ASTM D7881-20e1

Standard Test Method for Determination of 4-Carboxybenzaldehyde and <emph type="bdit" >p</emph>-Toluic Acid in Purified Terephthalic Acid by Capillary Electrophoresis with Reverse Voltage Mode

SIGNIFICANCE AND USE
5.1 The presence of 4-CBA and p-TOL in PTA used for the production of polyester is undesirable because they can slow down the polymerization process; and 4-CBA is also imparting coloration to the polymer due to thermal instability.  
5.2 Determining the amount of 4-CBA and p-TOL remaining from the manufacture of PTA is often required. This test method is suitable for setting specifications and for use as an internal quality control where these products are produced or used.  
5.3 This test method is intended as an alternative to the HPLC method for the determination of 4-CBA and p-TOL in PTA. The major benefits of CE are speed, simplicity, reduced reagent consumption, and operating costs.
SCOPE
1.1 This test method2 covers the determination of 4-carboxybenzaldehyde (4-CBA) and p-toluic acid (p-TOL) in purified terephthalic acid (PTA) by capillary electrophoresis (CE) with reverse voltage mode and UV detection. It is applicable for 4-CBA from 3 to 400 mg/kg and for p-TOL from 8 to 400 mg/kg, respectively.  
1.2 In determining the conformance of the test results using this method to applicable specification, results shall be rounded off in accordance with the rounding-off method of Practice E29.  
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.  
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: 30-Sep-2020
• ICS: 71.080.40 - Organic acids
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.02 - Oxygenated Aromatics

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.
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Designation:D7881 −20
Standard Test Method for
Determination of 4-Carboxybenzaldehyde and p-Toluic Acid
in Purified Terephthalic Acid by Capillary Electrophoresis
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with Reverse Voltage Mode
This standard is issued under the fixed designation D7881; 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.
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ε NOTE—Research report information in Section 14 was updated editorially in February 2021.
1. Scope* 2. Referenced Documents
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2
2.1 ASTM Standards:
1.1 This test method covers the determination of
D1193 Specification for Reagent Water
4-carboxybenzaldehyde (4-CBA) and p-toluic acid (p-TOL) in
D6809 Guide for Quality Control and Quality Assurance
purified terephthalic acid (PTA) by capillary electrophoresis
Procedures for Aromatic Hydrocarbons and Related Ma-
(CE) with reverse voltage mode and UV detection. It is
terials
applicablefor4-CBAfrom3to400mg/kgandforp-TOLfrom
E29 Practice for Using Significant Digits in Test Data to
8 to 400 mg/kg, respectively.
Determine Conformance with Specifications
1.2 In determining the conformance of the test results using
E691 Practice for Conducting an Interlaboratory Study to
thismethodtoapplicablespecification,resultsshallberounded
Determine the Precision of a Test Method
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off in accordance with the rounding-off method of Practice
2.2 ISO Documents:
E29.
EN ISO 8213 Chemical Products for Industrial Use—
Sampling Techniques—Solid Chemical Products in the
1.3 The values stated in SI units are to be regarded as
Form of ParticlesVarying from Powders to Coarse Lumps
standard. No other units of measurement are included in this
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2.3 Other Document:
standard.
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
1.4 This standard does not purport to address all of the
1910.1200
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3. Terminology
priate safety, health, and environmental practices and deter-
3.1 DefinitionsofTermsSpecifictoReverseVoltageModein
mine the applicability of regulatory limitations prior to use.
this Standard:
1.5 This international standard was developed in accor-
3.1.1 capillary electrophoresis, n—an electrophoretic tech-
dance with internationally recognized principles on standard-
nique in which a sample is introduced into a 50 µm to 100 µm
ization established in the Decision on Principles for the
i. d. fused-silica capillary filled with electrolyte solution and
Development of International Standards, Guides and Recom- subjected to high voltage for separation.
mendations issued by the World Trade Organization Technical 3.1.1.1 Discussion—Reverse voltage, with the cathode on
theinjectionsideandtheanodeonthedetectionside,isapplied
Barriers to Trade (TBT) Committee.
across the capillary causing electrolyte and analytes to migrate
towards the anode and through the capillary’s UV detector
window. Analytes are separated based upon the differential
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This test method is under the jurisdiction of ASTM Committee D16 on
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-
bility of Subcommittee D16.02 on Oxygenated Aromatics.
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Current edition approved Oct. 1, 2020. Published December 2020. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 2013. Last previous edition approved in 2019 as D7881 – 19. DOI: contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
10.1520/D7881-20E01. Standards volume information, refer to the standard’s Document Summary page on
2
This standard is based on SH/T 1687–2000 Purified terephthalic acid for the ASTM website.
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industrial use—determination of 4-Carboxybenzaldehyde and p-Toluic Acid-High Available from Available from American National Standards Institute (ANSI),
performance capillary electrophoresis (HPCE), copyright SINOPEC, 22 Chaoyang- 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
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men North Street, Chaoyang District, Beijing, China 100728. A copy of SH/T AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
1687–2000 may be obtained from China Petrochemical Press, www.sinopec- 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
press.com. 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
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