ASTM D1844-86(2003)
(Test Method)Standard Test Methods for Chemical Analysis of Basic Lead Silicochromate
Standard Test Methods for Chemical Analysis of Basic Lead Silicochromate
SIGNIFICANCE AND USE
These test methods may be used to confirm the stated lead oxide, chromium trioxide and silica content of basic lead silicochromate and is useful for quality control.
SCOPE
1.1 These test methods cover the chemical analysis of the pigment commercially known as basic lead silicochromate and are applicable to pigment supplied by the manufacturer and to pigment, but not mixed pigments, separated from liquid coatings. The presence of basic lead silicochromate species shall be confirmed by X-ray diffraction analysis (see Specification D 1648).
1.2 For liquid coatings the pigment must first be separated from the vehicle before conducting the analysis.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address 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:D1844–86(Reapproved2003)
Standard Test Methods for
Chemical Analysis of Basic Lead Silicochromate
This standard is issued under the fixed designation D 1844; 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 D 280 Test Methods for Hygroscopic Moisture (and Other
Matter Volatile Under the Test Conditions) in Pigments
1.1 These test methods cover the chemical analysis of the
D 281 Test Method for Oil Absorption of Pigments by
pigment commercially known as basic lead silicochromate and
Spatula Rub-Out
are applicable to pigment supplied by the manufacturer and to
D 387 Test Method for Color and Strength of Color Pig-
pigment, but not mixed pigments, separated from liquid
ments with a Mechanical Muller
coatings. The presence of basic lead silicochromate species
D 1193 Specification for Reagent Water
shall be confirmed by X-ray diffraction analysis (see Specifi-
D 1648 Specification for Basic Lead Silicochromate Pig-
cation D 1648).
ment
1.2 For liquid coatings the pigment must first be separated
D 2371 Test Method for Pigment Content of Solvent-
from the vehicle before conducting the analysis.
Reducible Paints
1.3 The analytical procedures appear in the following order:
Sections
3. Significance and Use
Lead oxide 6 to 14
3.1 These test methods may be used to confirm the stated
Chromium trioxide 15 to 23
lead oxide, chromium trioxide and silica content of basic lead
Silica 24 to 27
silicochromate and is useful for quality control.
Moisture and other volatile matter 28
Coarse particles 29
Oil absorption 30
4. Purity of Reagents
Mass color and tinting strength 31
4.1 Reagent grade chemicals shall be used in all tests.
1.4 The values stated in SI units are to be regarded as the
Unless otherwise indicated, it is intended that all reagents shall
standard. The values given in parentheses are for information
conform to the specifications of the Committee on Analytical
only.
Reagents of the American Chemical Society, where such
1.5 This standard does not purport to address the safety
specifications are available. Other grades may be used, pro-
concerns, if any, associated with its use. It is the responsibility
vided it is first ascertained that the reagent is of sufficiently
of the user of this standard to establish appropriate safety and
high purity to permit its use without lessening the accuracy of
health practices and determine the applicability of regulatory
the determination.
limitations prior to use.
4.2 Unless otherwise indicated, references to water shall be
understood to mean reagent water conforming to Type II of
2. Referenced Documents
Specification D 1193.
2.1 ASTM Standards:
D 185 Test Methods for Coarse Particles in Pigments, 5. Preparation of Sample
Pastes, and Paints
5.1 Thoroughly mix liquid coatings and separate in accor-
dance with Test Method D 2371 sufficient pigment to enable
1 the required analyses to be carried out.
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct
responsibility of Subcommittee D01.31 on Pigment Specifications.
Current edition approved Dec. 1, 2003. Published December 2003. Originally Reagent Chemicals, American Chemical Society Specifications, American
approved in 1961. Last previous edition approved in 1986 as D 1844 – 86 (1999). Chemical Society, Washington, DC. For suggestions on the testing of reagents not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmacopeial Convention, Inc., (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1844–86 (2003)
5.2 Thoroughly mix pigment supplied as such and grind h. Filter, using paper pulp, and wash once with cold isopropyl
separated pigment to a fine powder in a mortar and pestle alcohol (50 %) containing 10 mL of H SO (sp gr 1.84)/100
2 4
before taking portions for analysis. mL.
8.4 Transfer the precipitate to the original beaker with 150
TOTAL LEAD AS LEAD OXIDE-GRAVIMETRIC mLofwater,add50mLoftheammoniumacetatesolution,and
METHOD boilthesolutionuntiltheleadsulfatedissolves.Filterwhilehot
through the original paper and wash well (6 to 8 washes) with
6. Apparatus hot water. To the filtrate add 5 mL of glacial acetic acid, heat
the solution to boiling, and add 20 mL of saturated K Cr O
2 2 7
6.1 Glass Filtering Crucible (medium-porosity fritted
solution. Boil the solution until the precipitate turns orange,
disk), dried to constant weight before use.
and allow to stand on a warm plate for at least 2 h. Filter
6.2 Platinum Dish.
through a glass filtering crucible (medium-porosity fritted
disk), wash three times with hot water, and finally once with
7. Reagents
alcohol. Dry in an oven at 105°C for 2 h, cool, and weigh.
7.1 Acetic Acid (Glacial).
7.2 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
9. Calculation
monium hydroxide (NH OH).
9.1 Calculatethepercentoftotalleadasleadoxide(PbO)as
7.3 AmmoniumAcetate,Acid Solution—To300mLofwater
follows:
add an equal volume of NH OH. Neutralize with glacial acetic
PbO, % 5 P 3 69.06!/S
~
acid and add 20 mL in excess.
7.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
where:
chloric acid (HCl).
P = lead chromate (PbCrO ) precipitate, g,
7.5 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
S = sample used, g, and
acid (HF).
molecular weight ~PbO!
7.6 Hydrogen Sulfide (H S)—Handle and use H S in hood.
2 2
molecular weight ~PbCrO
7.7 Isopropyl Alcohol (50 and 98 %).
223.21
5 0.6906 3 100 ~for percent!5 69.06
7.8 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
323.21
(HNO ) (see 7.4.1).
69.06 represents the gravimetric factor to convert grams of
7.9 Potassium Dichromate Solution (saturated)—Prepare a
PbCrO to grams of PbO.
saturatedsolutionofpotassiumdichromate(K Cr O )inwater.
2 2 7
This gravimetric factor has led to high results due to the
7.10 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
presence of mixed lead chromates and an empirical factor can
concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
be used to compensate:
of water (see 7.4.1).
Empirical factor 5 69.06 3 0.9944 5 68.67
8. Procedure
ALTERNATIVE METHOD FOR TOTAL LEAD AS
8.1 Weigh accurately (to 0.1 mg)1gofthe sample into a
LEADOXIDE—TITRIMETRIC METHOD
platinum dish. Add 5 mL of HNO and 10 mL of HF.
Cautiously evaporate to dryness on a steam bath. Repeat the
10. Apparatus
addition of HNO and HF and again cautiously evaporate to
10.1 Platinum Dish.
dryness. Wash the sides of the dish with a little water and
10.2 Filter Paper, ashless, medium texture, or paper pulp.
evaporate to dryness. Wet the residue with 5 mL of HNO ,
warm gently, and transfer the residue to a 400-mLbeaker using
11. Reagents
a policeman. Neutralize with NH OH, and then make the
11.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
solution just acid with HCl, adding 5 mL in excess. Dilute to
monium hydroxide (NH OH).
200 mL and heat to just below the boiling point until solution
11.2 Glacial Acetic Acid (min 99.7 %)—Concentrated gla-
is complete.
cial acetic acid (CH COOH).
8.2 Pass H S through the solution for about 20 min. Filter,
11.3 Acid Ammonium Acetate Buffer—Mix 400 mL of
using paper pulp. Wash the precipitate five to six times with
distilled water and 400 mL of ammonium hydroxide (sp gr
water just acid with HCl and saturated with H S. Transfer the
0.90). Add 375 mL of reagent grade glacial acetic acid slowly
paper and precipitate to the original beaker, add 25 mL of
while stirring.
HNO ,boiluntiltheresidueiswhite,thenadd10mLofH SO
3 2 4
11.4 Cupric Sulfate Solution (0.1M)—Dissolve 25 g of
(1 + 1). Destroy the organic material by evaporating the
CuSO ·5H O in distilled water and dilute to 1 L.
4 2
solution to dense white fumes, making further additions of
11.5 Disodium Ethylenediaminetetracetate Dihydrate (0.05
HNO until there is no charring. 4
M) (EDTA solution) —Dissolve 18.6 g of the salt in distilled
8.3 Cool the solution, add 10 mLof water, and evaporate to
water and dilute to 1 L. Standardize the solution as follows:
fumes. Repeat the addition of water and the evaporation. Cool
the solution, add 40 mL of water, and bring the solution to
boiling. Cool the solution and add 50 mL of isopropyl alcohol
The standardized solution may also be purchased from Corco Chemical Corp.
(98 %), stir, and allow the solution to stand cold for at least 4 Catalog No.—Special.
D1844–86 (2003)
Transfer 25 mL of lead standard (11.14) to a 400-mL beaker. 13. Calculation
Add concentrated ammonium hydroxide (11.1) dropwise until
13.1 Calculate the percent lead oxide as follows:
a permanent precipitate just forms. Add 25 mL of acid
V 3 L 3 100
ammonium acetate (11.3), dilute to 200 mL, heat to boiling,
PbO, % 5
S
add 4 drops of copper EDTA (11.7) and 12 drops of PAN
(11.13) and titrate with the EDTA to a clear yellow.
where:
V = EDTA required for titration, mL,
1mLNa EDTA 5 0.2790/V g PbO
L = lead equivalent of EDTA solution, and
where: S = specimen weight, g.
V = EDTA required for titration, mL
g = lead oxide, g, and
14. Precision and Bias
0.05 M 3 0.22321 = 0.01116gPbOin1mLofleadstandard
14.1 On the basis of an interlaboratory study of the method
(10.14) (25 mL) (0.05 M) (0.22321) = 0.2790 g PbO in 25 mL
in which operators in three laboratories analyzed two paints
of lead standard (10.14).
containing basic lead silicochromate with iron oxide the
11.6 Murexide Indicator Tablets—Ammonium salt of pur-
following criteria should be used for judging the acceptability
puric acid.
of the results at the 95 % confidence level:
11.7 Copper-EDTA Solution—Mix equivalent amounts of
14.1.1 Repeatability—Two results, each the mean of dupli-
cupric sulfate solution (11.4) and EDTA solution (11.5) and
cate determinations obtained by the same operator should be
store in a dropping bottle. The cupric sulfate EDTA equiva-
considered suspect if they differ by more than the following:
lence may be determined as follows: Pipet 10 mL of cupric
Percent Absolute PbO
28 % 0.20
sulfate into a beaker, add concentrated ammonium hydroxide
45 % 0.30
dropwise until the precipitate which forms just redissolves.
Dilute to 200 mL with water, add two Murexide indicator 14.1.2 Reproducibility—A realistic range could not be es-
tablets, and titrate immediately with EDTA to a color change
tablished for results between laboratories because of the
from yellow to purple.
limited number of participating laboratories.
11.8 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro- 14.1.3 Bias—A bias statement could not be established
chloric acid (HCl) (see 7.4.1). because of the limited number of participating laboratories.
11.9 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
CHROMIUM TRIOXIDE
acid (HF).
11.10 Hydrogen Sulfide(H S)—Cylinder.Handleandusein
15. Interference
a hood.
+3
11.11 Hydrogen Sulfide Wash Solution—Add 10 mLof HCl 15.1 Soluble Fe will cause high results. See Section 20
(sp gr 1.19) to 1 L of water and saturate with H S. .
11.12 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
16. Reagents
(HNO ).
11.13 Pan Indicator (1-(2-pyridylazo)-2-naphthol)— 16.1 Potassium Dichromate, Standard Solution (0.1 N)—
Dissolve 0.1 g in 100 mL of ethanol.
Weigh 4.904 g of dried potassium dichromate (K Cr O ),
2 2 7
dissolveitinwater,anddiluteto1Lwithwaterinavolumetric
11.14 Primary Standard (0.05 M lead nitrate)—Dissolve
16.5615 g of reagent grade lead nitrate in distilled water and flask.
16.2 Potassium Iodide Solution (150 g/L)—Dissolve 150 g
dilute to 1 L.
of potassium iodide (KI) in water and dilute to 1 L.
1mL 5 0.01116 g PbO
16.3 Hydrochloric Acid Mixture—Saturate water with NaCl
11.15 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
(about 350 g/L). To each litre of this solution add 150 mL of
concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
water and 100 mL of concentrated HCl (sp gr 1.19).
of water.
16.4 Sodium Thiosulfate Solution (0.1 N)—Dissolve 24.8 g
of reagent grade Na S O ·5H O in recently boiled water and
2 2 3 2
12. Procedure
dilute to 1 L with additional recently boiled water. To stan-
dardize, pipet 25 mL of the standard potassium dichromate
12.1 Dissolve1gof pigment in accordance with 8.1 and
solution (exactly 0.1000 N) into a 250-mL Erlenmeyer flask.
8.2.
Add 100 mLof water, 15 mLof potassium iodide solution, and
12.2 Cool, so that the addition of 25 mL of water does not
15 mL of concentrated hydrochloric acid (sp gr 1.19). Titrate
cause excessive splattering of the sulfuric acid; the solution at
the liberated iodine with sodium thiosulfate solution until the
this point should be water white. Add ammonium hydroxide
reddish-brown color becomes quite faint. Add 5 mL of starch
(sp gr 0.90) until the pH of the solution is 5 to 5.5 (as indicated
solution and continue the titration dropwise until the blue color
by pH paper). Add 50 mL of acid ammonium acetate (11.3),
changes to a pale green. Calculate the normality of the sodium
boil 5 min, dilute to 200 mL with water, heat to boiling, add 4
thiosulfate solution as follows:
drops of copper-EDTA (11.7) and 12 drops of PAN
(11.1311.13) and titrate while hot with standard EDTA to a 2.5000
N 5
clear yellow. M
D1844–86 (2003)
20. Reagents
where:
N = normality, and
20.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
M = sodium thiosulfate solution, mL,
monium hydroxide (NH OH).
16.5 Starch Indicator Solution—Make a homogeneous
20.2 Disodium Ethylenediaminetetracetate Dihydrate
paste of 10 g of soluble starch in cold water.Add to this 1 Lof (0.05 M) (EDTA)— Dissolve 18.6 g of the reagent grade salt in
boiling water, stir rapidly, and cool. Salicylic acid (1.25 g/L)
distilled water and dilute to 1 L. See 11.5 for standardization.
may be added to preserve the indicator. If long storage is 20.3 Hydrochloric Acid Mixture—See 16.3.
required, the solution should be kept in a refrigerator at 4 to
20.4 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
10°C (40 to 50°F). Prepare fresh indicator when the end point
acid (HF).
of the titration from blue to c
...
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