ASTM D6019-10
(Test Method)Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
Test Method for Determination of Chromic Oxide in Basic Chromium Tanning Liquors (Ammonium Persulfate Oxidation)
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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Designation: D6019 − 10
TestMethod for
Determination of Chromic Oxide in Basic Chromium
1
Tanning Liquors (Ammonium Persulfate Oxidation)
This standard is issued under the fixed designation D6019; 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 tee onAnalytical Reagents ofTheAmerican Chemical Society,
2
where such specifications are available. Other grades may be
1.1 This test method covers the determination of chromic
used, provided it is first ascertained that the reagent is of
oxide in chrome tanning liquors, either simple, with added
sufficiently high purity to permit its use without lessening the
aluminum or zirconium, or with the usual masking complexing
accuracy of the determination.
agents.
4.2 Purity of Water—Unless otherwise indicated, reference
1.2 The values stated in SI units are to be regarded as
to water shall be understood to mean distilled water or water of
standard. No other units of measurement are included in this
equal purity.
standard.
4.3 Ammonium Persulfate—20 % solution 100 gm of per-
1.3 This standard does not purport to address all of the
sulfate into 500 mL water.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4.4 Starch Indicator,1%—Make a paste of1gof soluble
priate safety and health practices and determine the applica-
starch in about 10 mL of water, add 90 mL water, and boil for
bility of regulatory limitations prior to use.
1 min with stirring. Cool and add one drop of chloroform. The
solution is subject to decomposition and should be renewed if
2. Summary of Test Method
a deep blue color is not obtained on addition of one drop of
2.1 The solution is oxidized with ammonium persulfate indicator to a solution of 1 drop tincture of iodine in 100 mL
until the chromium is completely converted to the chromate
of water.
ion. The solution is boiled to complete oxidation of organic
4.5 Sodium Thiosulfate Solution, 0.1 N—Dissolve 24.85 g
materialsandtodestroyexcessammoniumpersulfate;itisthen
of Na S O ·5H O in water, add1gNa CO , and dilute to 1 L.
2 2 3 2 2 3
cooled and acidified. Potassium iodide is added, and the
4.5.1 Standardization—Dry potassium dichromate
liberated iodine is titrated with standardized sodium thiosul-
(K Cr O ) in an oven at 130°C for 2 h and cool in a desiccator.
2 2 7
fate.
Weigh into a glass stoppered Erlenmeyer flask (500 mL) about
0.2 g of potassium dichromate to an accuracy of 0.1 mg.
3. Significance and Use
Dissolvein250mLwater,add15mL1:4hydrochloricacid,20
3.1 The procedure described is for the quality control for
mL of 10 % potassium iodide solution, stopper the flask, and
manufacturing liquors and specifications for the purchase of
allow to stand 5 min in the dark. Titrate with the sodium
such liquors.
thiosulfate to be standardized. When the color of the solution
3.2 The chromium content of the liquors determines the has faded to a brownish-green, add 2 mL of 1 % starch
amount to be used to obtain the desired degree of tannage, and solution, and continue titrating until the deep blue color
hence may be a matter for specification in the purchase of changes to a clear green. Record the titration.
leather.
weight potassium dichromate
normality of sodium thiosulfate 5 (1)
0.04903 3mL titration
4. Reagents and Materials
The thiosulfate solution is quite stable but should be restan-
4.1 Purity of Reagents—Reagent grade chemicals shall be
dardized at least once a month.
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
2
Reagent Chemicals, American Chemical Society Specifications , American
1
This test method is under the jurisdiction ofASTM Committee D31 on Leather Chemical Society, Washington, DC. For suggestions on the testing of reagents not
and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis. listed by the American Chemical Society, see Analar Standards for Laboratory
Current edition approved Oct. 1, 2010. Published October 2010. Originally Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
approved in 1996. Last previous edition approved in 2006 as D6019 - 96(2006). and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
DOI: 10.1520/D6019-10. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6019 − 10
4.6 Potassium Dichromate, K Cr O , primary standard 6. Calculation
2 2 7
grade.
6.1 Cal
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:D6019–96 (Reapproved 2006) Designation:D6019–10
Test Method for
Determination of Chromic Oxide in Basic Chromium
1
Tanning Liquors (Ammonium Persulfate Oxidation)
This standard is issued under the fixed designation D6019; 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
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.
1.2The values stated in SI units are to be regarded as the standard.
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.
2. Summary of Test Method
2.1 The solution is oxidized with ammonium persulfate until the chromium is completely converted to the chromate ion. The
solution is boiled to complete oxidation of organic materials and to destroy excess ammonium persulfate; it is then cooled and
acidified. Potassium iodide is added, and the liberated iodine is titrated with standardized sodium thiosulfate.
3. Significance and Use
3.1 The procedure described is for the quality control for manufacturing liquors and specifications for the purchase of such
liquors.
3.2 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.
4. Reagents and Materials
4.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of The American Chemical Society, where
2
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
4.2 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean distilled water or water of
equal purity.
4.3 Ammonium Persulfate—20 % solution 100 gm of persulfate into 500 mL water.
4.4 Starch Indicator, 1 %—Make a paste of1gof soluble starch in about 10 mLof water, add 90 mLwater, and boil for 1 min
with stirring. Cool and add one drop of chloroform. The solution is subject to decomposition and should be renewed if a deep blue
color is not obtained on addition of one drop of indicator to a solution of 1 drop tincture of iodine in 100 mL of water.
4.5 Sodium Thiosulfate Solution, 0.1 N—Dissolve 24.85 g of Na S O ·5H O in water, add1gNa CO , and dilute to 1 L.
2 2 3 2 2 3
4.5.1 Standardization—Dry potassium dichromate (K Cr O ) in an oven at 130°C for 2 h and cool in a desiccator. Weigh into
2 2 7
a glass stoppered Erlenmeyer flask (500 mL) about 0.2 g of potassium dichromate to an accuracy of 0.1 mg. Dissolve in 250 mL
water, add 15 mL 1:4 hydrochloric acid, 20 mL of 10 % potassium iodide solution, stopper the flask, and allow to stand 5 min in
the dark. Titrate with the sodium thiosulfate to be standardized. When the color of the solution has faded to a brownish-green, add
2 mL of 1 % starch solution, and continue titrating until the deep blue color changes to a clear green. Record the titration.
1
This test method is under the jurisdiction of ASTM Committee D31 on Leather and is the direct responsibility of Subcommittee D31.06 on Chemical Analysis.
Current edition approved Oct. 1, 2006.2010. Published November 2006.October 2010. Originally approved in 1996. Last previous edition approved in 20012006 as
D6019 - 96(20016). DOI: 10.1520/D6019-96R06.10.1520/D6019-10.
2
Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
Copyright © AS
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