ASTM D2810-07
(Test Method)Standard Test Method for pH of Leather
Standard Test Method for pH of Leather
SIGNIFICANCE AND USE
This test method is designed to measure the pH of a distilled-water extract of leather. This is considered to be a measure of the acidity or alkalinity of the leather. Excessive acidity or alkalinity may have a deleterious effect on the aging characteristics of leather.
This test method is suitable for development, control, and service evaluation of leather.
SCOPE
1.1 This test method covers the determination of the pH of all types of leather. This method does not apply to wet blue.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D2810 − 07
StandardTest Method for
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pH of Leather
This standard is issued under the fixed designation D2810; 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 (´) 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 4.2.2 Mix with the required amount of water for 1 min in a
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disintegrator.
1.1 This test method covers the determination of the pH of
4.2.3 Extract the weighed specimen with a fat solvent in a
all types of leather. This method does not apply to wet blue.
Soxhlet apparatus for 5 h. Allow the specimen to air until all
1.2 This standard does not purport to address all of the
solvent has evaporated; then proceed as outlined in Section 9.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Apparatus
priate safety and health practices and determine the applica-
5.1 pH Meter, either battery or line-operated, with a glass
bility of regulatory limitations prior to use.
electrode and reference electrode or suitable combination
electrode. The meter shall have a resolution of 0.1/0.01 pH
2. Terminology
unit, and shall have a relative accuracy of 60.1/0.01 pH unit.
2.1 Definitions of Terms Specific to This Standard:
5.2 Analytical Balance, sensitive to 0.01 g.
2.1.1 The pH of a solution has been defined as the negative
logarithm of the hydrogen ion activity. A solution of pH 7 is
6. Reagents
neutral at 24°C. Lower numbers indicate increasing acidity;
6.1 Purity of Reagents—Reagent grade chemicals shall be
higher numbers, increasing alkalinity.
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit-
3. Significance and Use
tee onAnalytical Reagents of theAmerican Chemical Society,
3.1 This test method is designed to measure the pH of a 3
where such specifications are available. Other grades may be
distilled-water extract of leather. This is considered to be a
used, provided it is first ascertained that the reagent is of
measure of the acidity or alkalinity of the leather. Excessive
sufficiently high purity to permit its use without lessening the
acidity or alkalinity may have a deleterious effect on the aging
accuracy of the determination.
characteristics of leather.
6.2 Purity of Water—Unless otherwise indicated, references
3.2 This test method is suitable for development, control,
to water shall be understood to mean distilled water or water of
and service evaluation of leather.
equal purity. Distilled water shall have a pH value of not less
than 5.5 nor more than 7.0 and shall give a residue of not more
4. Interferences
than 0.5 mg, when 100 mL is evaporated and dried in a
4.1 If the leather contains an excessive amount of fats or
platinum dish.
greases or has been treated with a material to obtain water
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6.3 Standard pH Solutions:
repellency, the wettability and consequently the extractability
6.3.1 Alkaline Phosphate Buffer Solution (0.01 M trisodium
may be affected.
phosphate, pH = 11.72 at 25°C)—Dissolve 1.42 g of anhy-
4.2 If the specimen is difficult or impossible to wet, it may
drous disodium hydrogen phosphate (Na HPO ) in 100 mL of
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be treated by any of the following procedures:
4.2.1 A vacuum may be used to effect wetting.
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A Waring Blender has been found satisfactory.
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Reagent Chemicals, American Chemical Society Specifications , American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
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This test method is under the jurisdiction ofASTM Committee D31 on Leather listed by the American Chemical Society, see Analar Standards for Laboratory
and is the direct responsibility of Subcommittee D31.06 on ChemicalAnalysis.This Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
test method was developed in cooperation with the American Leather Chemists and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Assn. (Standard Method B20 – 1969). MD.
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Current edition approved April 1, 2007. Published May 2007. Originally Buffer salts and solutions prepared in accordance with National Bureau of
approved in 1969. Last previous edition approved in 2001 as D2810 – 01. DOI: Standardsrecommendationsaresoldbyreputablelaboratorysupplyhousesandmay
10.1520/D2810-07. be used.
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D2810 − 07
a 0.1 N carbonate-free solution of sodium hydroxide (NaOH) 8.3 Check for electrode
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