ASTM D1845-86(1999)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D 1845 – 86 (Reapproved 1999)
Standard Test Methods for
Chemical Analysis of Strontium Chromate Pigment
This standard is issued under the fixed designation D 1845; 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 4. Apparatus
1.1 These test methods cover the chemical analysis of 4.1 Gooch crucible.
strontium chromate pigment. 4.2 Electric Furnace, capable of 800°C.
1.2 The analytical procedures appear in the following order:
5. Purity of Reagents
Sections
5.1 Reagent grade chemicals shall be used in all tests.
Strontium by the Strontium Sulfate Method 7to10
Unless otherwise indicated, it is intended that all reagents shall
Chromium by the Thiosulfate Method 11to14
conform to the specifications of the Committee on Analytical
Chloride Content 15
Sulfate Content 16
Reagents of the American Chemical Society, where such
Moisture and Other Volatile Matter 17
specifications are available. Other grades may be used, pro-
Coarse Particles 18
vided it is first ascertained that the reagent is of sufficiently
Mass Color and Tinting Strength 19
high purity to permit its use, without lessening the accuracy of
1.3 This standard does not purport to address the safety
the determination.
concerns associated with its use. It is the responsibility of the
5.2 Unless otherwise indicated, references to water shall be
user of this standard to establish appropriate safety and health
understood to mean Type II of Specification D 1193.
practices and determine the applicability of regulatory limita-
tions prior to use.
6. Preparation of Sample
6.1 Mix the sample thoroughly. Take a sufficient quantity
2. Referenced Documents
for chemical analysis and pass it through a No. 325 (4-μm)
2.1 ASTM Standards:
sieve.
D 185 Test Methods for Coarse Particles in Pigments,
Pastes, and Paints
STRONTIUM BY THE STRONTIUM SULFATE
D 280 Test Methods for Hygroscopic Moisture (and Other
METHOD
Matter Volatile Under the Test Conditions) in Pigments
7. Reagents
D 387 Test Method for Color and Strength of Color Pig-
ments with a Mechanical Muller
7.1 Acetic Acid (glacial).
D 444 Test Methods for Chemical Analysis of Zinc Yellow
7.2 Ammonium Hydroxide (1+3)—Mix 1 volume of concen-
Pigment (Zinc Chromate Yellow)
trated ammonium hydroxide (NH OH, sp gr 0.90) with 3
D 1193 Specification for Reagent Water
volumes of water.
7.3 Ethyl Alcohol, conforming to Formula No. 2B or No. 30
3. Significance and Use
of the U.S. Bureau of Alcohol, Tobacco, and Firearms.
3.1 These test methods may be used to confirm the stated
7.4 Hydrochloric Acid (1+1)—Mix equal volumes of con-
strontium oxide and chromium oxide content of strontium
centrated hydrochloric acid (HCl, sp gr 1.19) and water.
chromate.
7.5 Sulfuric Acid (1+19)—Mix 1 volume of concentrated
sulfuric acid (H SO , sp gr 1.84) with 19 volumes of water.
2 4
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and are under the jurisdiction of
Subcommittee D01.31 on Pigment Specifications. Reagent Chemicals, American Chemical Society Specifications, American
Current edition approved April 25, 1986. Published June 1986. Originally Chemical Society, Washington, DC. For suggestions on the testing of reagents not
e2
published as D 1845 – 61 T. Last previous edition D 1845– 65 (1979) . listed by the American Chemical Society, see Analar Standards for Laboratory
Annual Book of ASTM Standards, Vol 06.03. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 06.01. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 11.01. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 1845
8. Procedure 1.19). Titrate the liberated iodine with sodium thiosulfate
solution until the reddish-brown color becomes quite faint. Add
8.1 Weigh to 0.1 mg about 0.5 g of the sample into a
5 mL of starch solution and continue the titration dropwise
400-mL beaker. Add 40 mL of HCl (1+1) and heat the solution
until the blue color changes to a pale green. Calculate the
to dissolve the pigment. Add 40 mL of ethyl alcohol until the
normality of the sodium thiosulfate solution as follows:
chromium is reduced, as this is indicated by a dark coloration
of the solution. Add to the solution 100 mL of water and 2.5000
N 5
M
sufficient NH OH (1+3) to form a slight persistent precipitate.
8.2 Add HCl dropwise until the precipitate just redissolves
where:
(Note 1). Heat the solution to just under boiling and add 20 mL
N 5 normality, and
of H SO (1+19). Add 100 mL of ethyl alcohol and allow the
2 4
M 5 sodium thiosulfate solution, g.
precipitate to settle for several hours or overnight.
11.4 Starch Indicator Solution—Make a homogenous paste
NOTE 1—For a cleaner precipitate, add HCl until a pH of 2.0 is reached, of 10 g of soluble starch in cold water. Add to this 1 L of
instead of adding HCl dropwise until the precipitate is just dissolved. Then
boiling water, stir rapidly, and cool. Salicylic acid (1.25 g/L)
add 2
...