—hydrogen halide
3.2.7 IC—ion chromatograph or ion chromatography
3.2.8 SO —sulfur oxide (SO and SO )
x 2 3
3.2.9 SO —sulfur dioxide
3.2.10 SO —sulfur trioxide
3.2.11 SO —sulfate
3.2.12 Std—standard
3.2.12 SRM—standard reference material
3.2.13 Std—standard
4. Summary of Test Method
4.1 A sample of known weight or volume is placed into a sample boat and introduced at a controlled rate into a high temperature
high-temperature combustion tube. There the sample is combusted in an oxygen rich pyrohydrolytic environment. The gaseous
by-products of the combusted sample are trapped in an absorption medium where the hydrogen halides (HX) formed during
- 2-
combustion disassociate into their respective ions, X while the sulfur oxides (SO ) formed are further oxidized to SO in the
X 4
presence of an oxidizing agent. An aliquot of known volume of the absorbing solution is then automatically injected into an ion
chromatograph (IC) by means of a sample injection valve. The halide and sulfate anions are separated on the anion separation
column of the IC. The conductivity of the eluent is reduced with an anion suppression device prior to the ion chromatograph’s
conductivity detector, where the anions of interest are measured. Quantification of the fluorine, chlorine and sulfur in the original
combusted sample is achieved by first calibrating the system with a series of standards containing known amounts of fluorine,
chlorine and sulfur and then analyzing unknown samples under the same conditions as the standards. The combined system of
pyrohydrolytic combustion followed by ion chromatographic detection is referred to as Combustion Ion Chromatography (CIC).
5. Significance and Use
5.1 The total fluorine, chlorine, and sulfur contained in aromatic hydrocarbon matrices can contribute to emissions, be harmful
to many catalytic chemical processes, and lead to corrosion. This test method can be used to determine total sulfur and halogens
in aromatic hydrocarbons and their mixtures. The results can be used for compliance determinations when acceptable to a
regulatory authority using performance based criteria.
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6. Interferences
6.1 Substances that co-elute with the anions of interest will interfere. A high concentration of one anion can interfere with other
constituents if their retention times are close enough to affect the resolution of their peak.
7. Apparatus
7.1 Autosampler, capable of accurately delivering a known volume of sample, typically in the range of 10 to 100 μL, 10 μL to
100 μL, into the sample boat.
NOTE 1—The sample syringe should be rinsed with clean solvent followed by a rinse with the next sample when changing from one vial to another. Follow
the manufacturer’s recommendation to minimize carryover.
7.2 Balance, analytical, with sensitivity to 0.0001 g.0.0001 g.
7.3 Boat Inlet System—The system provides a sampling port for the introduction of liquid samples into the sample boat and is
connected to the inlet of the combustion tube. The system is swept by a humidified inert carrier gas and shall be capable of allowing
the quantitative delivery of the material to be analyzed into the oxidation zone at a controlled rate.
7.4 Boat Inlet Cooler—Sample volatility requires an apparatus capable of cooling the sample boat prior to sample injection into
the boat.
7.5 Gas Flow Control—The apparatus must be equipped with flow controllers capable of maintaining a constant flow of oxygen
and argon or helium carrier gas.
7.6 Furnace—An electric furnace which can maintain a minimum temperature of 900°C.900 °C.
7.7 Gas Absorption Unit, having an absorption tube with sufficient capacity to hold a minimum of 5 mL which is automatically
filled with a known volume of absorption solution by a built-in burette or other similar device. The gas absorption unit is interfaced
to the IC and injects an aliquot of the absorption solution into the IC after the sample is combusted and the by-products of
combustion are absorbed. The gas absorption unit rinses the absorption tube and the transfer lines from the combustion tube to the
gas absorption unit with Type I reagent water (8.2) or other appropriate absorption solution prior to sample combustion and after
the absorption solution is injected into the IC to minimize cross contamination.
7.8 Gas-Tight Sampling Syringe, of 10, 25, 50, 100, or 250- μL 10 μL, 25 μL, 50 μL, 100 μL, or 250 μL capacity and capable of
accurately delivering microliter quantities.
7.9 Pyrohydrolytic Combustion Tube made of quartz and capable of withstanding temperatures up to 1100°C.1100 °C. The
combustion tube must be of ample volume and may include quartz wool or other suitable medium to provide sufficient mixing and
surface area to ensure complete combustion of the sample.
7.10 Humidifier Delivery System, capable of delivering Type 1 reagent water (8.2) to the combustion tube at a controlled rate
sufficient to provide a pyrohydrolytic environment.
7.11 Ion Chromatograph (IC),(IC) —anAn analytical system with all required accessories including columns, suppressor and
detector.
7.11.1 Injection System, capable of delivering 20 to 500 μL 20 μL to 500 μL with a precision better than 1 % or as recommended
for this determination by the manufacturer. Larger volumes can be used as long as the performance criteria of the method are not
degraded.
7.11.2 Pumping System, capable of delivering mobile phase flows between 0.20.2 mL ⁄min and 2.52.5 mL mL/min ⁄min with a
precision better than 2 %, 2 %, or as recommended for this determination by the manufacturer.
Many different companies manufacture automatic ion chromatographs. Consult the specific manufacturer instruction manuals for details regarding setup and operation.
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7.11.3 Continuous Eluent Generation (optional), to automatically prepare and purify the eluent used in the ion chromatography.
Electrolytic eluent generation and auto-buret preparation of eluent by means of in-line dilution of a stock solution have been found
satisfactory for this method. Other continuous eluent generation devices may be used if the precision and accuracy of the method
are not degraded.
7.11.4 Anion Pre-concentration Column (optional), used for anion pre-concentration and matrix elimination. Pre-concentration
enables larger volumes of absorbing solution (1 to 3 mL) solution (1 mL to 3 mL) to be analyzed without the associated water dip.
Matrix elimination refers to the elimination of any unreacted hydrogen peroxide in the absorbing solution prior to injection onto
the guard and anion separator columns and potentially interfere with the fluoride peak resolution.
7.11.5 Guard Column, for protection of the analytical column from strongly retained constituents. Improved separation is obtained
with additional theoretical plates.
7.11.6 Anion Separator Column, capable of producing satisfactory baseline separations of the anion peaks of interest as shown in
Fig. 1.
7.11.7 Anion Suppressor Device, Device—reducesReduces the background conductivity of the eluent after separation by the anion
separator column. Both chemical and continuous electrolytic suppressors have been found satisfactory for this method. Other anion
suppressor devices may be used as long as the precision and accuracy of the method are not degraded.
7.11.8 Data Acquisition System, System—anAn integrator or computer data handling system capable of integrating the peak areas
of an ion chromatographchromatograph.
7.12 Quartz or Ceramic Sample Boats of sufficient size to hold 1010 μL to 100 μL. The boat is filled with quartz wool or other
suitable material (8.3) to wick any remaining drops of the sample from the tip of the syringe needle prior to introduction of the
sample into the furnace.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade or higher purity chemicals shall be used for the preparation of all samples, standards,
eluent, and regenerator solutions. Unless otherwise indicated, it is intended that all reagents shall conform to the specification of
FIG. 1 Anion Peaks of Interest
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TABLE 1 Type I Reagent Water Key Specifications
Specification D1193–06 (2011)
Measurement (unit) Type I Type II Type III
Resistivity (M·cm) at 25°C >18 >1 >4
Resistivity (M·cm) at 25 °C >18 >1 >4
Total organic carbon (ppb) <50 <50 <200
Sodium (ppb) <1 <5 <10
Chloride (ppb) <1 <5 <10
Total silica (ppb) <3 <3 <500
the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades
may be used, provided that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the
determination.
NOTE 2—Purity of reagents are of particular importance when performing trace analysis (samples containing 11 mg mg/kg ⁄kg or less in analyte
concentration). A system reagent blank should provide a chromatographic area response no greater than 50 % 50 % (1/2) of the lowest calibration
standard.
8.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean Type 1 having 18 MΩ cm
resistance and conforming to Specification D1193. Comply with all ion chromatograph instrument and column vendor
requirements for eluent preparation and handling (for example, filtering, degassing, and the like). The reagent water is critical to
the performance, repeatability, reproducibility, and accuracy of the method. Therefore, the reagent water used must be of the
highest quality available in the lab. A chart of critical specification parameters for Type I reagent water in accordance with
Specification D1193–06 (2011) is listed in Table 1.
8.3 Quartz Wool, (fine grade) or other suitable absorbent material can be used that is stable and capable of withstanding
temperatures inside the furnace.
NOTE 3—Materials meeting the requirements in 8.3 provide a more uniform injection of the sample into the boat by wicking any remaining drops of the
sample from the tip of the syringe needle prior to introduction of the sample into the furnace. Consult instrument manufacturer recommendations for
further guidance.
8.4 Argon or Helium, carrier gas minimum 99.99 % purity.
NOTE 4—Purification scrubbers to ensure the removal of containments such as moisture (molecular sieve) and hydrocarbon trap filters (activated charcoal
or equivalent) are recommended.
8.5 Oxygen, combustion gas minimum 99.75 % purity.
8.6 Gas Regulators, Regulators—two-stage,Two-stage, gas regulators capable of regulating the pressures to 40 to 60 psi 40 psi to
60 psi must be used for the carrier and combustion gases. Follow instrument manufacturer’s recommendations for pressure
regulation.
8.7 Calibration Standards, Standards—certifiedCertified calibration standards from commercial sources or calibration standards
prepared in the laboratory containing the elements or anions at the concentrations of interest.
NOTE 5—Other calibration standard sources and diluents may be used if precision and accuracy are not degraded.
NOTE 6—Calibration standards can have a useful shelf life of about three months if properly stored in a cool, dark place.
NOTE 7—A correction for chemical impurity can be used if deemed necessary.
8.8 Dibenzothiophene, FW 184.26, 17.40 % S.
Reagent Chemicals, American Chemical Society Specifications,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.
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8.9 Fluorobenzoic Acid, Fluorobenzoic Acid, FW 140.11, 13.56 % F or Fluorobenzene, FW 96.10, 19.77% F.
8.10 2,4,5 Trichlorophenol, 2,4,5 Trichlorophenol, FW 197.46, 53.87 % Cl or Chlorobenzene, FW 112.56, 31.50 % Cl.
8.11 Hydrogen Peroxide 30 %, FW 34.01 H O (see Section 9 regarding Hazards). Purity must be suitable for trace analysis. It
2 2
is highly recommended that the concentration of each anion of interest be less than 1 mg/kg.
6 7
NOTE 8—Fluka TraceSelect Ultra, Fluka TraceSelect, and EMD Suprapur have all proven to work well for this method.
8.12 Eluent Solution—Follow the specific guidelines for the preparation and use of the eluent solution from the manufacturer of
the columns being used. Other concentrations may be used if precision and accuracy of the method is not degraded. The solutions
recommended by the column manufacturer can be purchased from qualified vendors as long as the performance, precision, and
accuracy are not degraded (see Section 9 regarding Hazards).
8.13 Suppressor Solutions:
8.13.1 Chemical Suppressor Regenerant Solution—Follow the specific manufacturer guidelines for the preparation and use of the
suppressor solution. The manufacturer recommended solutions can be purchased from qualified vendors as long as the
performance, precision, and accuracy are not degraded.
8.13.2 Electrolytic Suppressor Current Setting—Follow the specific guidelines for the current setting from the vendor of the
suppressor being used based upon the flow rate and eluent concentration being used for the analysis.
8.14 Solvent—The solvent of choice should be capable of dissolving the standard or sample. The solvent should contain less than
0.05 mg/kg of the elements or anions of interest. The blank value must be determined for each new bottle of solvent. Suggested
solvents include, but are not limited to, iso-octane, xylene, toluene, and methanol.
8.15 Volumetric Flasks–Type Class A, in accordance with Specification E288 at the volume required for the preparation of
standards, reagents, and solutions.
8.16 Volumetric Pipets–Type Class A, in accordance with Specification E969 at the volume required for preparation of standards,
reagents, and solutions.
8.17 Stock Standard Solution(s) of approximately 1000 1000 μg μg/mL—⁄mL—Prepare stock standard solution(s) by accurately
weighing to within 10 % of the target weights for any or all of the target standard compound(s) listed in 8.17.1 (choose one of the
options for Fluorine), 8.17.2 (choose one of the options for Chlorine), and 8.17.3 into a 100 mL Type Class A volumetric flask.
Dilute to volume with the selected solvent listed in 8.14. Calculate the actual concentration of the stock standard solution(s) for
each element by using the formula in Eq 1with the actual recorded weight of the target compound used for each element. This stock
standar
...