ASTM D444-88(1999)
(Test Method)Standard Test Methods for Chemical Analysis of Zinc Yellow Pigment (Zinc Chromate Yellow)
Standard Test Methods for Chemical Analysis of Zinc Yellow Pigment (Zinc Chromate Yellow)
SCOPE
1.1 These test methods cover procedures for the chemical analysis of the pigment known commercially as "zinc yellow" or "zinc chromate yellow."
1.2 The analytical procedures appear in the following order: Sections Moisture and Other Volatile Matter 7 Combined Water 8 Chromium: Dichromate Method 9 to 11 Thiosulfate Method 9, 12, and 13 Zinc: Hydroxyquinoline Method 9, 14, and 15 Ferrocyanide Method 9, 16, and 17 Alkaline Salts 18 and 19 Sulfates 20 and 21 Chlorides 22 and 23 Matter Insoluble in Dilute Acetic 24 Acid Coarse Particles 25
1.3 This standard does not purport to address all of the safety problems, 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 444 – 88 (Reapproved 1999)
Standard Test Methods for
Chemical Analysis of Zinc Yellow Pigment (Zinc Chromate
Yellow)
This standard is issued under the fixed designation D 444; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E 11 Specification for Wire-Cloth Sieves for Testing Pur-
poses
1.1 These test methods cover procedures for the chemical
E 50 Practices for Apparatus, Reagents, and Safety Precau-
analysis of the pigment known commercially as “zinc yellow”
tions for Chemical Analysis of Metals
or“ zinc chromate yellow.”
1.2 The analytical procedures appear in the following order:
3. Significance and Use
Sections
3.1 This test method has been developed to standardize the
Moisture and Other Volatile Matter 7
Combined Water 8
chemical analysis of zinc chromate yellow pigment and to
Chromium:
provide alternate methods of analysis for chromium and zinc.
Dichromate Method 9-11
Thiosulfate Method 9, 12, and 13
4. Preparation of Sample
Zinc:
Hydroxyquinoline Method 9, 14, and 15
4.1 Mix the laboratory sample thoroughly. Take a sufficient
Ferrocyanide Method 9, 16, and 17
quantity for the chemical analyses and pass it through a
Alkaline Salts 18 and 19
Sulfates 20 and 21
180-μm (No. 80) sieve, grinding in a mortar if necessary.
Chlorides 22 and 23
Matter Insoluble in Dilute Acetic 24
NOTE 1—Detailed requirements for this sieve are given in Specification
Acid
E11.
Coarse Particles 25
5. Reagents
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5.1 Purity of Reagents—Unless otherwise indicated, it is
intended that all reagents shall conform to the specifications of
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- the Committee on Analytical Reagents of the American Chemi-
cal Society, where such specifications are available. Other
bility of regulatory limitations prior to use.
grades may be used, provided it is first ascertained that the
2. Referenced Documents
reagent is of sufficiently high purity to permit its use without
2.1 ASTM Standards: lessening the accuracy of the determination.
D 185 Test Methods for Coarse Particles in Pigments, 5.2 Purity of Water—Unless otherwise indicated, references
Pastes, and Paints to water for use in the preparation of reagents and in analytical
D 280 Test Methods for Hygroscopic Moisture (and Other procedures shall conform to Type II reagent water, in Specifi-
Matter Volatile Under the Test Conditions) in Pigments cation D 1193.
D 478 Specification for Zinc Yellow (Zinc Chromate)
D 1193 Specification for Reagent Water
Annual Book of ASTM Standards, Vol 14.02.
1 5
These test methods are under the jurisdiction of ASTM Committee D-1 on Paint Annual Book of ASTM Standards, Vol 03.05.
and Related Coatings, Materials, and Applications and are the direct responsibility Reagent Chemicals, American Chemical Society Specifications, American
of Subcommittee D 01.31 on Pigment Specifications. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved Oct. 31, 1988. Published December 1988. Originally listed by the American Chemical Society, see Analar Standards for Laboratory
e1
published as D 444 – 37. Last previous edition D 444 – 81(1987) . Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 06.03. 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 444
6. Precision 11. Procedure
6.1 Precision statements have not been established. 11.1 Pipet 50 mL of the solution of the specimen (Section 7)
into a 600-mL beaker. Add 200 to 250 mL of water and 10 mL
MOISTURE AND OTHER VOLATILE MATTER
of H SO (sp gr 1.84). Cool to 35°C or below.
2 4
11.2 Add an excess of ferrous ammonium sulfate solution
7. Procedure
and back-titrate with 0.1 N K Cr O solution, using ortho-
2 2 7
7.1 Determine moisture and other volatile matter in accor-
phenanthroline indicator. Carry out a blank titration of the
dance with Test Method A of Test Method D 280.
same amount of ferrous ammonium sulfate solution at the same
time and in the same manner.
COMBINED WATER
11.3 Calculation—Calculate the percent of chromium C as
CrO , as follows:
8. Procedure
C 5 ~B 2 V !N 3 0.03334/S 3 100
1 1 1 1
8.1 Weigh to 0.1 mg3gofthe oven-dried material from the
determination of moisture and other volatile matter (Note 2 and
where:
Note 3), and place in a porcelain boat. Introduce the boat with
B 5 K Cr O solution required for titration of the
1 2 2 7
the charge into a refractory combustion tube in an electrically-
blank, mL,
heated combustion furnace of the type used for the determina-
V 5 K Cr O solution required for back-titration of
1 2 2 7
tion of carbon in steel by direct combustion (Note 4). Place the
the specimen, mL,
boat at the center of the combustion tube maintained at a
N 5 normality of the K Cr O solution, and
1 2 2 7
temperature of 1000°C for 4 h. Draw a current of pure dry air
S 5 specimen in the aliquot used, g.
or dry nitrogen through the tube to sweep the evolved moisture 0.03334 5 milliequivalents weight of CrO .
into a previously weighed absorption tube containing anhy-
11.4 Alternatively, the solution of the specimen may be
drous magnesium perchlorate (Mg(ClO ) ) or other efficient
titrated directly with the ferrous ammonium sulfate solution,
4 2
desiccant. The weight increase of the absorption tube repre-
using an electrometric titration assembly to detect the end
sents the “combined water.”
point. Standardize the ferrous solution against K Cr O .
2 2 7
NOTE 2—Loss on ignition of the pigment does not suffice for the
CHROMIUM BY THE THIOSULFATE TEST
determination of combined water in zinc yellow.
METHOD
NOTE 3—If the pigment contains an organic treating agent, first remove
this treating agent by washing with ether or chloroform.
12. Reagents
NOTE 4—See Apparatus No. 1 for the determination of total carbon by
direct combustion as described in Practices E 50.
12.1 Potassium Iodide Solution (150 g/L)—Dissolve 150 g
of potassium iodide (KI) in water and dilute to 1 L.
SPECIMEN SOLUTION FOR DETERMINATION OF
12.2 Sodium Thiosulfate, Standard Solution (0.1 N)—
CHROMIUM AND ZINC
Dissolve 24.8 g of sodium thiosulfate of (Na S O ·5H O) in
2 2 3 2
1 L of freshly boiled and cooled water contained in a sterile
9. Procedure
glass bottle. If sulfur precipitates during preparation or upon
9.1 Weigh to 0.1 mg about a 4-g specimen and mix with 50
subsequent use, discard the solution and prepare a new one.
mL of cold sulfuric acid (H SO ) (1+5). It should dissolve
2 4
Standardize against iodine.
completely at this stage (Note 5). Dilute the solution to 500 mL
12.3 Starch Indicator Solution—Stir up 2 to3gof potato
in a volumetric flask.
starch with 100 mL salicylic acid solution (1 %), and boil the
NOTE 5—A cloudy solution may result if the pigment contains a
mixture until the starch is practically dissolved, then dilute to
surface-treating agent. In this case, it usually can be cleared by cooling in
1 L with water.
an ice-bath and filtering through a medium porosity fritted disk. If the
solution is not clarified by this treatment, extract a portion of the original
13. Procedure
sample with a solvent such as chloroform before the analysis is begun.
13.1 Pipet a 25-mL aliquot of the solution of the specimen
CHROMIUM BY THE DICHROMATE TEST (Section 9) into a 500-mL glass-stoppered Erlenmeyer iodi-
METHOD metric flask or other suitable glass-stoppered bottle containing
200 mL of H SO (1+39). Add 20 mL of KI solution (150 g/L),
2 4
10. Reagents
stopper, and allow the solution to stand for approximately 5
10.1 Ferrous Ammonium Sulfate Solution— Dissolve 80 g min.
of ferrous ammonium sulfate (FeSO · (NH ) SO ·6H O) in 13.2 Titrate the liberated iodine with 0.1 N Na S O solu-
4 4 2 4 2
2 2 3
50 mL of H SO (sp gr 1.84) and enough water to make 1 L of tion at room temperature until the reddish brown iodine color
2 4
solution. Mix thoroughly before use. This solution is approxi- becomes quite faint. Add 5 mL of starch solution and continue
mately 0.2 N. the titration until the final color change becomes pale green
10.2 Ortho-Phenanthroline Indicator Solution—0.5 % in with no blue tinge. Titrate this final titration by swirling the
water. flask at least three times after each addition of the Na S O
2 2 3
10.3 Potassium Dichromate, Standard Solution (0.1 N)— solution, being sure that there is no further color change,
Dissolve 4.9035 g of dried potassium dichromate (K Cr O )in especially at the final stage of the titration. The green end point
2 2 7
water and dilute to 1 L in a volumetric flask. is definite and sharp.
D 444
13.3 Calculation—Calculate the percent of chromium C as of hydrochloric acid (HCl, sp gr 1.19) and 20 mL of water.
CrO as follows: Drop in a small piece of litmus paper, add ammonium
hydroxide (NH OH) until slightly alkaline, then add HCl until
C 5 @~V N 3 0.03334!/S # 3 100
2 2 2
just acid, and then 3 mL more of HCl. Dilute to about 250 mL
where:
with hot water and heat nearly to boiling. Run in the
V 5 Na S O solution required for titration of the speci-
2 2 2 3 K Fe(CN) solution slowly from a buret, while stirring con-
4 6
men, mL
stantly, until a drop tested on a white porcelain plate with a
N 5 normality of the Na S O solution, and
2 2 2 3
drop of the uranyl indicator solution shows a brown tinge after
S 5 specimen in the aliquot used, g.
standing 1 min. Do not allow the temperature of the solution to
fall below 70°C during the titration. Run a blank using the
ZINC BY THE HYDROXYQUINOLINE TEST
same amounts of reagents and water as in the standardization.
METHOD
The standardization must be made under the same conditions
(Suitable if No Interfering Substances Are Present)
of temperature, volume, and acidity as obtained when the
specimen is titrated. Calculate the strength of the K Fe(CN)
4 6
14. Reagents
solution in terms of grams of zinc as follows:
14.1 Acetone Solution of 8-Hydroxyquinoline (50 g/L)—
Z 5 W/~V 2 B !
3 2
Dissolve5gof 8-hydroxyquinoline in 100 mL of acetone.
where:
15. Procedure
Z 5 zinc equivalent of the K Fe(CN) solution, g/mL,
4 6
W 5 zinc used (or equivalent to the ZnO used), g,
15.1 Pipet 50 mL of the solution of the specimen (Section 9)
V 5 K Fe(CN) solution required for titration of the
into a 250-mL beaker and dilute to 100 mL with water. Add 5 3 4 6
standard, g, and
to 10 g of ammonium chloride (NH Cl) and heat to boiling.
B 5 K Fe(CN) solution required for titration of the
2 4 6
Add a slight excess of ammonium hydroxide (NH OH) and let
blank, mL.
stand a few minutes to allow any precipitate to coagulate. Filter
16.3 Thymol Blue Indicator Solution (0.5 g/L)—Dissolve
through an ashless, rapid paper into a 400-mL beaker and
0.1 g of thymol blue indicator in 200-mL of methanol, ethanol,
wash.
or isopropanol.
15.2 Heat the filtrate to boiling and add 5 mL of NH OH (sp
gr 0.90). Add dropwise 10 mL of the acetone solution of
16.4 Uranyl Acetate Indicator Solution (50 g/L)—Dissolve
8-hydroxyquinoline (Note 6). Let stand 10 to 20 min and filter
5gofUO (C H O ) ·H O in water made slightly acid with
2 2 3 2 2 2
through a medium-porosity sintered-glass crucible. Wash well
acetic acid and dilute to 100 mL.
with water.
17. Procedure
NOTE 6—The reagent is used in acetone solution rather than alcohol
solution to eliminate the danger of reducing some of the chromate by
17.1 Pipet 50 mL of the solution of the specimen (Section 9)
alcohol. Avoid adding an excess of reagent and lengthy boiling after its
into a 400-mL beaker. Add 35 mL of H SO (1+5) and 3 to 4
2 4
addition. Ten millilitres of hydroxyquinoline (50 g/L) is sufficient for a
drops of thymol blue indicator solution. First add NH OH (sp
normal zinc yellow. The solution can be tested for complete precipitation, 4
gr 0.90) and finally NH OH (1+10) until the color of the
but since the reagent itself is rather insoluble, the results may be
misleading. The insoluble reagent will dissolve in a hot solution and also indicator changes to a salmon shade intermediate between pink
in an excess of alcohol or acetone, whereas the zinc oxyquinolate will not.
and yellow. This gives a pH of about 2.4. Dilute the solution to
300 mL and heat to just under boiling. Pass in HSata
15.3 Dry the precipitate at 165°C for at least 2 h and weigh
moderate rate for 40 min. Allow the precipitate to settle for 1
as zinc oxyquinolate.
h and filter. Wash the filter ten times with water saturated with
15.4 Calculation—Calculate the percent zinc A as zinc
hydrogen sulfide gas (H S).
oxide (ZnO), as follows:
17.2 Dissolve the precipitate in hot HCl (1+3) and wash the
A 5 P 3 0.2303 /S 3 100
@~ ! #
filter paper well with hot water. Boil out the H S, neutralize to
where:
methyl orange with NH OH, and dilute to 300 mL. Add2gof
P 5 zinc oxyquinolate, g, and
NH Cl and 3 mL of HCl (sp gr 1.19), and heat to boiling.
S 5 specimen in aliquot used, g.
17.3 Titrate the hot solution with K Fe(CN) solution
4 6
0.2303 5 ZnO/zinc oxyquinolate 5 81.38/353.37
(16.2), using uranyl acetate as an external indicator on a spot
plate or 1 to 2 drops of ferrous ammonium sulfate solution as
ZINC BY THE FERROCYANIDE TEST METHOD
an internal indicator.
17.4 Calculation—Calculate the percent zinc A as ZnO, as
16. Reagents
follows:
16.1 Methyl Orange Indicator Solution— Dissolve 0.1 g of
methyl orange in 100 mL of water. A 5 ~V Z/S ! 3 100
4 4
16.2 Potassium Ferrocyanide, Standard Solution—Dissolve
where:
22 g of potassium ferrocyanide (K Fe(CN) ·3H O) in water
4 6 2
V 5 K Fe(CN) solution required for titration of the
4 4 6
and dilute to 1 L. To standardize, transfer 0.2 g of metallic zinc
specimen, mL,
or freshly ignited ZnO to a 400-mL beaker. Dissolve in 10 mL
D 444
21. Procedure
Z 5 ZnO equivalent of the K Fe(CN) solution, g/mL,
4 6
and
21.1 For this determination take about 20 g of Type I
S 5 specimen in the aliquot used, g.
pigment or about5gof Type II pigment as defined in
Specification D 478. Weigh the specimen into a 1-L beaker.
ALKALINE SALTS
Add 75 mL of HCl (sp gr 1
...
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