ASTM D4901-99(2020)

Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts

SIGNIFICANCE AND USE
4.1 The concentration of tannin in extracts must be reduced to analytical strength (4 g tannin per L) for analysis.  
4.2 Vegetable tannin extracts are heterogeneous mixtures of components with varying solubility.  
4.3 The solubility of such extracts is influenced by temperature and concentration, which affect the degree of dispersion and size of the component particles.  
4.4 While the solubility is better in hot water than in cold water, it is appropriate to dissolve and disperse an extract in hot water and then let the solution cool slowly to standard room temperature.
SCOPE
1.1 This practice covers the preparation of a solution of liquid extract that is to be used in the tannin analysis of that extract.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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.  
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: 30-Nov-2020
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.01 - Vegetable Leather

Relations

• Refers: ASTM D4904-99(2009) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2009
• Refers: ASTM D6404-99(2009) - Standard Practice for Sampling Vegetable Materials Containing Tannin
• Effective Date: 01-Apr-2009
• Refers: ASTM D4904-99(2004) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
• Effective Date: 01-Apr-2004
• Refers: ASTM D6404-99(2004) - Standard Practice for Sampling Vegetable Materials Containing Tannin
• Effective Date: 01-Apr-2004
• Refers: ASTM D4904-99 - Standard Practice for Cooling of Analytical Solutions
• Effective Date: 10-May-1999
• Refers: ASTM D6404-99 - Standard Practice for Sampling Vegetable Materials Containing Tannin
• Effective Date: 10-May-1999

Overview

ASTM D4901-99(2020) - Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts provides standardized guidance for preparing analytical-strength solutions from liquid vegetable tannin extracts. Tannin extracts, commonly used in industries such as leather processing, are complex mixtures with varying solubilities. This standard ensures accurate preparation of solutions for tannin analysis, promoting consistency and reliability in laboratory and industrial practices.

Developed by ASTM International, this standard supports globally recognized best practices and facilitates compliance with international trade regulations as stipulated by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Key Topics

• Analytical Preparation: The standard specifies reducing the tannin concentration in extracts to 4 g tannin per liter, which is optimal for analytical work.
• Solubility Factors: It highlights the heterogeneous nature of vegetable tannin extracts and how temperature and concentration influence their solubility and dispersion.
• Dissolution Process: Dissolving extracts in hot water (at least 80°C) results in better solubility before cooling to room temperature. Gentle mixing and the use of proper laboratory glassware are recommended.
• Specimen Handling: Guidance is provided for sampling (referencing Practice ASTM D6404) and preparing specimens, including recommendations for using volumetric flasks and handling viscous extracts with mechanical stirring instead of hand shaking.
• Preventing Fermentation: For extracts prone to fermentation, the addition of formaldehyde and toluene is suggested to inhibit mold and ensure solution integrity during the cooling phase.
• Duplicate Preparation: The document permits the preparation of duplicate solutions to verify analytical consistency.

Applications

ASTM D4901-99(2020) is valuable to laboratories, quality control departments, and manufacturing facilities involved in:

• Leather tanning and processing: Accurate tannin analysis is crucial for process control and product quality.
• Plant extract research and development: Standardized solution preparation enables reliable comparative studies.
• Food and beverage industry: For products where tannins impact quality or require regulatory compliance.
• Academic laboratories: Supports reproducible experiments and teaching of proper analytical solution preparation.
• International trade compliance: Standardized practices enhance reliability for regulatory, export, and import requirements.

By following ASTM D4901, organizations can ensure the reliability and comparability of analytical results, reduce the risk of errors due to inconsistent preparation techniques, and support transparency in product claims related to tannin content.

Related Standards

• ASTM D6404 - Practice for Sampling Vegetable Materials Containing Tannin: Provides protocols for obtaining representative samples.
• ASTM D4904 - Practice for Cooling of Analytical Solutions: Details how to properly cool analytical solutions, as referenced in D4901.
• ALCA Method A10 - Preparation of Solution of Liquid Extracts: Foundation for the development of ASTM D4901 and relevant for legacy methods.
• Other relevant analytical chemistry standards: For quality control and laboratory best practices in the preparation and handling of analytical solutions.

Keywords: ASTM D4901, tannin analysis, vegetable tannin extract, analytical solution preparation, laboratory standard, solubility, leather industry, quality control, international standards.

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: D4901 − 99 (Reapproved 2020)
Standard Practice for
Preparation of Solution of Liquid Vegetable Tannin Extracts
This standard is issued under the fixed designation D4901; 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 4. Significance and Use
1.1 This practice covers the preparation of a solution of 4.1 The concentration of tannin in extracts must be reduced
liquid extract that is to be used in the tannin analysis of that to analytical strength (4 g tannin per L) for analysis.
extract.
4.2 Vegetable tannin extracts are heterogeneous mixtures of
1.2 The values stated in SI units are to be regarded as components with varying solubility.
standard. No other units of measurement are included in this
4.3 The solubility of such extracts is influenced by tempera-
standard.
ture and concentration, which affect the degree of dispersion
1.3 This standard does not purport to address all of the
and size of the component particles.
safety concerns, if any, associated with its use. It is the
4.4 While the solubility is better in hot water than in cold
responsibility of the user of this standard to establish appro-
water,itisappropriatetodissolveanddisperseanextractinhot
priate safety, health, and environmental practices and deter-
water and then let the solution cool slowly to standard room
mine the applicability of regulatory limitations prior to use.
temperature.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Apparatus and Reagents
ization established in the Decision on Principles for the
5.1 Formaldehyde—40 % solution.
Development of International Standards, Guides and Recom-
5.2 Toluene—assay ≥ 99.5 %.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5.3 Flask,1Lvolumetric.TheClassAtype,withupperbulb
in neck, is especially suitable for this work.
2. Referenced Documents
6. Test Specimen
2.1 ASTM Standards:
D4904 Practice for Cooling of Analytical Solutions
6.1 The specimen shall consist of an aliquot of the sample,
D6404 Practice for Sampling Vegetable Materials Contain-
prepared as described in Practice D6404, sufficient to give a
ing Tannin
solution containing as nearly as possible,4gof tannin per L
2.2 ALCA Methods:
(not less than 3.75 g, nor more than 4.25 g, per L).
A10 Preparation of Solution of Liquid Extracts
7. Procedure
3. Summary of Practice
7.1 Prepare samples of liquid extracts as described in
3.1 This practice describes a technique found useful in the
Practice D6404, and allow to come to room temperature.
preparation of analytical strength solutions from samples of
Thoroughly mix at room temperature and transfer specimen to
liquid vegetable tannin extracts.
a tared container and stoppered to prevent loss of moisture.
Return no material which has been removed from the sample
This practice is under the jurisdiction ofASTM Committee D31 on Leather and for any other purpose (for example, for determination of
is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This
specific gravity, etc.) to the sample. Care must be taken that
practicehasbeenadaptedfrom,andisareplacementfor,MethodA10oftheOfficial
dried material around the neck of the stopper of the sample
Me
...