ASTM D4590-22

Standard Test Method for Colorimetric Determination of <emph type="ital">p-tert</emph >-Butylcatechol In Styrene Monomer or AMS (α–Methylstyrene) by Spectrophotometry

SIGNIFICANCE AND USE
5.1 This test method is suitable for determining the quantity of TBC inhibitor, both for the protection against polymerization while in transit and storage, and for internal quality control.
SCOPE
1.1 This test method is applicable to the determination of residual 4-tertiary-butylcatechol (TBC) in styrene monomer or AMS in the 1 mg/kg to 100 mg/kg range.  
1.2 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. The limit of detection is 0.2 mg/kg while the limit of quantitation is 0.8 mg/kg based on the ILS data in Table 1.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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 statements on hazards, see Section 9.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-Oct-2022
• ICS: 17.180.20 - Colours and measurement of light
• ICS: 71.080.60 - Alcohols. Ethers
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.07 - Styrene, Ethylbenzene and C9 and C10 Aromatic Hydrocarbons

Relations

• Refers: ASTM D6809-02(2016) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Nov-2016
• Refers: ASTM D4790-14 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 01-Jul-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D4790-11 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 01-Feb-2011
• Refers: ASTM D3437-11 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jan-2011
• Refers: ASTM D3437-10 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jun-2010
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E29-08 - Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
• Effective Date: 01-Oct-2008
• Refers: ASTM D3437-08 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jun-2008
• Refers: ASTM D4790-07 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 15-Jul-2007
• Refers: ASTM D6809-02(2007) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Jun-2007
• Refers: ASTM E29-06b - Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
• Effective Date: 15-Nov-2006
• Refers: ASTM E29-06a - Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
• Effective Date: 15-Sep-2006
• Refers: ASTM E29-06 - Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
• Effective Date: 01-May-2006

Overview

ASTM D4590-22 sets out the standard test method for the colorimetric determination of p-tert-butylcatechol (TBC) in styrene monomer and alpha-methylstyrene (AMS) by spectrophotometry. This widely referenced standard provides a reliable chemical analysis technique for measuring the residual TBC inhibitor content, which is critical for preventing unwanted polymerization during transportation and storage, as well as for internal quality control in the chemical industry.

The method is applicable for TBC concentrations in the range of 1 mg/kg to 100 mg/kg, with a detection limit of 0.2 mg/kg and a quantitation limit of 0.8 mg/kg. Only SI units are used in this standard.

Key Topics

• Purpose of Analysis: Ensures that the levels of TBC, a key polymerization inhibitor, are accurately monitored in styrene monomer and AMS to maintain quality and safety during handling.
• Scope of Application: Suitable for routine quality assurance and specification conformance, especially for manufacturers and users of styrene and AMS.
• Method Overview:
  • A caustic solution in a methanol-octanol solvent is used to develop a color reaction with TBC.
  • The developed color is measured at 490 nm using a spectrometer.
  • The TBC content is determined by comparing sample absorbance to a calibration curve.
• Addressing Interferences: Compounds that also produce color at 490 nm when contacted with sodium hydroxide may interfere. Known interferences, if present in the sample, can be accounted for through preparation of the standard solutions.
• Precision and Bias: The standard includes defined limits for repeatability and reproducibility. Proficiency testing across multiple laboratories is encouraged to ensure credible results.
• Safety Considerations: Users are responsible for adequate safety, health, and environmental practices, as hazardous chemicals and flammable materials are involved.

Applications

ASTM D4590-22 is integral to:

• Quality Control in Production: Used routinely in chemical manufacturing facilities to confirm TBC levels in styrene monomer or AMS meet product specifications and regulatory guidelines.
• Supply Chain and Transportation: Ensures that inhibitors are at sufficient levels to prevent polymerization during shipping and storage, safeguarding against hazardous reactions and product spoilage.
• Regulatory Compliance: Supports compliance with industry standards and governmental safety requirements for handling and transporting bulk monomer products.
• Inter-Laboratory Comparability: Encourages the use of quality control samples and proficiency testing, promoting the consistency and reliability of results across laboratories and between product batches.

Related Standards

This test method references and complements several ASTM and regulatory standards critical to accurate and safe analysis:

• ASTM D1193 – Specification for Reagent Water: Ensures water quality for test methods.
• ASTM D3437 – Practice for Sampling and Handling Liquid Cyclic Products: Guides proper sampling techniques.
• ASTM D4790 – Terminology of Aromatic Hydrocarbons and Related Chemicals: Provides definitions for key terms.
• ASTM D6809 – Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons: Outlines best practices for QA/QC.
• ASTM E29 – Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications: Specifies data rounding rules.
• OSHA 29 CFR 1910.1000 and 1910.1200 – Provide regulatory guidelines on exposure limits and safety measures.

By adhering to ASTM D4590-22, laboratories and manufacturers can maintain high standards for inhibitor content in styrene and alpha-methylstyrene, enhancing product quality and operational safety across the supply chain.

Standards Content (Sample)

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.
Designation: D4590 − 22
Standard Test Method for
Colorimetric Determination of p-tert-Butylcatechol In Styrene
Monomer or AMS (α–Methylstyrene) by Spectrophotometry
This standard is issued under the fixed designation D4590; 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* D4790 Terminology ofAromatic Hydrocarbons and Related
Chemicals
1.1 This test method is applicable to the determination of
D6809 Guide for Quality Control and Quality Assurance
residual 4-tertiary-butylcatechol (TBC) in styrene monomer or
Procedures for Aromatic Hydrocarbons and Related Ma-
AMS in the 1 mg⁄kg to 100 mg⁄kg range.
terials
1.2 In determining the conformance of the test results using
E29 Practice for Using Significant Digits in Test Data to
this method to applicable specifications, results shall be
Determine Conformance with Specifications
rounded off in accordance with the rounding-off method of
E691 Practice for Conducting an Interlaboratory Study to
Practice E29. The limit of detection is 0.2 mg/kg while the
Determine the Precision of a Test Method
limit of quantitation is 0.8 mg/kg based on the ILS data in
2.2 Other Document:
Table 1.
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
1910.1200
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Terminology
standard.
3.1 See Terminology D4790 for definition of terms used in
1.4 This standard does not purport to address all of the
this standard.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Method
priate safety, health, and environmental practices and deter-
4.1 Color is developed in the specimen by the addition of
mine the applicability of regulatory limitations prior to use.
caustic in a methanol-octanol solvent.The intensity of the pink
For specific statements on hazards, see Section 9.
color is measured with a spectrometer and compared to a
1.5 This international standard was developed in accor-
calibration curve for quantitation.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 5. Significance and Use
Development of International Standards, Guides and Recom-
5.1 This test method is suitable for determining the quantity
mendations issued by the World Trade Organization Technical
of TBC inhibitor, both for the protection against polymeriza-
Barriers to Trade (TBT) Committee.
tion while in transit and storage, and for internal quality
control.
2. Referenced Documents
6. Interferences
2.1 ASTM Standards:
D1193 Specification for Reagent Water
6.1 Any other compound producing color at 490 nm when
D3437 Practice for Sampling and Handling Liquid Cyclic
contacted with aqueous sodium hydroxide solution will inter-
Products fere. It may be compensated for by including it in the
preparation of the standard solutions, if its identity and
concentration in the sample are known.
This test method is under the jurisdiction of ASTM Committee D16 on
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-
7. Apparatus
bility of Subcommittee D16.07 on Styrene, Ethylbenzene and C9 and C10Aromatic
7.1 Visible Range Spectrometer, equipped with absorption
Hydrocarbons.
Current edition approved Nov. 1, 2022. Published November 2022. Originally
cells providing light paths from 1 cm to 5 cm for use at
approved in 1986. Last previous edition approved in 2018 as D4590 – 18. DOI:
approximately 490 nm.
10.1520/D4590-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
Standards volume information, refer to the standard’s Document Summary page on 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
the ASTM website. www.access.gpo.gov.
*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
D4590 − 22
7.2 Volumetric Pipets and Pipetors—The sample pipet vol- 8.9 Purity of Water—Unless otherwise indicated, references
ume should be sized to fill the spectrometer absorption cell. to water shall be understood to mean any reagent conforming
Pipetor volumes must be scaled to the sample volume. This to type I as defined in Specification D1193.
procedure is written using a 15 mL sample volume. The
9. Hazards
following table shows how reagent pipetor volumes could be
scaled to usea5mL sample volume. See 8.7 for the 9.1 Consult current OSHA regulations, supplier’s Safety
preparation of 0.15 N NaOH.
Data Sheets, and local regulations for all materials used in this
test method.
Sample Pipet, 0.15 N NaOH Methanol Pipetor,
mL Pipetor, µL
9.2 Handling Precautions—p-tert-butylcatechol, particu-
µL
15 300 600
larlywhenmoltenorinconcentratedsolution,isverycorrosive
5 100 200
to the skin. It is also a systemic poison when taken orally or
absorbed in quantity through the skin.
8. Reagents and Materials
9.3 Flammable Hazards—Styrene monomer is flammable
8.1 Purity of Reagents—Reagent grade chemicals shall be
andcanpolymerizeexothermallyunderavarietyofconditions,
used in all tests. Unless otherwise indicated, it is intended that
mostespeciallyinthepresenceofperoxides,mineralacids,and
allreagentsshallconformtothespecificationoftheCommittee
Lewis acids such as aluminum chloride.
on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades may be 10. Sampling and Handling
used, provided it is first ascertained that the reagent is of
10.1 Sample the material in accordance with Practice
sufficiently high purity to permit its use without lessening the
D3437.
accuracy of the determination.
11. Preparation of Calibration Curve
8.2 4-Tertiary-Butylcatechol, Mp 52 °C to 55 °C, CAS 98-
11.1 Prepare standards of approximately 5 mg⁄kg,
29-3.
10 mg⁄kg, 20 mg⁄kg, 30 mg⁄kg, 40 mg⁄kg, 50 mg⁄kg,
8.3 Toluene, ACS reagent grade, CAS 108-88-3.
70 mg⁄kg, and 100 mg⁄kg TBC in toluene by diluting 0.5 mL,
1 mL, 2 mL, 3 mL, 4 mL, 5 mL, 7 mL, and 10 mL of TBC
8.4 Methanol, reagent grade, CAS 67-56-1.
stock standard to 100 mL with toluene. Record the actual
8.5 n-Octanol, reagent grade, CAS 111-87-5.
concentrations generated to the nearest 0.5 mg/kg.
8.6 Aqueous Sodium Hydroxide, 10 Normal (10N), reagent
NOTE 1—Both the stock solution and toluene diluent should be at room
grade, CAS 1310-73-2.
temperature. Temperature differences will cause dilution errors due to
variations in density.
8.7 Alcoholic Sodium Hydroxide, approximately 0.15 N:
11.2 Determine the absorbance of each standard solution
Mix 0.75 mLof 10 NAqueous Sodium Hydroxide with 25 mL
and one reagent blank in accordance with Section 12.
methanol. With stirring, add 25 mL of n-octanol and then
0.75 mL of water. Store the reagent in an amber glass bottle.
11.3 Plot absorbance versus concentration on standard
This reagent can be used immediately after preparation and is graph paper.
stable for at least 2 months. To reduce exposure of the reagent
NOTE 2—The plot should be close to a straight line. The maximum
to the atmosphere, transfer enough for several samples to a
absorbance should be within the absorbance range of the spectrometer. If
small clean vial.
not, repeat the calibration with a spectrometer cell that has less path
length.
8.8 TBC Stock Standard—This standard may be purchased
if desired. Prepare a stock solution by w
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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: D4590 − 18 D4590 − 22
Standard Test Method for
Colorimetric Determination of p-tert-Butylcatechol In Styrene
Monomer or AMS (α–Methylstyrene) by Spectrophotometry
This standard is issued under the fixed designation D4590; 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 is applicable to the determination of residual 4-tertiary-butylcatechol (TBC) in styrene monomer or AMS in
the 11 mg ⁄kg to 100100 mg mg/kg range. Any other compound producing color at 490 nm when contacted with aqueous sodium
hydroxide solution will interfere. It may be compensated for by including it in the preparation of the standard solutions, if its
identity and concentration in the sample are known.⁄kg range.
1.2 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. The limit of detection is 0.2 mg/kg while the limit of quantitation
is 0.8 mg/kg based on the ILS data in Table 1.Table 1.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 statements on hazards, see Section 89.
1.5 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
D4790 Terminology of Aromatic Hydrocarbons and Related 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
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Other Document:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
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 June 1, 2018Nov. 1, 2022. Published June 2018November 2022. Originally approved in 1986. Last previous edition approved in 20132018 as
D4590 – 13.D4590 – 18. DOI: 10.1520/D4590-18.10.1520/D4590-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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.
*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
D4590 − 22
TABLE 1 Intermediate Precision and Reproducibility
TBC Observed
Concentration, Repeatability Reproducibility
mg/kg
4.7 0.23 0.94
15.2 0.47 5.08
24.5 1.55 4.91
94.6 3.98 9.94
3. Terminology
3.1 See Terminology D4790 for definition of terms used in this standard.
4. Summary of Method
4.1 Color is developed in the specimen by the addition of caustic in a methanol-octanol solvent. The intensity of the pink color
is measured with a spectrometer and compared to a calibration curve for quantitation.
5. Significance and Use
5.1 This test method is suitable for determining the quantity of TBC inhibitor, both for the protection against polymerization while
in transit and storage, and for internal quality control.
6. Interferences
6.1 Any other compound producing color at 490 nm when contacted with aqueous sodium hydroxide solution will interfere. It may
be compensated for by including it in the preparation of the standard solutions, if its identity and concentration in the sample are
known.
7. Apparatus
7.1 Visible Range Spectrometer, equipped with absorption cells providing light paths from 11 cm to 5 cm 5 cm for use at
approximately 490 nm.
7.2 Volumetric Pipets and Pipetors—The sample pipet volume should be sized to fill the spectrometer absorption cell. Pipetor
volumes must be scaled to the sample volume. This procedure is written using a 15 mL sample volume. The following table shows
how reagent pipetor volumes could be scaled to use a 5 mL sample volume. See 8.7 for the preparation of 0.15 N NaOH.
Sample Pipet, 0.15 N NaOH Methanol Pipetor,
mL Pipetor, μL
μL
15 300 600
5 100 200
8. Reagents and Materials
8.1 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 specification of the Committee on Analytical Reagents of the American Chemical Society, where such
specifications are available. 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 4-Tertiary-Butylcatechol, Mp 52 to 55°C.52 °C to 55 °C, CAS 98-29-3.
8.3 Toluene, ACS reagent grade.grade, CAS 108-88-3.
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.
D4590 − 22
8.4 Methanol, reagent grade.grade, CAS 67-56-1.
8.5 n-Octanol, reagent grade.grade, CAS 111-87-5.
8.6 Aqueous Sodium Hydroxide, 10 Normal (10N), reagent grade.grade, CAS 1310-73-2.
8.7 Alcoholic Sodium Hydroxide, approximately 0.15 N: Mix 0.75 mL of 10N 0.75 mL of 10 N Aqueous Sodium Hydroxide with
25 mL methanol. With stirring, add 25 mL of n-octanol and then 0.75 mL 0.75 mL of water. Store the reagent in an amber glass
bottle. This reagent can be used immediately after preparation and is stable for at least 2 months. To reduce exposure of the reagent
to the atmosphere, transfer enough for several samples to a small clean vial.
8.8 TBC Stock Standard—This standard may be purchased if desired. Prepare a stock solution by weighing 0.5000.500 g 6 0.001
g of TBC to the nearest 0.0001 g into 500500 g 6 1 g of toluene (weighed to the nearest 0.1 g). This solution will have a
concentration of approximately 1000 mg/kg TBC in toluene and the exact concentration can be calculated using Eq 1. This
standard should have a shelf life of one year or better if stored in a refrigerator or freezer. Storing standards in amber bottles
significantly reduces degradation of standards with time.
mg TBC/kg toluene 5 @~g of TBC! 3~Purity of TBC! 3~10 !#/g of toluene (1)
8.9 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean any reagent conforming to type
I as defined in Specification D1193.
9. Hazards
9.1 Consult current OSHA regulations, supplier’s Safety Data Sheets, and local regulations for all materials used in this test
method.
9.2 Handling Precautions—p-tert-butylcatechol, particularly when molten or in concentrated solution, is very corrosive to the
skin. It is also a system
...