ASTM D1844-86(2020)
(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
3.1 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 D1648).
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 trioxide
15 to 23
Silica
24 to 27
Moisture and other volatile matter
28
Coarse particles
29
Oil absorption
30
Mass color and tinting strength
31
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 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1844 − 86 (Reapproved 2020)
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 2. Referenced Documents
1.1 These test methods cover the chemical analysis of the 2.1 ASTM Standards:
D185Test Methods for Coarse Particles in Pigments
pigment commercially known as basic lead silicochromate and
are applicable to pigment supplied by the manufacturer and to D280Test Methods for Hygroscopic Moisture (and Other
Matter Volatile Under the Test Conditions) in Pigments
pigment, but not mixed pigments, separated from liquid
D281Test Method for Oil Absorption of Pigments by
coatings. The presence of basic lead silicochromate species
Spatula Rub-out
shall be confirmed by X-ray diffraction analysis (see Specifi-
D387Test Method for Color and Strength of Chromatic
cation D1648).
Pigments with a Mechanical Muller
1.2 For liquid coatings the pigment must first be separated
D1193Specification for Reagent Water
from the vehicle before conducting the analysis.
D1648SpecificationforBasicLeadSilicochromatePigment
1.3 Theanalyticalproceduresappearinthefollowingorder:
D2371 Test Method for Pigment Content of Solvent-
Sections
Reducible Paints
Lead oxide 6 to 14
Chromium trioxide 15 to 23
3. Significance and Use
Silica 24 to 27
3.1 These test methods may be used to confirm the stated
Moisture and other volatile matter 28
Coarse particles 29
lead oxide, chromium trioxide and silica content of basic lead
Oil absorption 30
silicochromate and is useful for quality control.
Mass color and tinting strength 31
4. Purity of Reagents
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
4.1 Reagent grade chemicals shall be used in all tests.
only.
Unlessotherwiseindicated,itisintendedthatallreagentsshall
1.5 This standard does not purport to address all of the conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- specifications are available. Other grades may be used, pro-
vided it is first ascertained that the reagent is of sufficiently
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. high purity to permit its use without lessening the accuracy of
the determination.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.2 Unless otherwise indicated, references to water shall be
ization established in the Decision on Principles for the
understood to mean reagent water conforming to Type II of
Development of International Standards, Guides and Recom-
Specification D1193.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
These test methods are under the jurisdiction of ASTM Committee D01 on ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Paint and Related Coatings, Materials, and Applications and are the direct
Standard-Grade Reference Materials, American Chemical Society, Washington,
responsibility of Subcommittee D01.31 on Pigment Specifications.
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Current edition approved June 1, 2020. Published June 2020. Originally
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
approved in 1961. Last previous edition approved in 2014 as D1844–86(2014). U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
DOI: 10.1520/D1844-86R20. copeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1844 − 86 (2020)
5. Preparation of Sample (1+1). Destroy the organic material by evaporating the
solution to dense white fumes, making further additions of
5.1 Thoroughly mix liquid coatings and separate in accor-
HNO until there is no charring.
dancewithTestMethodD2371sufficientpigmenttoenablethe
required analyses to be carried out.
8.3 Cool the solution, add 10 mLof water, and evaporate to
fumes. Repeat the addition of water and the evaporation. Cool
5.2 Thoroughly mix pigment supplied as such and grind
the solution, add 40 mL of water, and bring the solution to
separated pigment to a fine powder in a mortar and pestle
boiling. Cool the solution and add 50 mLof isopropyl alcohol
before taking portions for analysis.
(98%), stir, and allow the solution to stand cold for at least 4
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).
where:
7.6 Hydrogen Sulfide (H S)—Handle and use H S in hood.
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
5 0.6906 3100 forpercent 5 69.06
~ !
saturatedsolutionofpotassiumdichromate(K Cr O )inwater.
323.21
2 2 7
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
PbCrO to grams of PbO.
of water.
This gravimetric factor has led to high results due to the
presence of mixed lead chromates and an empirical factor can
8. Procedure
be used to compensate:
8.1 Weigh accurately (to 0.1 mg)1gofthe sample into a
Empiricalfactor 5 69.06 30.9944 5 68.67
platinum dish. Add 5 mL of HNO and 10 mL of HF.
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
LEADOXIDE—TITRIMETRIC METHOD
dryness. Wash the sides of the dish with a little water and
evaporate to dryness. Wet the residue with 5 mL of HNO ,
3 10. Apparatus
warmgently,andtransfertheresiduetoa400-mLbeakerusing
10.1 Platinum Dish.
a policeman. Neutralize with NH OH, and then make the
solution just acid with HCl, adding 5 mL in excess. Dilute to
10.2 Filter Paper, ashless, medium texture, or paper pulp.
200 mL and heat to just below the boiling point until solution
is complete.
11. Reagents
8.2 Pass H S through the solution for about 20 min. Filter,
11.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
using paper pulp. Wash the precipitate five to six times with
monium hydroxide (NH OH).
water just acid with HCl and saturated with H S. Transfer the
paper and precipitate to the original beaker, add 25 mL of 11.2 Glacial Acetic Acid (min 99.7 %)—Concentrated gla-
HNO ,boiluntiltheresidueiswhite,thenadd10mLofH SO cial acetic acid (CH COOH).
3 2 4 3
D1844 − 86 (2020)
11.3 Acid Ammonium Acetate Buffer—Mix 400 mL of dis- 11.15 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
tilled water and 400 mLof ammonium hydroxide (sp gr 0.90). concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
Add 375 mL of reagent grade glacial acetic acid slowly while of water.
stirring.
12. Procedure
11.4 Cupric Sulfate Solution (0.1 M)—Dissolve 25 g of
12.1 Dissolve1gof pigment in accordance with 8.1 and
CuSO ·5H O in distilled water and dilute to 1 L.
4 2
8.2.
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
0.05 M×0.22321=0.01116gPbOin1mLofleadstandard where:
(11.14).
V = EDTA required for titration, mL,
25 mL × 0.05 M × 0.22321g/mmol =0.2790 g PbO in 25
L = lead equivalent of EDTA solution, and
mL of lead standard (11.14). S = specimen weight, g.
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
15.1 Soluble Fe will cause high results. See Section 20.
11.12 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
(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.
16.3 Hydrochloric Acid Mixture—Saturate water with NaCl
(about 350 g/L). To each litre of this solution add 150 mL of
The standardized solution may also be purchased from Corco Chemical Corp.
Catalog No.—Special. water and 100 mL of concentrated HCl (sp gr 1.19).
D1844 − 86 (2020)
16.4 Sodium Thiosulfate Solution (0.1 N)—Dissolve 24.8 g ALTERNATIVE METHOD FOR CHROMIUM
of reagent grade Na S O ·5H O in recently boiled water and TRIOXIDE
2 2 3 2
dilute to 1 L with additional recently boiled water. To
19. Scope
standardize,pipet25mLofthestandardpotassiumdichromate
solution (exactly 0.1000 N) into a 250-mL Erlenmeyer flask.
19.1 This test method determines total chromium as chro-
Add100mLofwater,15mLofpotassiumiodidesolution,and
mium trioxide. Iron oxide interference is masked by the use of
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 so
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.