ASTM D7637-10
(Test Method)Standard Test Method for Determination of Glycerin Assay by Titration (Sodium Meta Periodate)
Standard Test Method for Determination of Glycerin Assay by Titration (Sodium Meta Periodate)
SIGNIFICANCE AND USE
This test method is based on the cold oxidation of the glycerol by sodium metaperiodate in a strong acidic medium. Formaldehyde and formic acid are produced in this reaction and the latter is used to measure the glycerol content by titration with standard sodium hydroxide solution, to a pH 8.1 ± 0.1. The glycerol content is expressed as a percentage
Interferences—The glycerin sample should be free of organic compounds with more than two hydroxyl groups on adjacent carbon atoms (for example, sugars, glycols). These types of compounds may produce formic acid which interferes with the determination of the glycerol content.
SCOPE
1.1 This test method provides the quantitative determination of glycerin by the titrimetric method. It is applicable to all glycerin or glycerin/water mixtures >75 %.
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 may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of whoever uses this standard to consult the established and appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautions are listed in Section 8.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7637 − 10
StandardTest Method for
Determination of Glycerin Assay by Titration (Sodium Meta
1
Periodate)
This standard is issued under the fixed designation D7637; 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.
5
1. Scope Determination of Glycerol Content
1.1 Thistestmethodprovidesthequantitativedetermination
3. Terminology
of glycerin by the titrimetric method. It is applicable to all
3.1 Definitions:
glycerin or glycerin/water mixtures >75 %.
3.1.1 glycerin—propane-1,2,3-triol, C H (OH) (also
3 5 3
1.2 The values stated in SI units are to be regarded as
known as glycerine), 1,2,3-propanetriol, 1,2,3-
standard. No other units of measurement are included in this
trihydroxypropane, glyceritol, glycyl alcohol, glycerol. CAS
standard.
#56-81-5.
1.3 This standard may involve hazardous materials, opera-
3.1.2 SMP—Sodium Meta Periodate.
tions and equipment. This standard does not purport to address
3.1.3 For other definitions of terms used in this
all of the safety problems associated with its use. It is the
specification, refer to Terminology D4725.
responsibility of whoever uses this standard to consult the
established and appropriate safety and health practices and
4. Significance and Use
determine the applicability of regulatory limitations prior to
use. Specific precautions are listed in Section 8. 4.1 This test method is based on the cold oxidation of the
glycerol by sodium metaperiodate in a strong acidic medium.
2. Referenced Documents
Formaldehyde and formic acid are produced in this reaction
2
and the latter is used to measure the glycerol content by
2.1 ASTM Standards:
titration with standard sodium hydroxide solution, to a pH 8.1
D1193 Specification for Reagent Water
6 0.1. The glycerol content is expressed as a percentage
D4725 Terminology for Engine Coolants
(m/m).
E177 Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
CH OH 2 CHOH 2 CH OH12 NaIO→ (1)
2 2 4
E691 Practice for Conducting an Interlaboratory Study to
HCOOH12 HCHO12 NaIO 1H O
Determine the Precision of a Test Method 3 2
4.2 Interferences—The glycerin sample should be free of
2.2 Other Standards:
organic compounds with more than two hydroxyl groups on
The United States Pharmacopoeia 31 Glycerin Monograph –
3
adjacent carbon atoms (for example, sugars, glycols). These
Assay Method
types of compounds may produce formic acid which interferes
AOCS Official Method EA6-94 (ReplacesAOCS EA6-51),
4
with the determination of the glycerol content.
Determination of Crude Glycerin, Titrimetric Method
BS 5711: Part 3, 1979 Sampling and Test for Glycerol -
5. Apparatus
5.1 Burette—50 mL“TypeA” unit that can deliver 30 drops
1
This test method is under the jurisdiction ofASTM Committee D15 on Engine
per mL and calibrated to meet the NIST standards.
Coolants and Related Fluids and is the direct responsibility of Subcommittee
NOTE 1— It is critical that all glassware be “Type A” and thoroughly
D15.93 on Research and Long Range Planning.
cleaned before use as dirty glassware will impact the analysis results.
Current edition approved June 1, 2010. Published July 2010. DOI: 10.1520/
D7637–10.
5.2 pH meter, fitted with glass electrode.
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
NOTE 2—The pH meter should be standardized with a minimum of two
Standards volume information, refer to the standard’s Document Summary page on
buffer solutions at 10.0 and 7.0. (See 7.12.)
the ASTM website.
3
Available from U.S. Pharmacopeia (USP), 12601 Twinbrook Pkwy., Rockville,
MD 20852-1790, http://www.usp.org.
4 5
Available from AOCS, 2710 S. Boulder, Urbana, IL 61802-6996, http:// Available from British Standards Institute (BSI), 389 Chiswick High Rd.,
www.aocs.org. London W4 4AL, U.K., http://www.bsi-global.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7637 − 10
5.3 Stirrer—preference should be given to a magnetic stir- 7.11 Bromothymol blue indicator solution—Dissolve 100
rer. In this case, check that it does not influence the pH meter. mg of bromothymol blue in 100 mL of water to make 100 mL
of indicator solution.
6. Purity of Reagents and Water
7.12 pH Buffers (7.0 6 0.01 and 10.0 6 0.01 at 25°C)
6.1 Purity of Reagents—Reagent grade chemicals shall be
needed for pH meter standardization.
used in all tests. Unless otherwise indicated, it is intended that
7.13 Freshly boiled water, or equivalent. (See 6
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