ASTM D8063-18

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:D8063 −18
Standard Test Method for
Water in Purified Terephthalic Acid (PTA) by Volumetric Karl
Fischer Titration
This standard is issued under the fixed designation D8063; 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 Determine Conformance with Specifications
E177 Practice for Use of the Terms Precision and Bias in
1.1 This test method covers the determination of water in
ASTM Test Methods
purified terephthalic acid (PTA) between 0.01 and 1.00 %
E203 Test Method for Water Using Volumetric Karl Fischer
(w⁄w) by Volumetric Karl Fischer Titration.
Titration
1.2 In determining the conformance of the test results using
E300 Practice for Sampling Industrial Chemicals
thismethodtoapplicablespecification,resultsshallberounded
E691 Practice for Conducting an Interlaboratory Study to
off in accordance with the rounding-off method of Practice
Determine the Precision of a Test Method
E29. 3
2.2 Other Document:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 1910.1200
standard.
3. Summary of Test Method
1.4 This standard does not purport to address all of the
3.1 A PTA sample is dissolved in a solvent (mixture of
safety concerns, if any, associated with its use. It is the
methanolandpyridine,intherangeof30~35 %methanoland
responsibility of the user of this standard to establish appro-
70 ~ 65 % pyridine) and titrated with Karl Fischer reagent,
priate safety, health, and environmental practices and deter-
which consists of iodine, sulfur dioxide, methanol and an
mine the applicability of regulatory limitations prior to use.
organic base.
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard- 3.2 In the Karl Fischer reaction, water will react with iodine
ization established in the Decision on Principles for the according to the following equation:
Development of International Standards, Guides and Recom-
H O1I 1SO 13RN1CH OH→2RNHI1RNHSO CH
2 2 2 3 4 3
mendations issued by the World Trade Organization Technical
3.3 The volume of Karl Fischer reagent consumed to titrate
Barriers to Trade (TBT) Committee.
the sample is converted into the amount of water in the test
PTA sample.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
D1193 Specification for Reagent Water
4.1 The presence of water in PTAused for the production of
D4790 Terminology ofAromatic Hydrocarbons and Related
polyester is undesirable because it reduces the purity of the
Chemicals
PTA.
D6809 Guide for Quality Control and Quality Assurance
4.2 Determining the amount of water content remaining
Procedures for Aromatic Hydrocarbons and Related Ma-
from the manufacture of PTA is often required. This test
terials
method is suitable for setting product specifications and for use
E29 Practice for Using Significant Digits in Test Data to
as an internal quality control tool where these products are
produced or are used.
This test method is under the jurisdiction of ASTM Committee D16 on
5. Interference
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-
bility of Subcommittee D16.02 on Oxygenated Aromatics. 5.1 Certain compounds or classes of compounds interfere
Current edition approved Jan. 1, 2018. Published May 2018. DOI: 10.1520/
with the accurate determination of water by the Karl Fischer
D8063-18.
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 Available from U.S. Government Printing Office, Superintendent of
Standards volume information, refer to the standard’s Document Summary page on Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://
the ASTM website. www.access.gpo.gov.
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D8063−18
NOTE1—Ifwatercontentinpyridineormethanolishigherthan0.05 %,
test method. They include aldehydes, ketones, free halogens,
50 g 5A may be added to 500 mL pyridine or methanol for desiccation.
ferric salts and strong oxidizing and reducing agents.
8. Hazards
6. Apparatus
8.1 Consult current federal regulations, supplier’s Safety
6.1 Karl Fischer Volumetric Titrator, consisting of a titra-
Data Sheets, and local regulations for all materials used in this
tion cell, dual platinum electrode, magnetic stirrer, dispensing
test method.
burette (2 or 5 mL) and control unit.Any Karl Fischer Titrator
capable of performing Volumetric Karl Fischer titrations with
9. Sampling
an electrometric end-point detector can be used in this method.
9.1 Use only representative samples obtained as described
6.2 Microlitre Syringe, 10 µL.
in Practice E300, unless otherwise specified. Care must be
6.3 Pipette, 10 mL.
taken to eliminate the introduction of water from sampling
equipment and atmospheric moisture.
6.4 Analytical Balance, capable of weighing to the nearest
0.0001 g accurately.
9.2 Sample containers should be dry, sealed.
9.3 The amount of PTA sample added into the titration cell
7. Reagents and Materials
is dependent upon the quantity of water in the sample. Table 1
7.1 Purity of Reagents—Reagent grade chemicals shall be
shows the recommended sample size. Other sample size may
used in all tests. Unless otherwise indicated, it is intended that
be used as long as the dissolution of PTA in the pyridine-
all reagents shall conform to the specifications of theAmerican
methanol mixed solvent is not compromised.
Chemical Society, where such specifications are available.
Other grades may be used, provided it is first ascertained that
10. Preparation of Apparatus
the reagent is of sufficiently high purity to permit its use
10.1 Followthemanufacturer’sdirectionsforpreparationof
without lessening the accuracy of the determination.
the titration apparatus.
7.2 Water—Unless otherwise indicated, references to water
shall be understood to mean reagent water conforming to Type 11. Standardization
II of Specification D1193.
11.1 Standardize the Karl Fischer reagent daily or as nec-
7.3 Karl Fischer Reagent (one component)—may be pre- essary.
pared in the laboratory or purchased, containing imidazole or
11.2 Add an appropriate amount of pyridine-methanol
pyridine, methanol, iodine and sulfur dioxide. The use of
mixed solvent to the clean, dry titration vessel to cover the
pyridine-freereagentsisrecommended.Thesereagentsareless
electrodes. The volume of solvent depends on the size of the
toxic, less odorous, and more stable than those containing
titration vessel and sample amount. The 50 mLsolvent size for
pyridine. The water equivalence of the Karl Fischer reagent is
1 g sample and the recommended titer of the Karl Fischer
1 to 2 mg/mL. (Warning—KF reagent contains toxic com-
reagent listed in Table 1 has been found to be satisfactory for
pounds. It should be dispensed in a well-ventilated area. Care
testing water in PTA and can be used as a guideline
must be exercised to avoid inhalation of the reagent or direct
11.3 All joints and connections to the cell shall be sealed in
contact of the reagent with the skin.)
order to prevent atmospheric moisture from entering the
7.4 Pyridine—Less than 0.05 % (w/w) water. (Warning—
titration cell. Select a stirring speed that is sufficient to create
odorous and harmful if inhaled, swallowed or absorbed
a well-defined vortex with the solvent.
through the skin. Perform operations in a hood to avoid
11.4 Pre-titrate the solvent according to the instrument
pyridine fumes.).
manufacturer’s instructions so that all the moisture has been
7.5 Methanol—Less than 0.05 % (w/w) water. (Warning—
removed prior to introduction of the sample.
highly flammable and harmful. May be fatal or cause blindness
11.5 Standardize the Karl Fischer reagent with water by the
if swallowed or inhaled.)
following method:
7.6 Pyridine-Methanol Mixed Solvent—in the range
...