ASTM D3898-93(2009)
(Test Method)Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
Standard Test Method for Chromic Oxide in Basic Chromium Tanning Liquors
SIGNIFICANCE AND USE
The procedure described is for the quality control for manufacturing liquors and specifications for the purchase of such liquors.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D3898 − 93(Reapproved 2009)
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 4.2 The chromium content of the liquors determines the
amount to be used to obtain the desired degree of tannage, and
1.1 This test method covers the determination of chromic
hence may be a matter for specification in the purchase of
oxide in chrome tanning liquors, either simple, with added
leather.
aluminum or zirconium, or with the usual masking complexing
agents.
5. Interferences
1.2 The values stated in SI units are to be regarded as
5.1 The test method is generally the most accurate and
standard. No other units of measurement are included in this
convenient for the purpose. However, if the liquor contains
standard.
iron or copper, which interfere with the sodium thiosulfate
1.3 This standard does not purport to address all of the
titration, or complex organic or inorganic reducing agents
safety concerns, if any, associated with its use. It is the
(sodium thiosulfate, for example) which are not oxidized by
responsibility of the user of this standard to establish appro-
alkaline peroxide but reduce hexavalent chromium on
priate safety and health practices and determine the applica-
acidification, an alternate procedure must be used. The per-
bility of regulatory limitations prior to use.
chloricacidmethoddescribedinTestMethodD2807,usingthe
ferrous sulfate titration, is suitable, although the results ob-
2. Referenced Documents
tained may be one to two percent low.
2.1 ASTM Standards:
6. Reagents and Materials
D2807 Test Method for Chromic Oxide in Leather (Perchlo-
6.1 Purity of Reagents—Reagent grade chemicals shall be
ric Acid Oxidation)
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
3. Summary of Test Method
tee onAnalytical Reagents ofTheAmerican Chemical Society,
3.1 The solution is oxidized with sodium peroxide until the 3
where such specifications are available. Other grades may be
chromium is completely converted to the chromate ion. The
used, provided it is first ascertained that the reagent is of
solution is boiled to complete oxidation of organic materials
sufficiently high purity to permit its use without lessening the
and to destroy excess peroxide; it is then cooled and acidified.
accuracy of the determination.
Potassium iodide is added and the liberated iodine is titrated
6.2 Purity of Water—Unless otherwise indicated, reference
with standardized sodium thiosulfate.
to water shall be understood to mean distilled water or water of
equal purity.
4. Significance and Use
6.3 Sodium Peroxide, (Na O ). Store in original metal can.
2 2
4.1 The procedure described is for the quality control for
manufacturing liquors and specifications for the purchase of 6.4 Starch Indicator,1%—Make a paste of1gof soluble
such liquors. starch in about 10 mL of water, add 90 mL water and boil for
1 min with stirring. Cool and add 1 drop of chloroform. The
solution is subject to decomposition and should be renewed if
a deep blue color is not obtained on addition of 1 drop of
This test method is under the jurisdiction ofASTM Committee D31 on Leather
indicator to a solution of 1 drop tincture of iodine in 100 mL
and is the direct responsibility of Subcommittee D31.06 on ChemicalAnalysis This
test method was developed in cooperation with the American Leather Chemists
of water.
Assoc.
Current edition approved April 1, 2009. Published July 2009. Originally
approved in 1991. Last previous edition approved in 2003 as D3898 – 93 (2003). Reagent Chemicals, American Chemical Society Specifications , American
DOI: 10.1520/D3898-93R09. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
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.
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D3898 − 93 (2009)
6.5 Sodium Thiosulfate Solution, 0.1 N—Dissolve 24.85 g continue the titration until the deep blue color changes to a
of Na S O ·5 H O
...
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