ASTM D2340-23

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D2340 − 18 D2340 − 23
Standard Test Method for
Peroxides in Styrene Monomer
This standard is issued under the fixed designation D2340; 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 determination of the peroxide content of styrene monomer reported as hydrogen peroxide.
1.2 This test method has been found applicable to the determination of peroxides in styrene monomer in the range of 11 mg ⁄kg
to 60 mg/kg. Based on the precision data in 12.1, LOD is 6 mg ⁄kg and LOQ is 21 mg/kg.
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 Units—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 7.
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:
D1193 Specification for Reagent Water
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
2.2 Other Documents:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Summary of Test Method
3.1 A specimen of styrene monomer is added to a solution of isopropanol and acetic acid. A saturated solution of sodium iodide
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 D16.07 on Styrene, Ethylbenzene and C9 and C10 Aromatic Hydrocarbons.
Current edition approved Jan. 1, 2018Jan. 1, 2023. Published January 2018January 2023. Originally approved in 1965. Last previous edition approved in 20132018 as
D2340 – 13.D2340 – 18. DOI: 10.1520/D2340-18.10.1520/D2340-23.
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*A Summary of Changes section appears at the end of this standard
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D2340 − 23
in isopropanol is added and the solution refluxed. The peroxides present liberate iodine from sodium iodide quantitatively. The
liberated iodine is then titrated with sodium thiosulfate to a colorless end point.
4. Significance and Use
4.1 This test method is suitable for determining the quantity of peroxides in styrene monomer both for quality control and quality
assurance of the product.
5. Apparatus
5.1 Erlenmeyer Flasks, glass-stoppered, 500-mL,500 mL, equipped with 300-mm300 mm Liebig condensers having inner and
outer standard taper joints.
5.2 Electric Hot Plate with totally enclosed heating unit.
5.3 Boiling Chips.
6. Reagents
6.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, 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. Other 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.
6.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type
IIIII of Specification D1193.
6.3 Glacial Acetic Acid. CAS 64-19-17
6.4 Isopropyl Alcohol. CAS 63-67-0
6.5 Sodium Iodide Iodide (CAS 7681-82-5) Isopropyl Alcohol Solution—Prepare a saturated solution of sodium iodide in
isopropanol (approximately 200 g NaI/L).
6.6 Sodium Thiosulfate, Thiosulfate,(CAS 7772-98-7) Standard Solution (0.01 N Na S O )—Dissolve 2.5 g of sodium thiosulfate
2 2 3
(Na S O · 5H O) and 0.1 g of sodium carbonate (Na CO ) in water and dilute to 1 L. Standardize against primary standard
2 2 3 2 2 3
potassium dichromate (K Cr O ).
2 2 7
6.7 Alternate volumes of solutions may be prepared so long as the preparation meets the concentration specified.
7. Hazards
7.1 Consult the latest OSHA regulations, supplier’s Safety Data Sheets, and local regulations regarding all materials used in this
test method.
7.2 Styrene monomer is flammable and polymerizes exothermally on contact with peroxides, mineral acids, and aluminum
chloride.
7.3 Isopropyl alcohol is flammable and should be kept away from open flame and spark-producing apparatus. Use only a hot plate
with totally enclosed heating unit in this analysis.
Reagent Chemicals,
...