ASTM D3898-93(2023)

Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors

SIGNIFICANCE AND USE
4.1 The procedure described is for the quality control for manufacturing liquors and specifications for the purchase of such liquors.  
4.2 The chromium content of the liquors determines the amount to be used to obtain the desired degree of tannage, and hence may be a matter for specification in the purchase of leather.
SCOPE
1.1 This test method covers the determination of chromic oxide in chrome tanning liquors, either simple, with added aluminum or zirconium, or with the usual masking complexing agents.  
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-2023
• ICS: 59.140.10 - Processes and auxiliary materials
• Technical Committee: D31 - Leather
• Drafting Committee: D31.06 - Chemical Analysis

Relations

• Replaces: ASTM D3898-93(2015) - Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
• Effective Date: 01-Dec-2023
• Referred By: ASTM D5356-17a - Standard Test Method for pH of Chrome Tanning Solutions
• Effective Date: 01-Dec-2023
• Referred By: ASTM D3913-03(2020)e1 - Standard Test Method for Acidity in Basic Chromium Tanning Liquors
• Effective Date: 01-Dec-2023
• Referred By: ASTM D3897-18 - Standard Test Method for Calculation of Basicity of Chrome Tanning Liquors
• Effective Date: 01-Dec-2023

Overview

ASTM D3898-93(2023), titled Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors, is an internationally recognized standard developed by ASTM International. This standard provides a reliable test method for determining the concentration of chromic oxide in basic chromium tanning liquors-essential chemicals in the leather tanning industry. This method is critical for quality control in manufacturing and helps ensure compliance with purchase specifications for chrome tanning liquors.

The standard covers the analysis of tanning liquors, whether simple or containing additives such as aluminum, zirconium, or other typical masking agents. It is specifically important for determining the correct chromium content to achieve the desired level of leather tannage, supporting efficiency and quality across the leather supply chain.

Key Topics

• Chromic Oxide Determination: The standard outlines a procedure to accurately determine chromic oxide content in tanning liquors, ensuring appropriate levels for effective leather tanning.
• Applicability: The test method is suitable for basic chromium tanning liquors with added metals or complexing agents, accommodating the range of chemical compositions seen in commercial practice.
• Quality Control Monitoring: Provides a reliable approach for manufacturers and purchasers to assess product conformity and make informed decisions regarding chemical purchases and usage.
• Technical Procedure: The outlined technique involves oxidation with sodium peroxide, conversion to chromate, iodine liberation, and titration with standardized sodium thiosulfate.
• Precision and Bias: The method demonstrates high repeatability and reproducibility, with data supporting its accuracy for routine use in laboratories.
• Safety Practices: Users are responsible for adopting appropriate safety, health, and environmental protocols, as safety is not fully addressed within the standard.
• International Recognition: Developed in alignment with World Trade Organization Technical Barriers to Trade (TBT) Committee principles, supporting its global validity.

Applications

• Leather Manufacturing: Ensures accurate dosing of chrome tanning agents, resulting in consistent leather quality and optimized resource utilization.
• Purchasing Specifications: Assists buyers and suppliers in verifying that chromium content meets contractual or regulatory requirements.
• Process Optimization: Provides data to help manufacturers adjust tanning formulations for different leather types and desired properties.
• Quality Assurance Laboratories: Used by chemical analysts for routine monitoring and verification of chrome tanning liquor batches.
• Compliance and Auditing: Supports traceability and documentation in quality audits, as well as compliance with international standards and trade requirements.

Related Standards

• ASTM D2807: Test Method for Chromic Oxide in Leather (Perchloric Acid Oxidation) - referenced as an alternative analytical method if interferences occur during sodium thiosulfate titration.
• ACS Reagent Chemicals: Guidelines for reagent purity, ensuring accuracy and consistency in chemical testing.
• ISO and Other Leather Chemical Standards: ASTM D3898 can be used alongside other international standards regulating chrome, metals, and tanning agent content in leather production.

By following ASTM D3898-93(2023), stakeholders ensure precise measurement of chromic oxide in chromium tanning liquors, facilitating quality leather production and supporting compliance with industry standards throughout global supply chains.

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: D3898 − 93 (Reapproved 2023)
Standard Test Method for
Chromic Oxide in Basic Chromium Tanning Liquors
This standard is issued under the fixed designation D3898; 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 test method covers the determination of chromic 4.1 The procedure described is for the quality control for
oxide in chrome tanning liquors, either simple, with added manufacturing liquors and specifications for the purchase of
aluminum or zirconium, or with the usual masking complexing such liquors.
agents.
4.2 The chromium content of the liquors determines the
1.2 The values stated in SI units are to be regarded as amount to be used to obtain the desired degree of tannage, and
standard. No other units of measurement are included in this hence may be a matter for specification in the purchase of
standard. leather.
1.3 This standard does not purport to address all of the
5. Interferences
safety concerns, if any, associated with its use. It is the
5.1 The test method is generally the most accurate and
responsibility of the user of this standard to establish appro-
convenient for the purpose. However, if the liquor contains
priate safety, health, and environmental practices and deter-
iron or copper, which interfere with the sodium thiosulfate
mine the applicability of regulatory limitations prior to use.
titration, or complex organic or inorganic reducing agents
1.4 This international standard was developed in accor-
(sodium thiosulfate, for example) which are not oxidized by
dance with internationally recognized principles on standard-
alkaline peroxide but reduce hexavalent chromium on
ization established in the Decision on Principles for the
acidification, an alternate procedure must be used. The per-
Development of International Standards, Guides and Recom-
chloric acid method described in Test Method D2807, using the
mendations issued by the World Trade Organization Technical
ferrous sulfate titration, is suitable, although the results ob-
Barriers to Trade (TBT) Committee.
tained may be one to two percent low.
2. Referenced Documents
6. Reagents and Materials
2.1 ASTM Standards:
6.1 Purity of Reagents—Reagent grade chemicals shall be
D2807 Test Method for Chromic Oxide in Leather (Perchlo-
used in all tests. Unless otherwise indicated, it is intended that
ric Acid Oxidation)
all reagents shall conform to the specifications of the Commit-
tee on Analytical Reagents of The American Chemical Society,
3. Summary of Test Method
where such specifications are available. Other grades may be
3.1 The solution is oxidized with sodium peroxide until the
used, provided it is first ascertained that the reagent is of
chromium is completely converted to the chromate ion. The
sufficiently high purity to permit its use without lessening the
solution is boiled to complete oxidation of organic materials
accuracy of the determination.
and to destroy excess peroxide; it is then cooled and acidified.
6.2 Purity of Water—Unless otherwise indicated, reference
Potassium iodide is added and the liberated iodine is titrated
to water shall be understood to mean distilled water or water of
with standardized sodium thiosulfate.
equal purity.
6.3 Sodium Peroxide, (Na O ). Store in original metal can.
2 2
This test method is under the jurisdiction of ASTM Committee D31 on Leather
6.4 Starch Indicator, 1 % —Make a paste of 1 g of soluble
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis This
starch in about 10 mL of water, add 90 mL water and boil for
test method was developed in cooperation with the American Leather Chemists
Assoc.
Current edition approved Dec. 1, 2023. Published December 2023. Originally
approved in 1991. Last previous edition approved in 2015 as D3898 – 93 (2015). ACS Reagent Chemicals, Specifications and Procedures for Reagents and
DOI: 10.1520/D3898-93R23. Standard-Grade Reference Materials, American Chemical Society, Washington,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or DC. For suggestions on the testing of reagents not listed by the American Chemical
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Standards volume information, refer to the standard’s Document Summary page on U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
the ASTM website. copeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3898 − 93 (2023)
1 min with stirring. Cool and add 1 drop of chloroform. The for 5 min. Titrate with 0.1 N sodium thiosulfate standardized as
solution is subject to decomposition and should be renewed if described in 6.4.1. Wh
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