ASTM D3876-96(2021)

Standard Test Method for Methoxyl and Hydroxypropyl Substitution in Cellulose Ether Products by Gas Chromatography

SIGNIFICANCE AND USE
3.1 This test method determines the methoxyl and hydroxypropoxyl content of cellulose ethers by a Zeisel-gas chromatographic technique.  
3.2 Substitution levels affect solution properties, rheology, viscosity, and many other properties of the polymer.
SCOPE
1.1 This test method is applicable to the determination of methoxyl and hydroxypropyl substitution content in cellulose ether products by a Zeisel-gas chromatographic technique.  
1.2 This test method is not suitable for use for the analysis of hydroxypropyl-cellulose due to its very high substitution level.  
1.3 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 2, 11.1.4, and 11.1.7.  
1.4 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-May-2021
• ICS: 85.040 - Pulps
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.36 - Cellulose and Cellulose Derivatives

Overview

ASTM D3876-96(2021): Standard Test Method for Methoxyl and Hydroxypropyl Substitution in Cellulose Ether Products by Gas Chromatography defines a precision test method to determine the levels of methoxyl and hydroxypropoxyl substitution in cellulose ethers. Substitution levels in these polymers significantly impact their property profiles, including solution behavior, viscosity, rheology, and usability in various applications. This method employs a Zeisel-gas chromatographic technique, providing reliable quantitative data essential for quality control, research, and development in industries utilizing cellulose ether products.

Key Topics

• Scope and Applicability

  • Determines methoxyl and hydroxypropoxyl content in cellulose ether products.
  • Utilizes a Zeisel-gas chromatography approach for accurate quantification.
  • Excludes hydroxypropyl-cellulose due to its high substitution level.

• Principle of the Method

  • Cellulose ethers are reacted with hydriodic acid, releasing methyl iodide and isopropyl iodide proportional to the respective substitution groups.
  • The liberated alkyl iodides are extracted and measured by gas chromatography.
  • An internal standard (toluene in o-xylene) facilitates quantitative analysis.

• Instrumentation and Materials

  • Requires a gas chromatograph with a thermal conductivity detector, heated injection port, and suitable packed columns.
  • Reaction vials, syringes, and reagent-grade chemicals are essential for accurate sample processing.

• Safety Considerations

  • Proper safety, health, and environmental practices must be established by users.
  • Special care must be taken when handling hydriodic acid and during pressurized, high-temperature reactions.

• Precision and Reliability

  • Demonstrates good relative precision, especially in determining methoxyl and hydroxypropoxyl levels.
  • Ensures consistent and reproducible results when performed under prescribed conditions.

Applications

• Quality Control:
  Regulatory compliance and quality assurance in the production of cellulose ethers-controlling substitution levels ensures product consistency, effectiveness, and safety.

• Product Development and Research:
  Formulation scientists and polymer chemists rely on accurate methoxyl and hydroxypropoxyl profiling when designing cellulose ether-based products for diverse industries, including:

  • Pharmaceuticals (drug delivery systems, excipients)
  • Food additives (thickeners, stabilizers)
  • Construction materials (cement modifiers)
  • Paints and coatings (viscosity modifiers)

• Technical Support and Complaint Resolution:
  Used as a reference method in addressing product performance issues attributed to improper substitution levels.

Related Standards

• ASTM D1347 - Standard Test Method for Methoxyl Groups in Sodium Carboxymethylcellulose
• ASTM D1439 - Standard Test Methods for Sodium Carboxymethylcellulose
• ASTM D2363 - Standard Test Method for Determination of Degree of Substitution in Cellulose Acetate
• ISO/TC 61 - Plastics: International standards for testing and analyzing polymeric materials

ASTM D3876-96(2021) aligns with internationally recognized best practices for the development, validation, and adoption of test methods, as endorsed by the World Trade Organization Technical Barriers to Trade (TBT) Committee. This assures broad acceptance and facilitates global trade and regulatory approval for materials tested using this standard.

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Keywords: methoxyl substitution, hydroxypropyl substitution, cellulose ethers, gas chromatography, Zeisel method, polymer analysis, ASTM D3876, quality control, cellulose derivative testing

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: D3876 − 96 (Reapproved 2021)
Standard Test Method for
Methoxyl and Hydroxypropyl Substitution in Cellulose Ether
Products by Gas Chromatography
This standard is issued under the fixed designation D3876; 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 3.2 Substitution levels affect solution properties, rheology,
viscosity, and many other properties of the polymer.
1.1 This test method is applicable to the determination of
methoxyl and hydroxypropyl substitution content in cellulose
4. Apparatus
ether products by a Zeisel-gas chromatographic technique.
4.1 Gas Chromatograph, with thermal conductivity detec-
1.2 This test method is not suitable for use for the analysis
tor and heated injection port.
of hydroxypropyl-cellulose due to its very high substitution
4.2 Electronic Integrator.
level.
1.3 This standard does not purport to address all of the 4.3 Stainless Steel Tubing, 9.5 mm in outside diameter and
safety concerns, if any, associated with its use. It is the 1981 mm in length, packed with reagent in 5.8.
responsibility of the user of this standard to establish appro-
4.4 Syringes, 10 and 100 µL.
priate safety, health, and environmental practices and deter-
4.5 Reaction Vials, Caps, and Heating Block.
mine the applicability of regulatory limitations prior to use.
For specific hazard statements, see Section 2, 11.1.4, and
5. Reagents
11.1.7.
1.4 This international standard was developed in accor- 5.1 Purity of Reagents—Reagent grade chemicals shall be
dance with internationally recognized principles on standard- used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. used, provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
2. Summary of Test Method accuracy of the determination.
5.2 o-Xylene, ACS.
2.1 When methyl cellulose or hydroxypropyl methyl cellu-
lose is reacted with hydriodic acid, 1 mol of methyl iodide and
5.3 Toluene, ACS.
1 mol of isopropyl iodide are liberated for each mole of
5.4 Iodomethane, 99 % min.
methoxyl and hydroxypropoxyl that is substituted on the
cellulose chain. The methyl iodide and isopropyl iodide are 5.5 2-Iodopropane, 97 % min.
extracted in situ with o-xylene and quantitated by gas chroma-
5.6 Hydriodic Acid (sp. gr. 1.69 to 1.70)57%.
tography using an internal standard technique.
3. Significance and Use
Hewlett-Packard Model 5700, available from Hewlett-Packard, Route 41, Starr
Rd,P.O.Box900,Avondale,PA19311,hasbeenfoundsatisfactoryforthispurpose.
3.1 This test method determines the methoxyl and hydroxy-
Hewlett-Packard Model 3380 has been found satisfactory for this purpose.
propoxyl content of cellulose ethers by a Zeisel-gas chromato-
Tubing from Supelco, Inc., Supelco Park, Bellefonte, PA16823 has been found
graphic technique.
satisfactory for this purpose.
Reacti-therm Heating module, Reacti-Block Reacti-vials and Mininert valve
tops from Pierce Chemical Co., Box 117, Rockford, IL 61105 have been found
satisfactory for this purpose.
1 6
This test method is under the jurisdiction of ASTM Committee D01 on Paint ACS Reagent Chemicals, Specifications and Procedures for Reagents and
and Related Coatings, Materials, andApplications and is the direct responsibility of Standard-Grade Reference Materials, American Chemical Society, Washington,
Subcommittee D01.36 on Cellulose and Cellulose Derivatives. DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Current edition approved June 1, 2021. Published June 2021. Originally Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
approved in 1979. Last previous edition approved in 2013 as D3876 – 96 (2013). U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
DOI: 10.1520/D3876-96R21. copeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3876 − 96 (2021)
5.7 Acetone. 9.2.4 Add 30 µL of isopropyl iodide to the vial through the
7 septum top with a syringe. Weigh and record the amount of
5.8 Packing Material.
isopropyl iodide added to nearest 0.1 mg.
9.2.5 Add 90 µLof methyl iodide to the vial with a syringe.
6. Hazards
Weigh and record the amount added to nearest 0.1 mg.
6.1 Safety precautions must be taken for handling of hydri-
9.2.6 Mix the contents well.
odic acid.
9.2.7 Convert the alkyl iodides into their respective alkoxyl
6.2 During the reaction, the glass vials are under pressure.
equivalents using the following equations:
Exercise caution in handling the hot vials.
31 31000
mg methoxyl 5 g methyl iodide 3 (1)
S D
7. Sampling
75 31000
7.1 A specific sampling method is currently under study by
mg hydroxy propoxyl 5 g propyliodide 3 (2)
S D
the subcommittee.
mg toluene 5 internal standard solution concentrated 34 ml (3)
8. Apparatus Preparation and Conditioning
10. Calibration of Electronic Integrator
8.1 Install prepackaged columns in the chromatograph and
condition them by heating to 150°C over 1 h and then holding
10.1 Inject 1 µL of the upper layer of the prepared standard
at temperature for 16 h. Then set the chromatograph as
solution (9.2) into the gas chromatograph and start the elec-
follows: tro
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