ASTM D7881-13

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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 14-Aug-2013
• ICS: 71.080.40 - Organic acids
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.02 - Oxygenated Aromatics

Relations

• Referred By: ASTM D7976-14(2020) - Standard Specification for Purified Terephthalic Acid (PTA)
• Effective Date: 15-Aug-2013
• Referred By: ASTM D8062-23 - Standard Specification for Purified Terephthalic Acid (PTA) with Low <emph type="ital" >p</emph>-Toluic Acid
• Effective Date: 15-Aug-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7881 −13
Standard Test Method for
Determination of 4-Carboxybenzaldehyde and p-Toluic Acid
in Purified Terephthalic Acid by Capillary Electrophoresis
1
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.
1. Scope Procedures for Aromatic Hydrocarbons and Related Ma-
2 terials
1.1 This test method covers the determination of
E29 Practice for Using Significant Digits in Test Data to
4-carboxybenzaldehyde (4-CBA) and p-toluic acid (p-TOL) in
Determine Conformance with Specifications
purified terephthalic acid (PTA) by capillary electrophoresis
E177 Practice for Use of the Terms Precision and Bias in
(CE) with reverse voltage mode and UV detection. It is
ASTM Test Methods
applicablefor4-CBAfrom3to400mg/kgandforp-TOLfrom
E691 Practice for Conducting an Interlaboratory Study to
8 to 400 mg/kg, respectively.
Determine the Precision of a Test Method
1.2 In determining the conformance of the test results using
4
2.2 ISO Documents:
thismethodtoapplicablespecification,resultsshallberounded
EN ISO 8213 Chemical Products for Industrial Use—
off in accordance with the rounding-off method of Practice
Sampling Techniques—Solid Chemical Products in the
E29.
Form of ParticlesVarying from Powders to Coarse Lumps
1.3 The values stated in SI units are to be regarded as
5
2.3 Other Document:
standard. No other units of measurement are included in this
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
standard.
1910.1200
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 DefinitionsofTermsSpecifictoReverseVoltageModein
priate safety and health practices and determine the applica-
this Standard:
bility of regulatory limitations prior to use.
3.1.1 capillary electrophoresis, n—an electrophoretic tech-
nique in which a sample is introduced into a 50 µm to 100 µm
2. Referenced Documents
i. d. fused-silica capillary filled with electrolyte solution and
3
2.1 ASTM Standards:
subjected to high voltage for separation.
D1193 Specification for Reagent Water
3.1.1.1 Discussion—Reverse voltage, with the cathode on
D4790 Terminology ofAromatic Hydrocarbons and Related
theinjectionsideandtheanodeonthedetectionside,isapplied
Chemicals
across the capillary causing electrolyte and analytes to migrate
D6809 Guide for Quality Control and Quality Assurance
towards the anode and through the capillary’s UV detector
window. Analytes are separated based upon the differential
rates of migration in the electrical field. Analyte detection and
1
This test method is under the jurisdiction of ASTM Committee D16 on
quantitation are based upon the principles of UV detection.
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of
Subcommittee D16.02 on Oxygenated Aromatics.
3.1.2 electrolyte, n—a combination of a buffer reagent, an
Current edition approved Aug. 15, 2013. Published October 2013. DOI:
ion-pair reagent and an electroosmotic-flow modifier placed
10.1520/D7881-13.
inside the capillary, used as a carrier for the analytes, and for
2
This standard is based on SH/T 1687–2000 Purified terephthalic acid for
detection and quantitation.
industrial use—determination of 4-Carboxybenzaldehyde and p-Toluic Acid-High
performance capillary electrophoresis (HPCE), copyright SINOPEC, 22 Chaoyang-
men North Street, Chaoyang District, Beijing, China 100728. A copy of SH/T
1687–2000 may be obtained from China Petrochemical Press, www.sinopec-
4
press.com. Available from Available from American National Standards Institute (ANSI),
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
5
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D7881−13
3.1.3 electroosmotic flow (EOF), n—the directional velocity 3.1.8.1 Discussion—Nanolitres of sample are injected into
of electrolyte-solution flow within the capillary under an the capillary with analyte bias effects. It has considerable
app
...