ASTM D6714-01(2010)e1
(Test Method)Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
Standard Test Method for Chromic Oxide in Ashed Wet Blue (Perchloric Acid Oxidation)
SIGNIFICANCE AND USE
The procedure described is specific for chromium in wet blue. Vanadium is the only common interfering element and this is rarely present in quantity. The precision and accuracy of the methods are usually at least as good as the sampling of the wet blue itself, and the accuracy of previously performed test methods.
The chromium content of wet blue is related to the degree of tannage obtained, and hence may be a matter for specification in the purchase of wet blue. The procedure described provides adequate accuracy for this purpose.
SCOPE
1.1 This test method covers the determination of chromic oxide in wet blue that has been partly or completely tanned with chromium compounds. In general the samples will contain chromium content between 1 and 5 %, calculated as chromic oxide expressed upon a dry basis otherwise referred to as moisture-free basis (mfb).
1.2 This test method is specific in that it applies to a sample or samples that are the resultant ash following the execution of Test Method D6716.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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. Specific hazards are given in Section 8.
General Information
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D6714 − 01 (Reapproved2010)
Standard Test Method for
Chromic Oxide in Ashed Wet Blue (Perchloric Acid
Oxidation)
This standard is issued under the fixed designation D6714; 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.
´ NOTE—The SI statement was added and the Subcommittee name in footnote 1 was corrected editorially in November
2010.
1. Scope cialty Chemicals (Withdrawn 2009)
1.1 This test method covers the determination of chromic
3. Terminology
oxide in wet blue that has been partly or completely tanned
3.1 Definitions—The terms and definitions employed within
with chromium compounds. In general the samples will con-
this test method are commonly used in normal laboratory
tain chromium content between 1 and 5 %, calculated as
practice and require no special comment.
chromic oxide expressed upon a dry basis otherwise referred to
as moisture-free basis (mfb).
4. Summary of Test Method
1.2 This test method is specific in that it applies to a sample
4.1 The perchloric acid method may be applied to the ash
or samples that are the resultant ash following the execution of
obtained in Test Method D6716. The resultant ash is dissolved
Test Method D6716.
into acidic solution in a blend of nitric acid and a prepared
1.3 The values stated in SI units are to be regarded as
oxidation mixture consisting of sulfuric and perchloric acids.
standard. No other units of measurement are included in this
Once completed, oxidation of all trivalent to hexavalent
standard.
chromiumisexecutedbycontrolledheating.Upondilution,the
chromium is indirectly (back) titrated volumetrically with
1.4 This standard does not purport to address all of the
standardizedthiosulfateusingreleasediodineasthetitrate.The
safety concerns, if any, associated with its use. It is the
perchloric acid method requires less manipulation than proce-
responsibility of the user of this standard to establish appro-
dures based on fusion of the ash. However care must be taken
priate safety and health practices and determine the applica-
because of potential hazards in the use of perchloric acid. The
bilityofregulatorylimitationspriortouse.Specifichazardsare
perchloric acid method also tends to give low results.
given in Section 8.
5. Significance and Use
2. Referenced Documents
5.1 The procedure described is specific for chromium in wet
2.1 ASTM Standards:
blue. Vanadium is the only common interfering element and
D6658 Test Method for Volatile Matter (Moisture) of Wet
this is rarely present in quantity. The precision and accuracy of
Blue by Oven Drying
the methods are usually at least as good as the sampling of the
D6659 Practice for Sampling and Preparation of Wet Blue
wet blue itself, and the accuracy of previously performed test
for Physical and Chemical Tests
methods.
D6716 Test Method for TotalAsh in Wet Blue or Wet White
5.2 The chromium content of wet blue is related to the
E180 Practice for Determining the Precision of ASTM
degree of tannage obtained, and hence may be a matter for
Methods for Analysis and Testing of Industrial and Spe-
specification in the purchase of wet blue. The procedure
described provides adequate accuracy for this purpose.
This test method is under the jurisdiction ofASTM Committee D31 on Leather
6. Apparatus
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
Current edition approved Oct. 1, 2010. Published November 2010. Originally
6.1 Analytical Balance, accurate and calibrated to 0.001 g.
approved in 2001. Last previous edition approved in 2006 as D6714 - 01 (2006).
6.2 Erlenmeyer Flasks, 250 mL capacity or equivalent.
DOI: 10.1520/D6714-01R10E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6714 − 01 (2010)
6.3 Burette, 50 mL capacity of suitable calibration grade, 7.12 Hydrochloric Acid—(HCl), 1:1 dilution of 37 % HCl
minimum calibration of 0.1 mL. w/w. Used in standardization of thiosulfate solution.
6.4 Glass Anti-bumping Beads, or equivalent. 7.13 Potassium Dichromate—(K Cr O ). Used in standard-
2 2 7
ization of thiosulfate solution.
6.5 Measuring Cylinders, 50 mL capacity or equivalent.
7.14 Sodium Carbonate—(Na CO ). Used in preparation of
2 3
6.6 Small Glass Filter Funnel.
thiosulfate solution.
6.7 Dessicator, of suitable size and design and charged with
7.15 Sodium Thiosulfate—(Na S O ·5H O). Used to pre-
2 2 3 2
fresh dessicant.
pare thiosulfate solution.
6.8 Weighing Vessels, of suitable size and design.
7.16 Sodium Thiosulfate Standard Solution—(Na S O ),
2 2 3
6.9 Drying Oven, with accurate variable temperature con-
0.1N (60.0002). Dissolve 24.85 g of sodium thiosulfate
trols.
(Na S O ·5H O) in previously boiled water, add 1.00 g of
2 2 3 2
6.10 Hot Plate, with accurate variable temperature controls. sodium carbonate (Na CO ) and dilute to 1000 mL.
2 3
7.16.1 Standardization—Dry potassium dichromate
(K Cr O ) in an oven at 130°C for 2 h and cool in a dessicator.
7. Reagents
2 2 7
Once cool, weigh about 0.2 g (60.0001 g) of this dry
7.1 Purity of Reagents—Analytical Reagent (AR) grade
potassium dichromate into a clean 250 mL, glass-stoppered
chemicals shall be used in all tests. Unless otherwise indicated,
Erlenmeyer flask. Dissolve in 50 mL of water; add 4 mL of
it is intended that all reagents shall conform to specifications of
hydrochloricacid(HCl,1:1)and20mLofKIsolution.Stopper
theCommitteeonAnalyticalReagentsoftheAmericanChemi-
the flask, and allow to stand 5 min in the dark. Titrate with the
cal Society, where such specifications are available. Other
thiosulfate solution to be standardized. When the color of the
grades may be used, provided it is first ascertained that the
solutionhasfadedtoabrownish-green,add2mLof2 %starch
reagent is of sufficiently high purity to permit its use without
solutionandcontinuetitratinguntilthedeepbluecolorchanges
lessening the accuracy of the determination.
toacleargreen.Recordthetitration.Calculatethenormalityof
7.2 Purity of Water—Unless otherwise indicated, reference
the thiosulfate solution as follows:
to water shall be understood to mean distilled water or water of
Normality 5 A÷ 0.04903 3B
~ !
equal purity.
where:
7.3 Commercial Reagents—The use of commercially avail-
A =K Cr O used, g, and
able pre-standardized analytical reagents and solutions is 2 2 7
B = amount required for titration, mL.
appropriate, providing those reagents and solutions have been
prepared in accordance with and conforming to the previously
7.16.2 Shelf Life—The thiosulfate solution is relatively
mentioned specifications (see 7.1).
stable. However, it should be restandardized at least once a
month.
7.4 Nitric Acid—(HNO ), 70 % w/w.
7.17 Alternatively, a commercially available pre-
7.5 Perchloric Acid—(HClO ), 60 to 62 % w/w. 70 or 72 %
standardized sodium thiosulfate analytical solution may be
w/w perchloric acid may be substituted, however, storage is
substituted.
somewhat more hazardous.
7.6 Sulfuric Acid—(H SO ), 96 to 98 % w/w.
2 4
8. Hazards
7.7 Potassium Iodide—(KI), 99 to 100 % purity.
8.1 Chemicals used can be harmful, or explosive, or both.
7.8 PotassiumIodideSolution—(KI)10 %w/w.Dissolve10
8.2 The improper use of perchloric acid can lead to violent
g(60.1 g) of potassium iodide into 100 mL of water.
and serious explosions.
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