ASTM D6714-01(2006)
(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 D 6716.
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 .
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D6714–01(Reapproved 2006)
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.
1. Scope 4. Summary of Test Method
1.1 This test method covers the determination of chromic 4.1 The perchloric acid method may be applied to the ash
oxide in wet blue that has been partly or completely tanned obtained in Test Method D6716. The resultant ash is dissolved
with chromium compounds. In general the samples will con- into acidic solution in a blend of nitric acid and a prepared
tain chromium content between 1 and 5 %, calculated as oxidation mixture consisting of sulfuric and perchloric acids.
chromic oxide expressed upon a dry basis otherwise referred to Once completed, oxidation of all trivalent to hexavalent
as moisture-free basis (mfb). chromiumisexecutedbycontrolledheating.Upondilution,the
1.2 This test method is specific in that it applies to a sample chromium is indirectly (back) titrated volumetrically with
or samples that are the resultant ash following the execution of standardizedthiosulfateusingreleasediodineasthetitrate.The
Test Method D6716. perchloric acid method requires less manipulation than proce-
1.3 This standard does not purport to address all of the dures based on fusion of the ash. However care must be taken
safety concerns, if any, associated with its use. It is the because of potential hazards in the use of perchloric acid. The
responsibility of the user of this standard to establish appro- perchloric acid method also tends to give low results.
priate safety and health practices and determine the applica-
5. Significance and Use
bilityofregulatorylimitationspriortouse.Specifichazardsare
given in Section 8. 5.1 The procedure described is specific for chromium in wet
blue. Vanadium is the only common interfering element and
2. Referenced Documents
this is rarely present in quantity. The precision and accuracy of
2.1 ASTM Standards: the methods are usually at least as good as the sampling of the
D6658 Test Method for Volatile Matter (Moisture) of Wet wet blue itself, and the accuracy of previously performed test
Blue by Oven Drying methods.
D6659 Practice for Sampling and Preparation of Wet Blue 5.2 The chromium content of wet blue is related to the
for Physical and Chemical Tests degree of tannage obtained, and hence may be a matter for
D6716 Test Method forTotalAsh inWet Blue orWetWhite specification in the purchase of wet blue. The procedure
E180 Practice for Determining the Precision of ASTM described provides adequate accuracy for this purpose.
Methods for Analysis and Testing of Industrial and Spe-
6. Apparatus
cialty Chemicals
6.1 Analytical Balance, accurate and calibrated to 0.001 g.
3. Terminology
6.2 Erlenmeyer Flasks, 250 mL capacity or equivalent.
3.1 Definitions—Thetermsanddefinitionsemployedwithin 6.3 Burette, 50 mL capacity of suitable calibration grade,
this test method are commonly used in normal laboratory minimum calibration of 0.1 mL.
practice and require no special comment. 6.4 Glass Anti-bumping Beads, or equivalent.
6.5 Measuring Cylinders, 50 mL capacity or equivalent.
6.6 Small Glass Filter Funnel.
This test method is under the jurisdiction ofASTM Committee D31 on Leather
6.7 Dessicator, of suitable size and design and charged with
and is the direct responsibility of Subcommittee D31.02 on Blue Stock.
fresh dessicant.
Current edition approved Oct. 1, 2006. Published November 2006. Originally
approved in 2001. Last previous edition approved in 2001 as D6714 - 01. DOI:
6.8 Weighing Vessels, of suitable size and design.
10.1520/D6714-01R06.
6.9 Drying Oven, with accurate variable temperature con-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
trols.
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 6.10 Hot Plate, with accurate variable temperature controls.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6714–01 (2006)
7. Reagents the flask, and allow to stand 5 min in the dark. Titrate with the
thiosulfate solution to be standardized. When the color of the
7.1 Purity of Reagents—Analytical Reagent (AR) grade
solutionhasfadedtoabrownish-green,add2mLof2 %starch
chemicals shall be used in all tests. Unless otherwise indicated,
solutionandcontinuetitratinguntilthedeepbluecolorchanges
it is intended that all reagents shall conform to specifications of
toacleargreen.Recordthetitration.Calculatethenormalityof
theCommitteeonAnalyticalReagentsoftheAmericanChemi-
the thiosulfate solution as follows:
cal Society, where such specifications are available. Other
grades may be used, provided it is first ascertained that the Normality 5 A 4 0.04903 3 B
~ !
reagent is of sufficiently high purity to permit its use without
where:
lessening the accuracy of the determination.
A =K Cr O used, g, and
2 2 7
7.2 Purity of Water—Unless otherwise indicated, reference
B = amount required for titration, mL.
to water shall be understood to mean distilled water or water of
7.16.2 Shelf Life—The thiosulfate solution is relatively
equal purity.
stable. However, it should be restandardized at least once a
7.3 Commercial Reagents—The use of commercially avail-
month.
able pre-standardized analytical reagents and solutions is
7.17 Alternatively, a commercially available pre-
appropriate, providing those reagents and solutions have been
standardized sodium thiosulfate analytical solution may be
prepared in accordance with and conforming to the previously
substituted.
mentioned specifications (see 7.1).
7.4 Nitric Acid—(HNO ), 70 % w/w.
8. Hazards
7.5 Perchloric Acid—(HClO ), 60 to 62 % w/w. 70 or 72 %
8.1 Chemicals used can be harmful, or explosive, or both.
w/w perchloric acid may be substituted, however, storage is
8.2 The improper use of perchloric acid can lead to violent
somewhat more hazardous.
and serious explosions. In general, these can be traced to
7.6 Sulfuric Acid—(H SO ), 96 to 98 % w/w.
2 4
situations where concentrated perchloric acid has come in
7.7 Potassium Iodide—(KI), 99 to 100 % purity.
contact with organic or easily oxidized materials.
7.8 Potassium Iodide Solution—(KI) 10 % w/w. Dissolve
8.3 The exact procedures given must be followed and the
10g(60.1 g) of potassium iodide into 100 mL of water.
digestion, once started, should be kept from possible contact
7.9 Starch Indicator Solution—2 % or equivalent, prepared
with other organic matter. The digestion should never be
according to accepted procedures available in analytical hand-
allowed to boil dry. The perchloric acid should never be used
books.
without accompanying use of nitric and sulfuric acids.
7.10 Oxidizing Mixture—Mix 1666 mL of concentrated
8.4 All spills involving perchloric acid should be flushed
sulfuric acid into an appropriate glass container that contains
with water and a liquid acid neutralizer. Rags, sawdust, and
2500 mL of perchloric acid, using extreme caution while
other organic materials should never be used to mop up spilled
adding. Cool the mixture to room temperature before use.
acid.
7.11 Phosphoric Acid—(H PO ), 40 % v/v. Dilute 45 mLof
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.