ASTM D4450-85(2002)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D4450–85(Reapproved2002)
Standard Test Method for
Analysis of Zinc Hydroxy Phosphite Pigment
This standard is issued under the fixed designation D 4450; 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 5. Purity of Reagents
1.1 This test method is intended for the determination of 5.1 Reagent grade chemicals shall be used in all tests.
zinc oxide and phosphorous acid content of the pigment Unless otherwise indicated, it is intended that all reagents shall
commercially known as zinc hydroxy phosphite. The zinc conform to the specifications of the Committee on Analytical
content is determined by ethylenediaminetetraacetate (EDTA) Reagents of the American Chemical Society, where such
titration and calculated as zinc oxide (ZnO), while the phos- specifications are available. Other grades may be used, pro-
phorus content is determined colorimetrically and calculated as vided it is first ascertained that the reagent is of sufficiently
phosphorous acid (H PO ). high purity to permit its use without lessening the accuracy of
3 3
1.2 The analytical procedures appear in the following order: the determination.
5.2 Unless otherwise indicated, references to water shall be
Sections
understood to mean reagent water conforming to Type II of
Zinc oxide 6 through 8
Specification D 1193.
Phosphorous acid 9 through 14
1.3 This standard does not purport to address all of the TOTAL ZINC AS ZINC OXIDE
safety concerns, if any, associated with its use. It is the
6. Reagents
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 6.1 Ammonium Hydroxide (sp gr 0.90), concentrated am-
monium hydroxide (NH OH).
bility of regulatory limitations prior to use.
6.2 Glacial Acetic Acid (min 99.7 %), concentrated glacial
2. Referenced Documents
acetic acid (CH COOH).
2.1 ASTM Standards: 6.3 Acid Ammonium Acetate Buffer—Mix 400 mL of dis-
D 1193 Specification for Reagent Water tilledwaterand400mLofreagentgradeammoniumhydroxide
(sp gr 0.90). Add 375 mL of reagent grade glacial acetic acid
3. Summary of Test Method
slowly while stirring.
3.1 The zinc is determined by dissolving the test sample in 6.4 Cupric Sulfate Solution (0.1 M)—Dissolve 25 g of
nitric acid, adjusting the pH of the solution to 5 to 5.5 and
CuSO ·5H O in distilled water and dilute to 1 L.
4 2
titrating with EDTA. 6.5 Disodium Ethylenediaminetetraacetate Dihydrate (0.05
3.2 The phosphorus is determined colorimetrically with the
M) (EDTASolution)—Dissolve 18.6 g of the reagent grade salt
aid of nitric acid, ammonium vanadate, and ammonium mo- in distilled water and dilute to 1 L. Standardize the solution as
lybdate. The absorbance of the test sample is compared to a
follows:
calibration curve that yields the number of milligrams of 6.5.1 Transfer 25 mL of lead standard (6.6) to a 400-mL
phosphorus.
beaker.Addconcentratedammoniumhydroxide(6.1)dropwise
until a permanent precipitate just forms. Add 25 mL of acid
4. Significance and Use
ammonium acetate (6.3), dilute to 200 mL, heat to boiling, add
4.1 This test method may be used to confirm the stated zinc
4 drops of copper EDTA (6.7) and 12 drops of PAN (6.8), and
oxide and phosphorous acid content of zinc hydroxy phosphite
titrate with EDTA to a clear yellow.
pigment.
6.5.2 Calculate the molarity of the EDTA, M, as follows:
Reagent Chemicals, American Chemical Society Specifications, American
This test method is under the jurisdiction of ASTM Committee D01 on Paint Chemical Society, Washington, DC. For suggestions on the testing of reagents not
and Related Coatings, Materials, andApplications and is the direct responsibility of listed by the American Chemical Society, see Analar Standards for Laboratory
Subcommittee D01.31 on Pigment Specifications. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Current edition approved Jan. 25, 1985. Published December 1985. and National Formulary, U.S. Pharmaceutical 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.
D4450–85 (2002)
M 5 25 3 0.01036/L 3 0.20721 (1)
9.6 Nitric Acid (sp gr 1.42), concentrated nitric acid
(HNO ).
where L = EDTAsolution, mL.Also 1 mLof primary standard 3
9.7 Nitric Acid (2:3)—Dilute 200 mL of nitric acid (sp gr
0.05 M lead nitrate = 0.01036 g of lead and 0.20721 is the
1.42) to 500 mL with water.
milliequivalent weight of lead.
6.6 Primary Standard (0.05 M lead nitrate)—Dissolve
10. Apparatus
16.5615 g reagent grade lead nitrate in distilled water and
10.1 Photoelectric Colorimeter, either a single- or double-
dilute to 1 L (1 mL = 0.01036 g lead).
beam spectrophotometer with a wavelength capability of 465
6.7 Copper-EDTA Solution—Mix equivalent amounts of
µm.
cupric sulfate solution (6.4) and EDTAsolution (6.5) and store
10.2 Volumetric Flasks, 100-mL.
in a dropping bottle.The cupric sulfate EDTAequivalence may
10.3 Tubes, 10-mm or 20-mm.
be determined as follows:
10.4 Filter Paper, medium texture.
6.7.1 Pipet 10 mL of cupric sulfate into a beaker, and add
concentrated ammonium hydroxide (6.1) dropwise until the
11. Calibration Curve
precipitate that forms just redissolves. Dilute to 200 mL with
11.1 Transfer from a pipet 0.0, 1.0, 3.0, 7.0, 10.0, 15.0, and
water, add two Murexide indicator tablets, crush with a stirring
20.0-mL aliquots of standard phosphorus solution (9.1) to a
rod to dissolve, and titrate immediately with EDTA to purple.
100-
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