ASTM D5356-10

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D5356 − 10
StandardTest Method for
1
pH of Chrome Tanning Solutions
This standard is issued under the fixed designation D5356; 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 standard shall be governing except where the text of this test
method specifically deviates.
1.1 This test method covers the determination of the pH of
chrome tanning solutions.
5. Significance and Use
1.2 The values stated in SI units are to be regarded as
5.1 This test method is designed to measure the pH of a
standard. No other units of measurement are included in this
chrome tanning solution which has been diluted to a specific
standard.
concentration.This is considered to be a measure of the acidity
1.3 This standard does not purport to address all of the
or alkalinity of the solution.
safety concerns, if any, associated with its use. It is the
5.2 This test method is suitable for quality control in the
responsibility of the user of this standard to establish appro-
manufacture of leather.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
6. Apparatus
2. Referenced Documents
6.1 pH Meter, either battery or line-operated equipped with
2
appropriate electrodes. The meter shall have a maximum scale
2.1 ASTM Standards:
division of 0.1 pH unit and reproducibility of 0.05 pH unit.
D3898 Test Method for Chromic Oxide in Basic Chromium
Tanning Liquors
NOTE 1—Sellers list reasonably priced models having more sensitivity
E70 Test Method for pH of Aqueous Solutions With the and greater reproducibility.
Glass Electrode
7. Reagents
3. Terminology
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
3.1 Definitions of Terms Specific to This Standard:
all reagents shall conform to the specifications of the Commit-
3.1.1 pH, of a solution—the negative logarithm of the
tee onAnalytical Reagents of theAmerican Chemical Society,
hydrogen ion activity.
3
where such specifications are available. Other grades may be
3.1.1.1 Discussion—A solution of pH 7 is neutral at 24°C.
used, provided it is first ascertained that the reagent is of
Lower numbers indicate increasing acidity, higher numbers
sufficiently high purity to permit its use without lessening the
indicate increasing alkalinity.
accuracy of the determination.
4. Summary of Test Method
7.2 Purity of Water—Unless otherwise indicated, references
4.1 The chrome tanning liquor is diluted to a concentration to water shall be understood to mean distilled water or water of
equal purity.
of 25.0 6 0.5 g chromic oxide equivalent per litre, allowed to
come to equilibrium and the pH is then measured with the
7.3 Buffer Solutions—Commercially available buffer solu-
appropriate meter. For general details of a procedure, Test
tions of 2.00 6 0.02 pH and 4.00 6 0.02 pH shall be used for
Method E70 should be consulted. The provisions of the
meter standardization, in accordance with the manufacturer’s
recommendations and the provisions set forth in Test Method
E70.
1
This test method is under the jurisdiction ofASTM Committee D31 on Leather
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis
Current edition approved Nov. 1, 2010. Published November 2010. Originally
3
approved in 1993. Last previous edition approved in 2009 as D5356 – 93 (2009). Reagent Chemicals, American Chemical Society Specifications , American
DOI: 10.1520/D5356-10. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D5356 − 10
NOTE 3—If the dilution described in Note 2 takes place essentially at
8. Standardization
room temperature, the change in pH is sufficiently slight that 60-min
8.1 Standardize the meter against the pH 4.00 standard, in
equilibration will suffice. If it is necessary to concentrate the solution by
accordance with the manufacturer’s recommendations and the
boiling, or the or
...