ASTM D7736-12(2018)
(Test Method)Standard Test Method for Determination of Acids and Glycol Esters in Ethylene Glycol
Standard Test Method for Determination of Acids and Glycol Esters in Ethylene Glycol
SIGNIFICANCE AND USE
5.1 The presence of acids or glycol esters in the ethylene glycol used to produce engine coolant is undesirable. Under conditions in an engine cooling system, the esters can hydrolyze to form glycol and an acid. The acid will react with the corrosion inhibitors, thereby reducing the useful life of the coolant. This method can determine the amount of acid and glycol ester present in the ethylene glycol.
SCOPE
1.1 This test method covers the determination of free acids and glycol esters in ethylene glycol by titration.
1.2 This test method is for used on ethylene glycol used for the manufacture of engine coolant. It can not be used on formulated engine coolant. The inhibitors will interfere with the determination.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D7736 − 12 (Reapproved 2018)
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
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 Determine the Precision of a Test Method
1.1 This test method covers the determination of free acids
3. Terminology
and glycol esters in ethylene glycol by titration.
3.1 Definitions:
1.2 This test method is for used on ethylene glycol used for
3.1.1 For definitions of terms used in this test method, refer
the manufacture of engine coolant. It can not be used on
to Terminology D4725.
formulated engine coolant. The inhibitors will interfere with
the determination.
4. Summary of Test Method
1.3 The values stated in SI units are to be regarded as
4.1 This test method is used to determine the acid and ester
standard. No other units of measurement are included in this
content of ethylene glycol by titration.The sample is titrated to
standard.
the phenolphthalein end point with 0.02 N NaOH to determine
1.4 This standard does not purport to address all of the
the acidity. Then a known amount of base is added and the
safety concerns, if any, associated with its use. It is the
sample is heated at 100 °C to hydrolyze the esters. It is then
responsibility of the user of this standard to establish appro-
back-titrated with 0.02 N sulfuric acid to determine the ester
priate safety, health, and environmental practices and deter-
content.
mine the applicability of regulatory limitations prior to use.
5. Significance and Use
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5.1 The presence of acids or glycol esters in the ethylene
ization established in the Decision on Principles for the
glycol used to produce engine coolant is undesirable. Under
Development of International Standards, Guides and Recom-
conditions in an engine cooling system, the esters can hydro-
mendations issued by the World Trade Organization Technical
lyze to form glycol and an acid. The acid will react with the
Barriers to Trade (TBT) Committee.
corrosion inhibitors, thereby reducing the useful life of the
coolant. This method can determine the amount of acid and
2. Referenced Documents
glycol ester present in the ethylene glycol.
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solu- 6. Interferences
tions of Engine Coolants orAntirusts forTesting Purposes
6.1 This test method is based on a color change titration.
D1193 Specification for Reagent Water
Glycol with a strong color could interfere with the results of
D4725 Terminology for Engine Coolants and Related Fluids
this method.
E177 Practice for Use of the Terms Precision and Bias in
6.2 High pH recycled glycols streams will affect the results
ASTM Test Methods
of this test method.
E691 Practice for Conducting an Interlaboratory Study to
7. Apparatus
This test method is under the jurisdiction ofASTM Committee D15 on Engine
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
Coolants and Related Fluids and is the direct responsibility of Subcommittee
D15.04 on Chemical Properties.
8. Reagents and Materials
Current edition approved March 1, 2018. Published March 2018. Originally
approved in 2011. Last previous edition approved in 2012 as D7736 - 12. DOI:
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenol-
10.1520/D7736-12R18.
phthalein in methanol or ethanol and dilute to 100 mL.
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
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 8.3 Sulfuric Acid (H SO ), 0.02 N in water.
2 4
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7736 − 12 (2018)
TABLE 1 Recommended Sample Sizes
10.2.2 Determination of the Ester Content—Remove bottles
Estimated Ester from the bath and cool to room temperature. When cool, add 3
Sample Size, g Sample Method
Content, wt %
drops of phenolphthalein solution to each and titrate with 0.02
< 0.10 25.0 Weigh the sample to the
NH SO until disappearance of pink color.
0.10 to 0.20 10.0 nearest 0.1 g into the 2 4
A
0.20 to 0.50 5.0 bottle
of water prepared in 11. Calculation
10.1.1
11.1 Acidity:
A
Report as “>0.50 wt %” if the titration determination exceeds 0.50 %.
% acetic acid5
mL NaOH N NaOH
~ !~ !
60.0 g/equivalent 1 L/1000 mL
~ !~ !
8.4 Purity of Water—Unless otherwise indicated, references
g of sample
to water shall be understood to mean reagent water as defined
by Type II or III of Specification D1193.
where:
N = normality of the NaOH used.
8.5 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
11.2 Ester Content:
all reagents shall conform to the specifications of the Commit-
% esters as acetic acid 5
~ !
tee onAnalytical Reagents of theAmerican Chemical Society,
3 ~B 2 A!~NH SO !
2 4
where such specifications are available. Other grades may be
60.0g/equivalent 1 L/1000 mL
~ !~ !
used, provided it is first ascertained that the reagent is of
g of sample
sufficiently high purity to permit its use without lessening the
esters, ppm as acetic acid 5 % esters as acetic acid 310 000
accuracy of the determination. ~ ! ~ !
where:
9. Sampling
N = normality of the H SO used,
2 4
9.1 Sample the material in accordance with Practice D1176.
B =H SO used to titrate the blank, mL, and
2 4
A =H SO used to titrate the sample, mL.
2 4
10. Procedure
12. Report
10.1 Acid Content:
10.1.1 Adjustment of pH—Pipet 25.00 mL of deionized
12.1 Report the average of the three determinations of
water into each of three 250 mL bottles. Add 3 drops of
acidity as mass percent acetic acid.
phenolphthalein solution to each. Titrate with 0.02 N sodium
12.2 Report the average of the three determinations of the
hydroxidetothefirstpinkendpointpermanentforatleast15 s.
ester content as ppm acetic acid.
Do not record this volume of titrant. Repeat for each bottle.
10.1.2 Determination of Sample Acidit
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7736 − 12 D7736 − 12 (Reapproved 2018)
Standard Test Method for
Determination of Acids and Glycol Esters in Ethylene
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
1.1 This test method covers the determination of free acids and glycol esters in ethylene glycol by titration.
1.2 This test method is for used on ethylene glycol used for the manufacture of engine coolant. It can not be used on formulated
engine coolant. The inhibitors will interfere with the determination.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1176 Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
D1193 Specification for Reagent Water
D4725 Terminology for Engine Coolants and Related Fluids
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4725.
4. Summary of Test Method
4.1 This test method is used to determine the acid and ester content of ethylene glycol by titration. The sample is titrated to the
phenolphthalein end point with 0.02 N NaOH to determine the acidity. Then a known amount of base is added and the sample is
heated at 100°C100 °C to hydrolyze the esters. It is then back-titrated with 0.02 N sulfuric acid to determine the ester content.
5. Significance and Use
5.1 The presence of acids or glycol esters in the ethylene glycol used to produce engine coolant is undesirable. Under conditions
in an engine cooling system, the esters can hydrolyze to form glycol and an acid. The acid will react with the corrosion inhibitors,
thereby reducing the useful life of the coolant. This method can determine the amount of acid and glycol ester present in the
ethylene glycol.
This test method is under the jurisdiction of ASTM Committee D15 on Engine Coolants and Related Fluids and is the direct responsibility of Subcommittee D15.04 on
Chemical Properties.
Current edition approved April 1, 2012March 1, 2018. Published June 2012March 2018. Originally approved in 2011. Last previous edition approved in 20112012 as
D7736 - 11.D7736 - 12. DOI: 10.1520/D7736–12.10.1520/D7736-12R18.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7736 − 12 (2018)
6. Interferences
6.1 This test method is based on a color change titration. Glycol with a strong color could interfere with the results of this
method.
6.2 High pH recycled glycols streams will affect the results of this test method.
7. Apparatus
7.1 250 mL Borosilicate Glass Bottles, with screw caps.
8. Reagents and Materials
8.1 Phenolphthalein Solution—Dissolve 0.5 g of phenolphthalein in methanol or ethanol and dilute to 100 mL.
8.2 Sodium Hydroxide (NaOH), 0.02 N in water.
8.3 Sulfuric Acid (H SO ), 0.02 N in water.
2 4
8.4 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by
Type II or III of Specification D1193.
8.5 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
9. Sampling
9.1 Sample the material in accordance with Practice D1176.
10. Procedure
10.1 Acid Content:
10.1.1 Adjustment of pH—Pipet 25.00 mL of deionized water into each of three 250 mL bottles. Add 3 drops of phenolphthalein
solution to each. Titrate with 0.02 N sodium hydroxide to the first pink end point permanent for at least 15 seconds. 15 s. Do not
record this volume of titrant. Repeat for each bottle.
10.1.2 Determination of Sample Acidity:
10.1.2.1 Add an amount of sample as indicated in Table 1 to the nearest 0.1 g into the bottle of deionized water prepared in
10.1.1.
10.1.2.2 Titrate each sample with 0.02 N sodium hydroxide to the first pink end point permanent for at least 15 s. This volume
of titrant is used to calculate the percent acid.
NOTE 1—If the ester content is completely unknown, a trial titration beginning with 25 g of sample may be conducted to develop a preliminary estimate
before the actual test titration is performed. If the trial suggests concentration of over 0.10 wt % (1000 ppm) then reduce the sample to 10 g and repeat.
The second trial should provide enough information to direct an appropriate choice of the sample quantity to be used.
10.2 Total Ester Content:
10.2.1 Hydrolysis of the Esters—Pipet 25.00 mL of 0.02 N sodium hydroxide into each bottle used in 10.1.2. Prepare a blank
for each sample by pipetting 25.00 mL of 0.02 N sodium hydroxide into three clean, 250 mL bottles. Immerse the pairs of bottles
in a boiling water bath for 1 h. (Tap water is suitable.) The weight of the bottl
...
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