ASTM D7736-12

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Designation: D7736 − 12
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
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Glycol
This standard is issued under the fixed designation D7736; 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. Summary of Test Method
1.1 This test method covers the determination of free acids 4.1 This test method is used to determine the acid and ester
and glycol esters in ethylene glycol by titration. content of ethylene glycol by titration.The sample is titrated to
the phenolphthalein end point with 0.02 N NaOH to determine
1.2 This test method is for used on ethylene glycol used for
the acidity. Then a known amount of base is added and the
the manufacture of engine coolant. It can not be used on
sample is heated at 100°C to hydrolyze the esters. It is then
formulated engine coolant. The inhibitors will interfere with
back-titrated with 0.02 N sulfuric acid to determine the ester
the determination.
content.
1.3 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
5. Significance and Use
standard.
5.1 The presence of acids or glycol esters in the ethylene
1.4 This standard does not purport to address all of the
glycol used to produce engine coolant is undesirable. Under
safety concerns, if any, associated with its use. It is the
conditions in an engine cooling system, the esters can hydro-
responsibility of the user of this standard to establish appro-
lyze to form glycol and an acid. The acid will react with the
priate safety and health practices and determine the applica-
corrosion inhibitors, thereby reducing the useful life of the
bility of regulatory limitations prior to use.
coolant. This method can determine the amount of acid and
glycol ester present in the ethylene glycol.
2. Referenced Documents
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6. Interferences
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solu-
6.1 This test method is based on a color change titration.
tions of Engine Coolants orAntirusts forTesting Purposes
Glycol with a strong color could interfere with the results of
D1193 Specification for Reagent Water
this method.
D4725 Terminology for Engine Coolants and Related Fluids
6.2 High pH recycled glycols streams will affect the results
E177 Practice for Use of the Terms Precision and Bias in
of this test method.
ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to
7. Apparatus
Determine the Precision of a Test Method
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
3. Terminology
8. Reagents and Materials
3.1 Definitions:
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenol-
3.1.1 For definitions of terms used in this test method, refer
phthalein in methanol or ethanol and dilute to 100 mL.
to Terminology D4725.
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
8.3 Sulfuric Acid (H SO ), 0.02 N in water.
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This test method is under the jurisdiction ofASTM Committee D15 on Engine
8.4 Purity of Water—Unless otherwise indicated, references
Coolants and Related Fluids and is the direct responsibility of Subcommittee
D15.04 on Chemical Properties.
to water shall be understood to mean reagent water as defined
Current edition approved April 1, 2012. Published June 2012. Originally
by Type II or III of Specification D1193.
approved in 2011. Last previous edition approved in 2011 as D7736 - 11. DOI:
10.1520/D7736–12.
8.5 Purity of Reagents—Reagent grade chemicals shall be
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
used in all tests. Unless otherwise indicated, it is intended that
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
all reagents shall conform to the specifications of the Commit-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. tee onAnalytical Reagents of theAmerican Chemical Society,
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D7736 − 12
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where such specifications are available. Other grades may be 11. Calculation
used, provided it is first ascertained that the reagent is of
11.1 Acidity:
sufficiently high purity to permit its use without lessening the
% acetic acid5
accuracy of the determination.
~mL NaOH!~N NaOH!
~60.0 g/equivalent!~1 L/1000 mL!
9. Sampling
3100
g of sample
9.1 Sample the material in accordance with Practice D1176.
where:
10. Procedure
N = normality of the NaOH used.
10.1 Acid Content:
11.2 Ester Content:
10.1.1 Adjustment of pH—Pipet 25.0
...