ASTM D4901-99(2009)
(Practice)Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
Standard Practice for Preparation of Solution of Liquid Vegetable Tannin Extracts
SIGNIFICANCE AND USE
The concentration of tannin in extracts must be reduced to analytical strength (4 g tannin per L) for analyses.
Vegetable tannin extracts are heterogeneous mixtures of components with varying solubility.
The solubility of such extracts is influenced by temperature and concentration, which affect the degree of dispersion and size of the component particles.
While the solubility is better in hot water than in cold water, it is appropriate to dissolve and disperse an extract in hot water and then let the solution cool slowly to standard room temperature.
SCOPE
1.1 This practice covers the preparation of a solution of liquid extract that is to be used in the tannin analysis of that extract.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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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Designation: D4901 − 99 (Reapproved2009)
Standard Practice for
Preparation of Solution of Liquid Vegetable Tannin Extracts
This standard is issued under the fixed designation D4901; 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.
1. Scope 4.2 Vegetable tannin extracts are heterogeneous mixtures of
components with varying solubility.
1.1 This practice covers the preparation of a solution of
liquid extract that is to be used in the tannin analysis of that 4.3 The solubility of such extracts is influenced by tempera-
extract. ture and concentration, which affect the degree of dispersion
and size of the component particles.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this 4.4 While the solubility is better in hot water than in cold
standard. water,itisappropriatetodissolveanddisperseanextractinhot
water and then let the solution cool slowly to standard room
1.3 This standard does not purport to address all of the
temperature.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Apparatus and Reagents
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 5.1 Formaldehyde—40 % solution.
5.2 Toluene—assay ≥ 99.5 %.
2. Referenced Documents
5.3 Flask,1Lvolumetric.TheClassAtype,withupperbulb
2.1 ASTM Standards:
in neck, is especially suitable for this work.
D4904 Practice for Cooling of Analytical Solutions
D6404 Practice for Sampling Vegetable Materials Contain-
6. Test Specimen
ing Tannin
6.1 The specimen shall consist of an aliquot of the sample,
2.2 ALCA Methods:
prepared as described in Practice D6404, sufficient to give a
A10 Preparation of Solution of Liquid Extracts
solution containing as nearly as possible,4gof tannin per L
(not less than 3.75 g, nor more than 4.25 g, per L).
3. Summary of Practice
3.1 The practice describes a technique found useful in the 7. Procedure
preparation of analytical strength solutions from samples of
7.1 Prepare samples of liquid extracts, as described in
liquid vegetable tannin extracts.
Practice D6404, and allow to come to room temperature.
Thoroughly mix at room temperature and transfer specimen to
4. Significance and Use
a tared container and stoppered to prevent loss of moisture.
4.1 The concentration of tannin in extracts must be reduced
Return no material which has been removed from the sample
to analytical strength (4 g tannin per L) for analyses.
for any other purpose (for example, for determination of
specific gravity, etc.) to the sample. Care must be taken that
dried material around the neck of the stopper of the sample
This practice is under the jurisdiction ofASTM Committee D31 on Leather and bottle does not contaminate the sample or specimen.Weigh the
is the direct responsibility of Subcommittee D31.01 on Vegetable Leather. This
container and specimen to the nearest 0.1 mg.
practice has been adapted from and is a replacement for MethodA10 of the Official
Methods of the American Leather Chemists Association.
NOTE 1—Shaking by hand is rarely sufficient;
...
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