ASTM D1844-86(2008)
(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 analytical procedures appear in the following order:
Sections
Lead oxide 6 to 14 Chromium trioxide15 to 23 Silica24 to 27 Moisture and other volatile matter28 Coarse particles29 Oil absorption30 Mass color and tinting strength31
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D1844 − 86(Reapproved 2008)
Standard Test Methods for
Chemical Analysis of Basic Lead Silicochromate
This standard is issued under the fixed designation D1844; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D281Test Method for Oil Absorption of Pigments by
Spatula Rub-out
1.1 These test methods cover the chemical analysis of the
D387Test Method for Color and Strength of Chromatic
pigment commercially known as basic lead silicochromate and
Pigments with a Mechanical Muller
are applicable to pigment supplied by the manufacturer and to
D1193Specification for Reagent Water
pigment, but not mixed pigments, separated from liquid
D1648SpecificationforBasicLeadSilicochromatePigment
coatings. The presence of basic lead silicochromate species
D2371 Test Method for Pigment Content of Solvent-
shall be confirmed by X-ray diffraction analysis (see Specifi-
Reducible Paints
cation D1648).
1.2 For liquid coatings the pigment must first be separated
3. Significance and Use
from the vehicle before conducting the analysis.
3.1 These test methods may be used to confirm the stated
1.3 Theanalyticalproceduresappearinthefollowingorder:
lead oxide, chromium trioxide and silica content of basic lead
Sections
silicochromate and is useful for quality control.
Lead oxide 6 to 14
Chromium trioxide 15 to 23
4. Purity of Reagents
Silica 24 to 27
Moisture and other volatile matter 28
4.1 Reagent grade chemicals shall be used in all tests.
Coarse particles 29
Unlessotherwiseindicated,itisintendedthatallreagentsshall
Oil absorption 30
Mass color and tinting strength 31
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
1.4 The values stated in SI units are to be regarded as the
specifications are available. Other grades may be used, pro-
standard. The values given in parentheses are for information
only. vided it is first ascertained that the reagent is of sufficiently
high purity to permit its use without lessening the accuracy of
1.5 This standard does not purport to address the safety
the determination.
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
4.2 Unless otherwise indicated, references to water shall be
health practices and determine the applicability of regulatory
understood to mean reagent water conforming to Type II of
limitations prior to use.
Specification D1193.
2. Referenced Documents
5. Preparation of Sample
2.1 ASTM Standards:
5.1 Thoroughly mix liquid coatings and separate in accor-
D185Test Methods for Coarse Particles in Pigments
dancewithTestMethodD2371sufficientpigmenttoenablethe
D280Test Methods for Hygroscopic Moisture (and Other
required analyses to be carried out.
Matter Volatile Under the Test Conditions) in Pigments
5.2 Thoroughly mix pigment supplied as such and grind
separated pigment to a fine powder in a mortar and pestle
before taking portions for analysis.
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 July 1, 2008. Published August 2008. Originally
approved in 1961. Last previous edition approved in 2003 as D1844–86(2003). Reagent Chemicals, American Chemical Society Specifications , American
DOI: 10.1520/D1844-86R08. 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.PharmacopeialConvention,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 (2008)
TOTAL LEAD AS LEAD OXIDE-GRAVIMETRIC h. Filter, using paper pulp, and wash once with cold isopropyl
METHOD alcohol (50%) containing 10 mL of H SO (sp gr 1.84)/100
2 4
mL.
6. Apparatus
8.4 Transfer the precipitate to the original beaker with 150
6.1 Glass Filtering Crucible(medium-porosityfritteddisk),
mLofwater,add50mLoftheammoniumacetatesolution,and
dried to constant weight before use.
boilthesolutionuntiltheleadsulfatedissolves.Filterwhilehot
6.2 Platinum Dish.
through the original paper and wash well (6 to 8 washes) with
hot water. To the filtrate add 5 mL of glacial acetic acid, heat
7. Reagents
the solution to boiling, and add 20 mL of saturated K Cr O
2 2 7
7.1 Acetic Acid (Glacial).
solution. Boil the solution until the precipitate turns orange,
and allow to stand on a warm plate for at least 2 h. Filter
7.2 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
through a glass filtering crucible (medium-porosity fritted
monium hydroxide (NH OH).
disk), wash three times with hot water, and finally once with
7.3 AmmoniumAcetate,Acid Solution—To300mLofwater
alcohol. Dry in an oven at 105°C for 2 h, cool, and weigh.
add an equal volume of NH OH. Neutralize with glacial acetic
acid and add 20 mL in excess.
9. Calculation
7.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
9.1 Calculatethepercentoftotalleadasleadoxide(PbO)as
chloric acid (HCl).
follows:
7.5 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
PbO, % 5 P 369.06 /S
acid (HF). ~ !
7.6 Hydrogen Sulfide (H S)—Handle and use H S in hood.
where:
2 2
P = lead chromate (PbCrO ) precipitate, g,
7.7 Isopropyl Alcohol (50 and 98%).
S = sample used, g, and
7.8 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
molecularweight PbO
(HNO ). ~ !
molecularweight ~PbCrO )
7.9 Potassium Dichromate Solution (saturated)—Prepare a
223.21
saturatedsolutionofpotassiumdichromate(K Cr O )inwater.
2 2 7 5 0.6906 3100 ~forpercent! 5 69.06
323.21
7.10 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
69.06 represents the gravimetric factor to convert grams of
concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
of water. PbCrO to grams of PbO.
This gravimetric factor has led to high results due to the
8. Procedure
presence of mixed lead chromates and an empirical factor can
be used to compensate:
8.1 Weigh accurately (to 0.1 mg)1gofthe sample into a
platinum dish. Add 5 mL of HNO and 10 mL of HF.
Empiricalfactor 5 69.06 30.9944 5 68.67
Cautiously evaporate to dryness on a steam bath. Repeat the
ALTERNATIVE METHOD FOR TOTAL LEAD AS
addition of HNO and HF and again cautiously evaporate to
dryness. Wash the sides of the dish with a little water and LEADOXIDE—TITRIMETRIC METHOD
evaporate to dryness. Wet the residue with 5 mL of HNO ,
warmgently,andtransfertheresiduetoa400-mLbeakerusing
10. Apparatus
a policeman. Neutralize with NH OH, and then make the
10.1 Platinum Dish.
solution just acid with HCl, adding 5 mL in excess. Dilute to
200 mL and heat to just below the boiling point until solution
10.2 Filter Paper, ashless, medium texture, or paper pulp.
is complete.
11. Reagents
8.2 Pass H S through the solution for about 20 min. Filter,
using paper pulp. Wash the precipitate five to six times with
11.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
water just acid with HCl and saturated with H S. Transfer the
monium hydroxide (NH OH).
paper and precipitate to the original beaker, add 25 mL of
HNO ,boiluntiltheresidueiswhite,thenadd10mLofH SO
11.2 Glacial Acetic Acid (min 99.7 %)—Concentrated gla-
3 2 4
(1+1). Destroy the organic material by evaporating the
cial acetic acid (CH COOH).
solution to dense white fumes, making further additions of
11.3 Acid Ammonium Acetate Buffer—Mix 400 mL of dis-
HNO until there is no charring.
tilled water and 400 mLof ammonium hydroxide (sp gr 0.90).
8.3 Cool the solution, add 10 mLof water, and evaporate to
Add 375 mL of reagent grade glacial acetic acid slowly while
fumes. Repeat the addition of water and the evaporation. Cool
stirring.
the solution, add 40 mL of water, and bring the solution to
11.4 Cupric Sulfate Solution (0.1 M)—Dissolve 25 g of
boiling. Cool the solution and add 50 mLof isopropyl alcohol
(98%), stir, and allow the solution to stand cold for at least 4 CuSO ·5H O in distilled water and dilute to 1 L.
4 2
D1844 − 86 (2008)
11.5 Disodium Ethylenediaminetetracetate Dihydrate (0.05 12.2 Cool, so that the addition of 25 mL of water does not
M) (EDTA solution) —Dissolve 18.6 g of the salt in distilled cause excessive splattering of the sulfuric acid; the solution at
water and dilute to 1 L. Standardize the solution as follows: this point should be water white. Add ammonium hydroxide
Transfer 25 mL of lead standard (11.14) to a 400-mL beaker. (spgr0.90)untilthepHofthesolutionis5to5.5(asindicated
Add concentrated ammonium hydroxide (11.1) dropwise until by pH paper). Add 50 mL of acid ammonium acetate (11.3),
a permanent precipitate just forms. Add 25 mL of acid boil 5 min, dilute to 200 mLwith water, heat to boiling, add 4
ammonium acetate (11.3), dilute to 200 mL, heat to boiling, dropsofcopper-EDTA(11.7)and12dropsofPAN(11.13)and
add 4 drops of copper EDTA (11.7) and 12 drops of PAN titrate while hot with standard EDTA to a clear yellow.
(11.13) and titrate with the EDTA to a clear yellow.
13. Calculation
1mLNa EDTA 5 0.2790/V g PbO
13.1 Calculate the percent lead oxide as follows:
where:
V 3L 3100
V = EDTA required for titration, mL PbO, % 5
S
g = lead oxide, g, and
where:
0.05 M×0.22321=0.01116gPbOin1mLofleadstandard
V = EDTA required for titration, mL,
(11.14).
L = lead equivalent of EDTA solution, and
25 mL × 0.05 M × 0.22321g/mmol =0.2790 g PbO in 25
S = specimen weight, g.
mL of lead standard (11.14).
11.6 Murexide Indicator Tablets—Ammonium salt of pur-
14. Precision and Bias
puric acid.
14.1 On the basis of an interlaboratory study of the method
11.7 Copper-EDTA Solution—Mix equivalent amounts of
in which operators in three laboratories analyzed two paints
cupric sulfate solution (11.4) and EDTA solution (11.5) and
containing basic lead silicochromate with iron oxide the
store in a dropping bottle. The cupric sulfate EDTA equiva-
following criteria should be used for judging the acceptability
lence may be determined as follows: Pipet 10 mL of cupric
of the results at the 95% confidence level:
sulfate into a beaker, add concentrated ammonium hydroxide
14.1.1 Repeatability—Two results, each the mean of dupli-
dropwise until the precipitate which forms just redissolves.
cate determinations obtained by the same operator should be
Dilute to 200 mL with water, add two Murexide indicator
considered suspect if they differ by more than the following:
tablets, and titrate immediately with EDTA to a color change
Percent Absolute PbO
from yellow to purple.
28 % 0.20
45 % 0.30
11.8 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
14.1.2 Reproducibility—A realistic range could not be es-
chloric acid (HCl).
tablished for results between laboratories because of the
11.9 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
limited number of participating laboratories.
acid (HF).
14.1.3 Bias—A bias statement could not be established
11.10 Hydrogen Sulfide (H S)—Cylinder. Handle and use in because of the limited number of participating laboratories.
a hood.
CHROMIUM TRIOXIDE
11.11 Hydrogen Sulfide Wash Solution—Add 10 mLof HCl
(sp gr 1.19) to 1 L of water and saturate with H S. 15. Interference
+3
11.12 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
15.1 Soluble Fe will cause high results. See Section 20.
(HNO ).
16. Reagents
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
11.14 Primary Standard (0.05 M lead nitrate)—Dissolve
dissolveitinwater,anddiluteto1Lwithwaterinavolumetric
16.5615 g of reagent grade lead nitrate in distilled water and
flask.
dilute to 1 L.
16.2 Potassium Iodide Solution (150 g/L)—Dissolve 150 g
1mL 5 0.01116g PbO
of potassium iodide (KI) in water and dilute to 1 L.
11.15 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
16.3 Hydrochloric Acid Mixture—Saturate water with NaCl
concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
(about 350 g/L). To each litre of this solution add 150 mL of
of water.
water and 100 mL of concentrated HCl (sp gr 1.19).
12. Procedure
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
12.1 Dissolve1gof pigment in accordance with 8.1 and
2 2 3 2
8.2. dilute to 1 L with additional recently boiled water. To
standardize,pipet25mLofthestandardpotassiumdichromate
solution (exactly 0.1000 N) into a 250-mL Erlenmeyer flask.
The standardized solution may also be purchased from Corco Chemical Corp.
Catalog No.—Special. Add100mLofwater,15mLofpotassiumiodidesolution,and
D1844 − 86 (2008)
15 mL of concentrated hydrochloric acid (sp gr 1.19). Titrate EDTA.Thisprocedureisnotapplicablewhenchromiumoxide
the liberated iodine with sodium thiosulfate solution until the green (Cr O ) is present. This test method is limited to basic
2 3
reddish-brown color becomes quite faint. Add 5 mL of starch lead silicochromate pigments with or without iron oxide.
solutionandcontinuethetitrationdropwiseuntilthebluecolor
19.2 The perchloric acid is employed as an oxidizing agent
changes to a pale green. Calculate the normality of the sodium
to ensure complete oxidation of any reduced chromium.When
thiosulfate solution as follows:
perchloric acid is used, concentrated nitric acid must also be
2.5000
used. The use of a perchloric acid hood is optional since the
N 5
M
specimen is covered with a watch glass and is being oxidized,
not wet ashed.
where:
N = normality, and
20. Reagents
M = sodium thiosulfate solution, mL,
20.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
16.5 StarchIndicatorSolution—Makeahomogeneouspaste
monium hydroxide (NH OH).
of 10 g of soluble starch in cold water. Add to this 1 L of
20.2 Disodium Ethylenediaminetetracetate Dihydrate
boiling water, stir rapidly, and cool. Salicylic acid (1.25 g/L)
(0.05 M) (EDTA)—Dissolve 18.6 g of the reagent grade salt in
may be added to preserve the indicator. If long stora
...
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