ASTM D3873-95
(Test Method)Standard Test Method for Valency State of the Arsenic Component of Ammoniacal Copper Arsenate Solutions
Standard Test Method for Valency State of the Arsenic Component of Ammoniacal Copper Arsenate Solutions
SCOPE
1.1 This test method is intended for testing batches of concentrated ammoniacal copper zinc arsenate (ACZA) solution, prepared by air-oxidation of trivalent arsenic. The test method provides a means of confirming that oxidation has been completed and that at least 99.5 % of the arsenic has been oxidized. The sample for testing should contain 100 ± 20 mg of potential As2 O5. A200-mL aliquot of a concentrate containing 8 to 12 % of preservative oxides is suitable.
1.2 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: D 3873 – 95 An American National Standard
Standard Test Method for
Valency State of the Arsenic Component of Ammoniacal
Copper Arsenate Solutions
This standard is issued under the fixed designation D 3873; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope tee on Analytical Reagents of the American Chemical Society,
where such specifications are available. Other grades may be
1.1 This test method is intended for testing batches of
used, provided it is first ascertained that the reagent is of
concentrated ammoniacal copper ammoniacal copper zinc
sufficiently high purity to permit its use without lessening the
arsenate (ACA/ACZA) solution, prepared by air-oxidation of
accuracy of the determination.
trivalent arsenic. The method provides a means of confirming
5.2 Purity of Water—Unless otherwise indicated, references
that oxidation has been completed and that at least 99.5 % of
to water shall be understood to mean reagent water as defined
the arsenic has been oxidized. The sample for testing should
in Specification D 1193.
contain 100 6 20 mg of potential As O . A200-mL aliquot of
2 5
5.3 Iodine Solution—Add 6.3 and 6.4 g of resublimed
a concentrate containing 8 to 12 % of preservative oxides is
iodine to a 500-mL standard flask. Add 10 to 12 g of potassium
suitable.
iodide and not more than about 20 mL of water. Swirl the
1.2 This standard does not purport to address all of the
contents of the flask at room temperature until all the iodine has
safety concerns, if any, associated with its use. It is the
dissolved, and dilute to the graduation mark. This solution can
responsibility of the user of this standard to establish appro-
be kept for a few weeks if stored in a tight-sealed, glass-
priate safety and health practices and determine the applica-
stoppered, dark bottle in a cool place.
bility of regulatory limitations prior to use.
5.4 Sodium Bicarbonate Solution, Saturated—Add 45 g of
2. Referenced Documents
sodium bicarbonate to 400 mL of water, and swirl occasionally
until most of the sodium bicarbonate goes into solution. Do not
2.1 ASTM Standards:
use heat to dissolve the salt. This solution can be kept in a
D 1193 Specification for Reagent Water
stoppered flask.
3. Summary of Test Method
5.5 Starch Indicator Solution—Make a paste of about 1.0 g
of soluble starch in 5 mL of water. Pour the paste into 200 mL
3.1 Twenty millilitres of tartaric acid solution is added to a
of water, near the boiling point, and then boil for 1 min. When
250 mL Erlenmeyer flask, then 2 mL of the (ACA/ACZA)
the solution has cooled, add a few drops of chloroform as a
concentrate is added. The resulting solution should be light
preservative and keep in a stoppered bottle. Some batches of
blue-green. Next, 20 mL of sodium bicarbonate solution is
starch will not dissolve properly. If the solution separates into
added. The solution will then be light blue. 2 ml of the starch
two layers, use the clear, top layer. If the whole solution is
indicator is added next. To this solution one drop of iodine
cloudy, prepare a fresh solution, or obtain a different supply of
solution from a buret is added. If the solution turns a dark blue
starch.
and remains, it means the aeration has been completed.
5.6 Tartaric Acid Solution—Dissolve 27 g of tartaric acid in
4. Significance and Use
400 mL of water.
4.1 This method tests the completion of aeration which is
6. Procedure
used to convert trivalent arsenic to pentavalent arsenic.
6.1 Take a sample of the (AC
...
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